diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 5a937ad0..cdafba1a 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -1,5 +1,19 @@
 # Release History
 
+## 2.4.0 (2019-12-11)
+
+**Added**
+
+- feat: validate with python script, ref #773
+
+**Changed**
+
+- refactor: make loader as submodule, split to check/locate/load/buildup
+- refactor: make built_in as submodule, split to comparators and functions
+- refactor: adjust code for context and validator
+- docs: update cli argument help
+- adjust format code, remove unused import
+
 ## 2.3.3 (2019-12-04)
 
 **Fixed**
diff --git a/httprunner/__init__.py b/httprunner/__init__.py
index 4d5c880e..cb8ce2a1 100644
--- a/httprunner/__init__.py
+++ b/httprunner/__init__.py
@@ -1,4 +1,4 @@
-__version__ = "2.3.3"
+__version__ = "2.4.0"
 __description__ = "One-stop solution for HTTP(S) testing."
 
 __all__ = ["__version__", "__description__"]
diff --git a/httprunner/api.py b/httprunner/api.py
index 6d6a3b99..18ec9389 100644
--- a/httprunner/api.py
+++ b/httprunner/api.py
@@ -2,7 +2,7 @@ import os
 import unittest
 
 from httprunner import (__version__, exceptions, loader, logger, parser,
-                        report, runner, utils, validator)
+                        report, runner, utils)
 
 
 class HttpRunner(object):
@@ -260,7 +260,7 @@ class HttpRunner(object):
         """
         # load tests
         self.exception_stage = "load tests"
-        tests_mapping = loader.load_tests(path, dot_env_path)
+        tests_mapping = loader.load_cases(path, dot_env_path)
 
         if mapping:
             tests_mapping["project_mapping"]["variables"] = mapping
@@ -280,9 +280,9 @@ class HttpRunner(object):
 
         """
         logger.log_info("HttpRunner version: {}".format(__version__))
-        if validator.is_testcase_path(path_or_tests):
+        if loader.is_testcase_path(path_or_tests):
             return self.run_path(path_or_tests, dot_env_path, mapping)
-        elif validator.is_testcases(path_or_tests):
+        elif loader.is_testcases(path_or_tests):
             return self.run_tests(path_or_tests)
         else:
             raise exceptions.ParamsError("Invalid testcase path or testcases: {}".format(path_or_tests))
diff --git a/httprunner/built_in.py b/httprunner/built_in.py
deleted file mode 100644
index 43524d3f..00000000
--- a/httprunner/built_in.py
+++ /dev/null
@@ -1,206 +0,0 @@
-# encoding: utf-8
-
-"""
-Built-in dependent functions used in YAML/JSON testcases.
-"""
-
-import datetime
-import os
-import random
-import re
-import string
-import time
-
-import filetype
-from requests_toolbelt import MultipartEncoder
-
-from httprunner.compat import basestring, builtin_str, integer_types
-from httprunner.exceptions import ParamsError
-
-PWD = os.getcwd()
-
-
-###############################################################################
-##  built-in functions
-###############################################################################
-
-def gen_random_string(str_len):
-    """ generate random string with specified length
-    """
-    return ''.join(
-        random.choice(string.ascii_letters + string.digits) for _ in range(str_len))
-
-
-def get_timestamp(str_len=13):
-    """ get timestamp string, length can only between 0 and 16
-    """
-    if isinstance(str_len, integer_types) and 0 < str_len < 17:
-        return builtin_str(time.time()).replace(".", "")[:str_len]
-
-    raise ParamsError("timestamp length can only between 0 and 16.")
-
-
-def get_current_date(fmt="%Y-%m-%d"):
-    """ get current date, default format is %Y-%m-%d
-    """
-    return datetime.datetime.now().strftime(fmt)
-
-
-def sleep(n_secs):
-    """ sleep n seconds
-    """
-    time.sleep(n_secs)
-
-
-###############################################################################
-##  upload files with requests-toolbelt
-#   e.g.
-#   - test:
-#      name: upload file
-#      variables:
-#          file_path: "data/test.env"
-#          multipart_encoder: ${multipart_encoder(file=$file_path)}
-#      request:
-#          url: /post
-#          method: POST
-#          headers:
-#              Content-Type: ${multipart_content_type($multipart_encoder)}
-#          data: $multipart_encoder
-#      validate:
-#          - eq: ["status_code", 200]
-#          - startswith: ["content.files.file", "UserName=test"]
-###############################################################################
-
-def multipart_encoder(**kwargs):
-    """ initialize MultipartEncoder with uploading fields.
-    """
-
-    def get_filetype(file_path):
-        file_type = filetype.guess(file_path)
-        if file_type:
-            return file_type.mime
-        else:
-            return "text/html"
-
-    fields_dict = {}
-    for key, value in kwargs.items():
-
-        if os.path.isabs(value):
-            _file_path = value
-            is_file = True
-        else:
-            global PWD
-            _file_path = os.path.join(PWD, value)
-            is_file = os.path.isfile(_file_path)
-
-        if is_file:
-            filename = os.path.basename(_file_path)
-            with open(_file_path, 'rb') as f:
-                mime_type = get_filetype(_file_path)
-                fields_dict[key] = (filename, f.read(), mime_type)
-        else:
-            fields_dict[key] = value
-
-    return MultipartEncoder(fields=fields_dict)
-
-
-def multipart_content_type(multipart_encoder):
-    """ prepare Content-Type for request headers
-    """
-    return multipart_encoder.content_type
-
-
-###############################################################################
-##  built-in comparators
-###############################################################################
-
-def equals(check_value, expect_value):
-    assert check_value == expect_value
-
-
-def less_than(check_value, expect_value):
-    assert check_value < expect_value
-
-
-def less_than_or_equals(check_value, expect_value):
-    assert check_value <= expect_value
-
-
-def greater_than(check_value, expect_value):
-    assert check_value > expect_value
-
-
-def greater_than_or_equals(check_value, expect_value):
-    assert check_value >= expect_value
-
-
-def not_equals(check_value, expect_value):
-    assert check_value != expect_value
-
-
-def string_equals(check_value, expect_value):
-    assert builtin_str(check_value) == builtin_str(expect_value)
-
-
-def length_equals(check_value, expect_value):
-    assert isinstance(expect_value, integer_types)
-    assert len(check_value) == expect_value
-
-
-def length_greater_than(check_value, expect_value):
-    assert isinstance(expect_value, integer_types)
-    assert len(check_value) > expect_value
-
-
-def length_greater_than_or_equals(check_value, expect_value):
-    assert isinstance(expect_value, integer_types)
-    assert len(check_value) >= expect_value
-
-
-def length_less_than(check_value, expect_value):
-    assert isinstance(expect_value, integer_types)
-    assert len(check_value) < expect_value
-
-
-def length_less_than_or_equals(check_value, expect_value):
-    assert isinstance(expect_value, integer_types)
-    assert len(check_value) <= expect_value
-
-
-def contains(check_value, expect_value):
-    assert isinstance(check_value, (list, tuple, dict, basestring))
-    assert expect_value in check_value
-
-
-def contained_by(check_value, expect_value):
-    assert isinstance(expect_value, (list, tuple, dict, basestring))
-    assert check_value in expect_value
-
-
-def type_match(check_value, expect_value):
-    def get_type(name):
-        if isinstance(name, type):
-            return name
-        elif isinstance(name, basestring):
-            try:
-                return __builtins__[name]
-            except KeyError:
-                raise ValueError(name)
-        else:
-            raise ValueError(name)
-
-    assert isinstance(check_value, get_type(expect_value))
-
-
-def regex_match(check_value, expect_value):
-    assert isinstance(expect_value, basestring)
-    assert isinstance(check_value, basestring)
-    assert re.match(expect_value, check_value)
-
-
-def startswith(check_value, expect_value):
-    assert builtin_str(check_value).startswith(builtin_str(expect_value))
-
-
-def endswith(check_value, expect_value):
-    assert builtin_str(check_value).endswith(builtin_str(expect_value))
diff --git a/httprunner/builtin/__init__.py b/httprunner/builtin/__init__.py
new file mode 100644
index 00000000..0c7cf6db
--- /dev/null
+++ b/httprunner/builtin/__init__.py
@@ -0,0 +1,2 @@
+from httprunner.builtin.comparators import *
+from httprunner.builtin.functions import *
diff --git a/httprunner/builtin/comparators.py b/httprunner/builtin/comparators.py
new file mode 100644
index 00000000..3a522993
--- /dev/null
+++ b/httprunner/builtin/comparators.py
@@ -0,0 +1,99 @@
+"""
+Built-in validate comparators.
+"""
+
+import re
+
+from httprunner.compat import basestring, builtin_str, integer_types
+
+
+def equals(check_value, expect_value):
+    assert check_value == expect_value
+
+
+def less_than(check_value, expect_value):
+    assert check_value < expect_value
+
+
+def less_than_or_equals(check_value, expect_value):
+    assert check_value <= expect_value
+
+
+def greater_than(check_value, expect_value):
+    assert check_value > expect_value
+
+
+def greater_than_or_equals(check_value, expect_value):
+    assert check_value >= expect_value
+
+
+def not_equals(check_value, expect_value):
+    assert check_value != expect_value
+
+
+def string_equals(check_value, expect_value):
+    assert builtin_str(check_value) == builtin_str(expect_value)
+
+
+def length_equals(check_value, expect_value):
+    assert isinstance(expect_value, integer_types)
+    assert len(check_value) == expect_value
+
+
+def length_greater_than(check_value, expect_value):
+    assert isinstance(expect_value, integer_types)
+    assert len(check_value) > expect_value
+
+
+def length_greater_than_or_equals(check_value, expect_value):
+    assert isinstance(expect_value, integer_types)
+    assert len(check_value) >= expect_value
+
+
+def length_less_than(check_value, expect_value):
+    assert isinstance(expect_value, integer_types)
+    assert len(check_value) < expect_value
+
+
+def length_less_than_or_equals(check_value, expect_value):
+    assert isinstance(expect_value, integer_types)
+    assert len(check_value) <= expect_value
+
+
+def contains(check_value, expect_value):
+    assert isinstance(check_value, (list, tuple, dict, basestring))
+    assert expect_value in check_value
+
+
+def contained_by(check_value, expect_value):
+    assert isinstance(expect_value, (list, tuple, dict, basestring))
+    assert check_value in expect_value
+
+
+def type_match(check_value, expect_value):
+    def get_type(name):
+        if isinstance(name, type):
+            return name
+        elif isinstance(name, basestring):
+            try:
+                return __builtins__[name]
+            except KeyError:
+                raise ValueError(name)
+        else:
+            raise ValueError(name)
+
+    assert isinstance(check_value, get_type(expect_value))
+
+
+def regex_match(check_value, expect_value):
+    assert isinstance(expect_value, basestring)
+    assert isinstance(check_value, basestring)
+    assert re.match(expect_value, check_value)
+
+
+def startswith(check_value, expect_value):
+    assert builtin_str(check_value).startswith(builtin_str(expect_value))
+
+
+def endswith(check_value, expect_value):
+    assert builtin_str(check_value).endswith(builtin_str(expect_value))
diff --git a/httprunner/builtin/functions.py b/httprunner/builtin/functions.py
new file mode 100644
index 00000000..0cca0295
--- /dev/null
+++ b/httprunner/builtin/functions.py
@@ -0,0 +1,105 @@
+"""
+Built-in functions used in YAML/JSON testcases.
+"""
+
+import datetime
+import os
+import random
+import string
+import time
+
+import filetype
+from requests_toolbelt import MultipartEncoder
+
+from httprunner.compat import builtin_str, integer_types
+from httprunner.exceptions import ParamsError
+
+PWD = os.getcwd()
+
+
+def gen_random_string(str_len):
+    """ generate random string with specified length
+    """
+    return ''.join(
+        random.choice(string.ascii_letters + string.digits) for _ in range(str_len))
+
+
+def get_timestamp(str_len=13):
+    """ get timestamp string, length can only between 0 and 16
+    """
+    if isinstance(str_len, integer_types) and 0 < str_len < 17:
+        return builtin_str(time.time()).replace(".", "")[:str_len]
+
+    raise ParamsError("timestamp length can only between 0 and 16.")
+
+
+def get_current_date(fmt="%Y-%m-%d"):
+    """ get current date, default format is %Y-%m-%d
+    """
+    return datetime.datetime.now().strftime(fmt)
+
+
+def sleep(n_secs):
+    """ sleep n seconds
+    """
+    time.sleep(n_secs)
+
+
+"""
+upload files with requests-toolbelt
+e.g.
+
+    - test:
+        name: upload file
+        variables:
+            file_path: "data/test.env"
+            multipart_encoder: ${multipart_encoder(file=$file_path)}
+        request:
+            url: /post
+            method: POST
+            headers:
+                Content-Type: ${multipart_content_type($multipart_encoder)}
+            data: $multipart_encoder
+        validate:
+            - eq: ["status_code", 200]
+            - startswith: ["content.files.file", "UserName=test"]
+"""
+
+
+def multipart_encoder(**kwargs):
+    """ initialize MultipartEncoder with uploading fields.
+    """
+
+    def get_filetype(file_path):
+        file_type = filetype.guess(file_path)
+        if file_type:
+            return file_type.mime
+        else:
+            return "text/html"
+
+    fields_dict = {}
+    for key, value in kwargs.items():
+
+        if os.path.isabs(value):
+            _file_path = value
+            is_file = True
+        else:
+            global PWD
+            _file_path = os.path.join(PWD, value)
+            is_file = os.path.isfile(_file_path)
+
+        if is_file:
+            filename = os.path.basename(_file_path)
+            with open(_file_path, 'rb') as f:
+                mime_type = get_filetype(_file_path)
+                fields_dict[key] = (filename, f.read(), mime_type)
+        else:
+            fields_dict[key] = value
+
+    return MultipartEncoder(fields=fields_dict)
+
+
+def multipart_content_type(multipart_encoder):
+    """ prepare Content-Type for request headers
+    """
+    return multipart_encoder.content_type
diff --git a/httprunner/cli.py b/httprunner/cli.py
index 389fdc80..559e7012 100644
--- a/httprunner/cli.py
+++ b/httprunner/cli.py
@@ -5,11 +5,11 @@ import sys
 from httprunner import __description__, __version__
 from httprunner.api import HttpRunner
 from httprunner.compat import is_py2
+from httprunner.loader import validate_json_file
 from httprunner.logger import color_print
 from httprunner.report import gen_html_report
 from httprunner.utils import (create_scaffold, get_python2_retire_msg,
                               prettify_json_file)
-from httprunner.validator import validate_json_file
 
 
 def main():
@@ -23,8 +23,8 @@ def main():
         '-V', '--version', dest='version', action='store_true',
         help="show version")
     parser.add_argument(
-        'testcase_paths', nargs='*',
-        help="testcase file path")
+        'testfile_paths', nargs='*',
+        help="Specify api/testcase/testsuite file paths to run.")
     parser.add_argument(
         '--log-level', default='INFO',
         help="Specify logging level, default is INFO.")
@@ -36,19 +36,19 @@ def main():
         help="Specify .env file path, which is useful for keeping sensitive data.")
     parser.add_argument(
         '--report-template',
-        help="specify report template path.")
+        help="Specify report template path.")
     parser.add_argument(
         '--report-dir',
-        help="specify report save directory.")
+        help="Specify report save directory.")
     parser.add_argument(
         '--report-file',
-        help="specify report file path, this has higher priority than specifying report dir.")
+        help="Specify report file path, this has higher priority than specifying report dir.")
+    parser.add_argument(
+        '--save-tests', action='store_true', default=False,
+        help="Save loaded/parsed/summary json data to JSON files.")
     parser.add_argument(
         '--failfast', action='store_true', default=False,
         help="Stop the test run on the first error or failure.")
-    parser.add_argument(
-        '--save-tests', action='store_true', default=False,
-        help="Save loaded tests and parsed tests to JSON file.")
     parser.add_argument(
         '--startproject',
         help="Specify new project name.")
@@ -96,9 +96,9 @@ def main():
             report_dir = args.report_dir or os.path.join(runner.project_working_directory, "reports")
             gen_html_report(
                 summary,
-                args.report_template,
-                report_dir,
-                args.report_file
+                report_template=args.report_template,
+                report_dir=report_dir,
+                report_file=args.report_file
             )
             err_code |= (0 if summary and summary["success"] else 1)
     except Exception:
diff --git a/httprunner/context.py b/httprunner/context.py
index 980f44a9..c08af242 100644
--- a/httprunner/context.py
+++ b/httprunner/context.py
@@ -1,4 +1,4 @@
-from httprunner import exceptions, logger, parser, utils
+from httprunner import parser, utils
 
 
 class SessionContext(object):
@@ -13,11 +13,12 @@ class SessionContext(object):
         >>> context.update_session_variables(variables)
 
     """
+
     def __init__(self, variables=None):
         variables_mapping = utils.ensure_mapping_format(variables or {})
         self.session_variables_mapping = parser.parse_variables_mapping(variables_mapping)
+        self.test_variables_mapping = {}
         self.init_test_variables()
-        self.validation_results = []
 
     def init_test_variables(self, variables_mapping=None):
         """ init test variables, called when each test(api) starts.
@@ -61,110 +62,3 @@ class SessionContext(object):
             content may be in any data structure, include dict, list, tuple, number, string, etc.
         """
         return parser.parse_lazy_data(content, self.test_variables_mapping)
-
-    def __eval_validator_check(self, check_item, resp_obj):
-        """ evaluate check item in validator.
-
-        Args:
-            check_item: check_item should only be the following 5 formats:
-                1, variable reference, e.g. $token
-                2, function reference, e.g. ${is_status_code_200($status_code)}
-                3, dict or list, maybe containing variable/function reference, e.g. {"var": "$abc"}
-                4, string joined by delimiter. e.g. "status_code", "headers.content-type"
-                5, regex string, e.g. "LB[\d]*(.*)RB[\d]*"
-
-            resp_obj: response object
-
-        """
-        if isinstance(check_item, (dict, list)) \
-            or isinstance(check_item, parser.LazyString):
-            # format 1/2/3
-            check_value = self.eval_content(check_item)
-        else:
-            # format 4/5
-            check_value = resp_obj.extract_field(check_item)
-
-        return check_value
-
-    def __eval_validator_expect(self, expect_item):
-        """ evaluate expect item in validator.
-
-        Args:
-            expect_item: expect_item should only be in 2 types:
-                1, variable reference, e.g. $expect_status_code
-                2, actual value, e.g. 200
-
-        """
-        expect_value = self.eval_content(expect_item)
-        return expect_value
-
-    def validate(self, validators, resp_obj):
-        """ make validation with comparators
-        """
-        self.validation_results = []
-        if not validators:
-            return
-
-        logger.log_debug("start to validate.")
-
-        validate_pass = True
-        failures = []
-
-        for validator in validators:
-            # validator should be LazyFunction object
-            if not isinstance(validator, parser.LazyFunction):
-                raise exceptions.ValidationFailure(
-                    "validator should be parsed first: {}".format(validators))
-
-            # evaluate validator args with context variable mapping.
-            validator_args = validator.get_args()
-            check_item, expect_item = validator_args
-            check_value = self.__eval_validator_check(
-                check_item,
-                resp_obj
-            )
-            expect_value = self.__eval_validator_expect(expect_item)
-            validator.update_args([check_value, expect_value])
-
-            comparator = validator.func_name
-            validator_dict = {
-                "comparator": comparator,
-                "check": check_item,
-                "check_value": check_value,
-                "expect": expect_item,
-                "expect_value": expect_value
-            }
-            validate_msg = "\nvalidate: {} {} {}({})".format(
-                check_item,
-                comparator,
-                expect_value,
-                type(expect_value).__name__
-            )
-
-            try:
-                validator.to_value(self.test_variables_mapping)
-                validator_dict["check_result"] = "pass"
-                validate_msg += "\t==> pass"
-                logger.log_debug(validate_msg)
-            except (AssertionError, TypeError):
-                validate_pass = False
-                validator_dict["check_result"] = "fail"
-                validate_msg += "\t==> fail"
-                validate_msg += "\n{}({}) {} {}({})".format(
-                    check_value,
-                    type(check_value).__name__,
-                    comparator,
-                    expect_value,
-                    type(expect_value).__name__
-                )
-                logger.log_error(validate_msg)
-                failures.append(validate_msg)
-
-            self.validation_results.append(validator_dict)
-
-            # restore validator args, in case of running multiple times
-            validator.update_args(validator_args)
-
-        if not validate_pass:
-            failures_string = "\n".join([failure for failure in failures])
-            raise exceptions.ValidationFailure(failures_string)
diff --git a/httprunner/loader/__init__.py b/httprunner/loader/__init__.py
new file mode 100644
index 00000000..99bbdf3c
--- /dev/null
+++ b/httprunner/loader/__init__.py
@@ -0,0 +1,23 @@
+"""
+HttpRunner loader
+
+- check: validate testcase data structure with JSON schema (TODO)
+- locate: locate debugtalk.py, make it's dir as project root path
+- load: load testcase files and relevant data, including debugtalk.py, .env, yaml/json api/testcases, csv, etc.
+- buildup: assemble loaded content to httprunner testcase/testsuite data structure
+
+"""
+
+from httprunner.loader.check import is_testcase_path, is_testcases, validate_json_file
+from httprunner.loader.load import load_csv_file, load_builtin_functions
+from httprunner.loader.buildup import load_cases, load_project_data
+
+__all__ = [
+    "is_testcase_path",
+    "is_testcases",
+    "validate_json_file",
+    "load_csv_file",
+    "load_builtin_functions",
+    "load_project_data",
+    "load_cases"
+]
diff --git a/httprunner/loader.py b/httprunner/loader/buildup.py
similarity index 61%
rename from httprunner/loader.py
rename to httprunner/loader/buildup.py
index 191011e5..b2e9a16d 100644
--- a/httprunner/loader.py
+++ b/httprunner/loader/buildup.py
@@ -1,277 +1,16 @@
-import csv
 import importlib
-import io
-import json
 import os
-import sys
 
-import yaml
+from httprunner import exceptions, logger, utils
+from httprunner.builtin import functions
+from httprunner.loader.load import load_module_functions, load_folder_content, load_file, load_dot_env_file, \
+    load_folder_files
+from httprunner.loader.locate import init_project_working_directory, get_project_working_directory
 
-from httprunner import built_in, exceptions, logger, utils, validator
-
-try:
-    # PyYAML version >= 5.1
-    # ref: https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load(input)-Deprecation
-    yaml.warnings({'YAMLLoadWarning': False})
-except AttributeError:
-    pass
-
-
-###############################################################################
-#   file loader
-###############################################################################
-
-
-def _check_format(file_path, content):
-    """ check testcase format if valid
-    """
-    # TODO: replace with JSON schema validation
-    if not content:
-        # testcase file content is empty
-        err_msg = u"Testcase file content is empty: {}".format(file_path)
-        logger.log_error(err_msg)
-        raise exceptions.FileFormatError(err_msg)
-
-    elif not isinstance(content, (list, dict)):
-        # testcase file content does not match testcase format
-        err_msg = u"Testcase file content format invalid: {}".format(file_path)
-        logger.log_error(err_msg)
-        raise exceptions.FileFormatError(err_msg)
-
-
-def load_yaml_file(yaml_file):
-    """ load yaml file and check file content format
-    """
-    with io.open(yaml_file, 'r', encoding='utf-8') as stream:
-        yaml_content = yaml.load(stream)
-        _check_format(yaml_file, yaml_content)
-        return yaml_content
-
-
-def load_json_file(json_file):
-    """ load json file and check file content format
-    """
-    with io.open(json_file, encoding='utf-8') as data_file:
-        try:
-            json_content = json.load(data_file)
-        except exceptions.JSONDecodeError:
-            err_msg = u"JSONDecodeError: JSON file format error: {}".format(json_file)
-            logger.log_error(err_msg)
-            raise exceptions.FileFormatError(err_msg)
-
-        _check_format(json_file, json_content)
-        return json_content
-
-
-def load_csv_file(csv_file):
-    """ load csv file and check file content format
-
-    Args:
-        csv_file (str): csv file path, csv file content is like below:
-
-    Returns:
-        list: list of parameters, each parameter is in dict format
-
-    Examples:
-        >>> cat csv_file
-        username,password
-        test1,111111
-        test2,222222
-        test3,333333
-
-        >>> load_csv_file(csv_file)
-        [
-            {'username': 'test1', 'password': '111111'},
-            {'username': 'test2', 'password': '222222'},
-            {'username': 'test3', 'password': '333333'}
-        ]
-
-    """
-    if not os.path.isabs(csv_file):
-        project_working_directory = tests_def_mapping["PWD"] or os.getcwd()
-        # make compatible with Windows/Linux
-        csv_file = os.path.join(project_working_directory, *csv_file.split("/"))
-
-    if not os.path.isfile(csv_file):
-        # file path not exist
-        raise exceptions.CSVNotFound(csv_file)
-
-    csv_content_list = []
-
-    with io.open(csv_file, encoding='utf-8') as csvfile:
-        reader = csv.DictReader(csvfile)
-        for row in reader:
-            csv_content_list.append(row)
-
-    return csv_content_list
-
-
-def load_file(file_path):
-    if not os.path.isfile(file_path):
-        raise exceptions.FileNotFound("{} does not exist.".format(file_path))
-
-    file_suffix = os.path.splitext(file_path)[1].lower()
-    if file_suffix == '.json':
-        return load_json_file(file_path)
-    elif file_suffix in ['.yaml', '.yml']:
-        return load_yaml_file(file_path)
-    elif file_suffix == ".csv":
-        return load_csv_file(file_path)
-    else:
-        # '' or other suffix
-        err_msg = u"Unsupported file format: {}".format(file_path)
-        logger.log_warning(err_msg)
-        return []
-
-
-def load_folder_files(folder_path, recursive=True):
-    """ load folder path, return all files endswith yml/yaml/json in list.
-
-    Args:
-        folder_path (str): specified folder path to load
-        recursive (bool): load files recursively if True
-
-    Returns:
-        list: files endswith yml/yaml/json
-    """
-    if isinstance(folder_path, (list, set)):
-        files = []
-        for path in set(folder_path):
-            files.extend(load_folder_files(path, recursive))
-
-        return files
-
-    if not os.path.exists(folder_path):
-        return []
-
-    file_list = []
-
-    for dirpath, dirnames, filenames in os.walk(folder_path):
-        filenames_list = []
-
-        for filename in filenames:
-            if not filename.endswith(('.yml', '.yaml', '.json')):
-                continue
-
-            filenames_list.append(filename)
-
-        for filename in filenames_list:
-            file_path = os.path.join(dirpath, filename)
-            file_list.append(file_path)
-
-        if not recursive:
-            break
-
-    return file_list
-
-
-def load_dot_env_file(dot_env_path):
-    """ load .env file.
-
-    Args:
-        dot_env_path (str): .env file path
-
-    Returns:
-        dict: environment variables mapping
-
-            {
-                "UserName": "debugtalk",
-                "Password": "123456",
-                "PROJECT_KEY": "ABCDEFGH"
-            }
-
-    Raises:
-        exceptions.FileFormatError: If .env file format is invalid.
-
-    """
-    if not os.path.isfile(dot_env_path):
-        return {}
-
-    logger.log_info("Loading environment variables from {}".format(dot_env_path))
-    env_variables_mapping = {}
-
-    with io.open(dot_env_path, 'r', encoding='utf-8') as fp:
-        for line in fp:
-            # maxsplit=1
-            if "=" in line:
-                variable, value = line.split("=", 1)
-            elif ":" in line:
-                variable, value = line.split(":", 1)
-            else:
-                raise exceptions.FileFormatError(".env format error")
-
-            env_variables_mapping[variable.strip()] = value.strip()
-
-    utils.set_os_environ(env_variables_mapping)
-    return env_variables_mapping
-
-
-def locate_file(start_path, file_name):
-    """ locate filename and return absolute file path.
-        searching will be recursive upward until current working directory.
-
-    Args:
-        start_path (str): start locating path, maybe file path or directory path
-
-    Returns:
-        str: located file path. None if file not found.
-
-    Raises:
-        exceptions.FileNotFound: If failed to locate file.
-
-    """
-    if os.path.isfile(start_path):
-        start_dir_path = os.path.dirname(start_path)
-    elif os.path.isdir(start_path):
-        start_dir_path = start_path
-    else:
-        raise exceptions.FileNotFound("invalid path: {}".format(start_path))
-
-    file_path = os.path.join(start_dir_path, file_name)
-    if os.path.isfile(file_path):
-        return os.path.abspath(file_path)
-
-    # current working directory
-    if os.path.abspath(start_dir_path) in [os.getcwd(), os.path.abspath(os.sep)]:
-        raise exceptions.FileNotFound("{} not found in {}".format(file_name, start_path))
-
-    # locate recursive upward
-    return locate_file(os.path.dirname(start_dir_path), file_name)
-
-
-###############################################################################
-#   debugtalk.py module loader
-###############################################################################
-
-
-def load_module_functions(module):
-    """ load python module functions.
-
-    Args:
-        module: python module
-
-    Returns:
-        dict: functions mapping for specified python module
-
-            {
-                "func1_name": func1,
-                "func2_name": func2
-            }
-
-    """
-    module_functions = {}
-
-    for name, item in vars(module).items():
-        if validator.is_function(item):
-            module_functions[name] = item
-
-    return module_functions
-
-
-def load_builtin_functions():
-    """ load built_in module functions
-    """
-    return load_module_functions(built_in)
+tests_def_mapping = {
+    "api": {},
+    "testcases": {}
+}
 
 
 def load_debugtalk_functions():
@@ -291,19 +30,6 @@ def load_debugtalk_functions():
     return load_module_functions(imported_module)
 
 
-###############################################################################
-#   testcase loader
-###############################################################################
-
-
-project_mapping = {}
-tests_def_mapping = {
-    "PWD": None,
-    "api": {},
-    "testcases": {}
-}
-
-
 def __extend_with_api_ref(raw_testinfo):
     """ extend with api reference
 
@@ -318,7 +44,8 @@ def __extend_with_api_ref(raw_testinfo):
     # 2, api sets file: one file contains a list of api definitions
     if not os.path.isabs(api_name):
         # make compatible with Windows/Linux
-        api_path = os.path.join(tests_def_mapping["PWD"], *api_name.split("/"))
+        pwd = get_project_working_directory()
+        api_path = os.path.join(pwd, *api_name.split("/"))
         if os.path.isfile(api_path):
             # type 1: api is defined in individual file
             api_name = api_path
@@ -338,8 +65,9 @@ def __extend_with_testcase_ref(raw_testinfo):
 
     if testcase_path not in tests_def_mapping["testcases"]:
         # make compatible with Windows/Linux
+        pwd = get_project_working_directory()
         testcase_path = os.path.join(
-            project_mapping["PWD"],
+            pwd,
             *testcase_path.split("/")
         )
         loaded_testcase = load_file(testcase_path)
@@ -650,31 +378,6 @@ def load_test_file(path):
     return loaded_content
 
 
-def load_folder_content(folder_path):
-    """ load api/testcases/testsuites definitions from folder.
-
-    Args:
-        folder_path (str): api/testcases/testsuites files folder.
-
-    Returns:
-        dict: api definition mapping.
-
-            {
-                "tests/api/basic.yml": [
-                    {"api": {"def": "api_login", "request": {}, "validate": []}},
-                    {"api": {"def": "api_logout", "request": {}, "validate": []}}
-                ]
-            }
-
-    """
-    items_mapping = {}
-
-    for file_path in load_folder_files(folder_path):
-        items_mapping[file_path] = load_file(file_path)
-
-    return items_mapping
-
-
 def load_api_folder(api_folder_path):
     """ load api definitions from api folder.
 
@@ -724,7 +427,7 @@ def load_api_folder(api_folder_path):
             for api_item in api_items:
                 key, api_dict = api_item.popitem()
                 api_id = api_dict.get("id") or api_dict.get("def") \
-                    or api_dict.get("name")
+                         or api_dict.get("name")
                 if key != "api" or not api_id:
                     raise exceptions.ParamsError(
                         "Invalid API defined in {}".format(api_file_path))
@@ -746,27 +449,7 @@ def load_api_folder(api_folder_path):
     return api_definition_mapping
 
 
-def locate_debugtalk_py(start_path):
-    """ locate debugtalk.py file
-
-    Args:
-        start_path (str): start locating path,
-            maybe testcase file path or directory path
-
-    Returns:
-        str: debugtalk.py file path, None if not found
-
-    """
-    try:
-        # locate debugtalk.py file.
-        debugtalk_path = locate_file(start_path, "debugtalk.py")
-    except exceptions.FileNotFound:
-        debugtalk_path = None
-
-    return debugtalk_path
-
-
-def load_project_tests(test_path, dot_env_path=None):
+def load_project_data(test_path, dot_env_path=None):
     """ load api, testcases, .env, debugtalk.py functions.
         api/testcases folder is relative to project_working_directory
 
@@ -779,31 +462,9 @@ def load_project_tests(test_path, dot_env_path=None):
             environments and debugtalk.py functions.
 
     """
+    debugtalk_path, project_working_directory = init_project_working_directory(test_path)
 
-    def prepare_path(path):
-        if not os.path.exists(path):
-            err_msg = "path not exist: {}".format(path)
-            logger.log_error(err_msg)
-            raise exceptions.FileNotFound(err_msg)
-
-        if not os.path.isabs(path):
-            path = os.path.join(os.getcwd(), path)
-
-        return path
-
-    test_path = prepare_path(test_path)
-    # locate debugtalk.py file
-    debugtalk_path = locate_debugtalk_py(test_path)
-
-    if debugtalk_path:
-        # The folder contains debugtalk.py will be treated as PWD.
-        project_working_directory = os.path.dirname(debugtalk_path)
-    else:
-        # debugtalk.py not found, use os.getcwd() as PWD.
-        project_working_directory = os.getcwd()
-
-    # add PWD to sys.path
-    sys.path.insert(0, project_working_directory)
+    project_mapping = {}
 
     # load .env file
     # NOTICE:
@@ -821,16 +482,17 @@ def load_project_tests(test_path, dot_env_path=None):
     # locate PWD and load debugtalk.py functions
 
     project_mapping["PWD"] = project_working_directory
-    built_in.PWD = project_working_directory
+    functions.PWD = project_working_directory   # TODO: remove
     project_mapping["functions"] = debugtalk_functions
     project_mapping["test_path"] = test_path
 
     # load api
     tests_def_mapping["api"] = load_api_folder(os.path.join(project_working_directory, "api"))
-    tests_def_mapping["PWD"] = project_working_directory
+
+    return project_mapping
 
 
-def load_tests(path, dot_env_path=None):
+def load_cases(path, dot_env_path=None):
     """ load testcases from file path, extend and merge with api/testcase definitions.
 
     Args:
@@ -883,9 +545,9 @@ def load_tests(path, dot_env_path=None):
             }
 
     """
-    load_project_tests(path, dot_env_path)
+
     tests_mapping = {
-        "project_mapping": project_mapping
+        "project_mapping": load_project_data(path, dot_env_path)
     }
 
     def __load_file_content(path):
diff --git a/httprunner/loader/check.py b/httprunner/loader/check.py
new file mode 100644
index 00000000..27e647a4
--- /dev/null
+++ b/httprunner/loader/check.py
@@ -0,0 +1,191 @@
+import io
+import json
+import os
+import types
+
+from httprunner import logger, exceptions
+
+
+# TODO: validate data format with JSON schema
+
+def is_testcase(data_structure):
+    """ check if data_structure is a testcase.
+
+    Args:
+        data_structure (dict): testcase should always be in the following data structure:
+
+            {
+                "config": {
+                    "name": "desc1",
+                    "variables": [],    # optional
+                    "request": {}       # optional
+                },
+                "teststeps": [
+                    test_dict1,
+                    {   # test_dict2
+                        'name': 'test step desc2',
+                        'variables': [],    # optional
+                        'extract': [],      # optional
+                        'validate': [],
+                        'request': {},
+                        'function_meta': {}
+                    }
+                ]
+            }
+
+    Returns:
+        bool: True if data_structure is valid testcase, otherwise False.
+
+    """
+    # TODO: replace with JSON schema validation
+    if not isinstance(data_structure, dict):
+        return False
+
+    if "teststeps" not in data_structure:
+        return False
+
+    if not isinstance(data_structure["teststeps"], list):
+        return False
+
+    return True
+
+
+def is_testcases(data_structure):
+    """ check if data_structure is testcase or testcases list.
+
+    Args:
+        data_structure (dict): testcase(s) should always be in the following data structure:
+            {
+                "project_mapping": {
+                    "PWD": "XXXXX",
+                    "functions": {},
+                    "env": {}
+                },
+                "testcases": [
+                    {   # testcase data structure
+                        "config": {
+                            "name": "desc1",
+                            "path": "testcase1_path",
+                            "variables": [],                    # optional
+                        },
+                        "teststeps": [
+                            # test data structure
+                            {
+                                'name': 'test step desc1',
+                                'variables': [],    # optional
+                                'extract': [],      # optional
+                                'validate': [],
+                                'request': {}
+                            },
+                            test_dict_2   # another test dict
+                        ]
+                    },
+                    testcase_dict_2     # another testcase dict
+                ]
+            }
+
+    Returns:
+        bool: True if data_structure is valid testcase(s), otherwise False.
+
+    """
+    if not isinstance(data_structure, dict):
+        return False
+
+    if "testcases" not in data_structure:
+        return False
+
+    testcases = data_structure["testcases"]
+    if not isinstance(testcases, list):
+        return False
+
+    for item in testcases:
+        if not is_testcase(item):
+            return False
+
+    return True
+
+
+def is_testcase_path(path):
+    """ check if path is testcase path or path list.
+
+    Args:
+        path (str/list): file path or file path list.
+
+    Returns:
+        bool: True if path is valid file path or path list, otherwise False.
+
+    """
+    if not isinstance(path, (str, list)):
+        return False
+
+    if isinstance(path, list):
+        for p in path:
+            if not is_testcase_path(p):
+                return False
+
+    if isinstance(path, str):
+        if not os.path.exists(path):
+            return False
+
+    return True
+
+
+def check_testcase_format(file_path, content):
+    """ check testcase format if valid
+    """
+    # TODO: replace with JSON schema validation
+    if not content:
+        # testcase file content is empty
+        err_msg = u"Testcase file content is empty: {}".format(file_path)
+        logger.log_error(err_msg)
+        raise exceptions.FileFormatError(err_msg)
+
+    elif not isinstance(content, (list, dict)):
+        # testcase file content does not match testcase format
+        err_msg = u"Testcase file content format invalid: {}".format(file_path)
+        logger.log_error(err_msg)
+        raise exceptions.FileFormatError(err_msg)
+
+
+def validate_json_file(file_list):
+    """ validate JSON testcase format
+    """
+    for json_file in set(file_list):
+        if not json_file.endswith(".json"):
+            logger.log_warning("Only JSON file format can be validated, skip: {}".format(json_file))
+            continue
+
+        logger.color_print("Start to validate JSON file: {}".format(json_file), "GREEN")
+
+        with io.open(json_file) as stream:
+            try:
+                json.load(stream)
+            except ValueError as e:
+                raise SystemExit(e)
+
+        print("OK")
+
+
+def is_function(item):
+    """ Takes item object, returns True if it is a function.
+    """
+    return isinstance(item, types.FunctionType)
+
+
+def is_variable(tup):
+    """ Takes (name, object) tuple, returns True if it is a variable.
+    """
+    name, item = tup
+    if callable(item):
+        # function or class
+        return False
+
+    if isinstance(item, types.ModuleType):
+        # imported module
+        return False
+
+    if name.startswith("_"):
+        # private property
+        return False
+
+    return True
diff --git a/httprunner/loader/load.py b/httprunner/loader/load.py
new file mode 100644
index 00000000..1fac6599
--- /dev/null
+++ b/httprunner/loader/load.py
@@ -0,0 +1,241 @@
+import csv
+import io
+import json
+import os
+
+import yaml
+
+from httprunner import builtin
+from httprunner import exceptions, logger, utils
+from httprunner.loader.check import check_testcase_format, is_function
+from httprunner.loader.locate import get_project_working_directory
+
+try:
+    # PyYAML version >= 5.1
+    # ref: https://github.com/yaml/pyyaml/wiki/PyYAML-yaml.load(input)-Deprecation
+    yaml.warnings({'YAMLLoadWarning': False})
+except AttributeError:
+    pass
+
+
+def _load_yaml_file(yaml_file):
+    """ load yaml file and check file content format
+    """
+    with io.open(yaml_file, 'r', encoding='utf-8') as stream:
+        yaml_content = yaml.load(stream)
+        check_testcase_format(yaml_file, yaml_content)
+        return yaml_content
+
+
+def _load_json_file(json_file):
+    """ load json file and check file content format
+    """
+    with io.open(json_file, encoding='utf-8') as data_file:
+        try:
+            json_content = json.load(data_file)
+        except exceptions.JSONDecodeError:
+            err_msg = u"JSONDecodeError: JSON file format error: {}".format(json_file)
+            logger.log_error(err_msg)
+            raise exceptions.FileFormatError(err_msg)
+
+        check_testcase_format(json_file, json_content)
+        return json_content
+
+
+def load_csv_file(csv_file):
+    """ load csv file and check file content format
+
+    Args:
+        csv_file (str): csv file path, csv file content is like below:
+
+    Returns:
+        list: list of parameters, each parameter is in dict format
+
+    Examples:
+        >>> cat csv_file
+        username,password
+        test1,111111
+        test2,222222
+        test3,333333
+
+        >>> load_csv_file(csv_file)
+        [
+            {'username': 'test1', 'password': '111111'},
+            {'username': 'test2', 'password': '222222'},
+            {'username': 'test3', 'password': '333333'}
+        ]
+
+    """
+    if not os.path.isabs(csv_file):
+        pwd = get_project_working_directory()
+        # make compatible with Windows/Linux
+        csv_file = os.path.join(pwd, *csv_file.split("/"))
+
+    if not os.path.isfile(csv_file):
+        # file path not exist
+        raise exceptions.CSVNotFound(csv_file)
+
+    csv_content_list = []
+
+    with io.open(csv_file, encoding='utf-8') as csvfile:
+        reader = csv.DictReader(csvfile)
+        for row in reader:
+            csv_content_list.append(row)
+
+    return csv_content_list
+
+
+def load_file(file_path):
+    if not os.path.isfile(file_path):
+        raise exceptions.FileNotFound("{} does not exist.".format(file_path))
+
+    file_suffix = os.path.splitext(file_path)[1].lower()
+    if file_suffix == '.json':
+        return _load_json_file(file_path)
+    elif file_suffix in ['.yaml', '.yml']:
+        return _load_yaml_file(file_path)
+    elif file_suffix == ".csv":
+        return load_csv_file(file_path)
+    else:
+        # '' or other suffix
+        err_msg = u"Unsupported file format: {}".format(file_path)
+        logger.log_warning(err_msg)
+        return []
+
+
+def load_folder_files(folder_path, recursive=True):
+    """ load folder path, return all files endswith yml/yaml/json in list.
+
+    Args:
+        folder_path (str): specified folder path to load
+        recursive (bool): load files recursively if True
+
+    Returns:
+        list: files endswith yml/yaml/json
+    """
+    if isinstance(folder_path, (list, set)):
+        files = []
+        for path in set(folder_path):
+            files.extend(load_folder_files(path, recursive))
+
+        return files
+
+    if not os.path.exists(folder_path):
+        return []
+
+    file_list = []
+
+    for dirpath, dirnames, filenames in os.walk(folder_path):
+        filenames_list = []
+
+        for filename in filenames:
+            if not filename.endswith(('.yml', '.yaml', '.json')):
+                continue
+
+            filenames_list.append(filename)
+
+        for filename in filenames_list:
+            file_path = os.path.join(dirpath, filename)
+            file_list.append(file_path)
+
+        if not recursive:
+            break
+
+    return file_list
+
+
+def load_dot_env_file(dot_env_path):
+    """ load .env file.
+
+    Args:
+        dot_env_path (str): .env file path
+
+    Returns:
+        dict: environment variables mapping
+
+            {
+                "UserName": "debugtalk",
+                "Password": "123456",
+                "PROJECT_KEY": "ABCDEFGH"
+            }
+
+    Raises:
+        exceptions.FileFormatError: If .env file format is invalid.
+
+    """
+    if not os.path.isfile(dot_env_path):
+        return {}
+
+    logger.log_info("Loading environment variables from {}".format(dot_env_path))
+    env_variables_mapping = {}
+
+    with io.open(dot_env_path, 'r', encoding='utf-8') as fp:
+        for line in fp:
+            # maxsplit=1
+            if "=" in line:
+                variable, value = line.split("=", 1)
+            elif ":" in line:
+                variable, value = line.split(":", 1)
+            else:
+                raise exceptions.FileFormatError(".env format error")
+
+            env_variables_mapping[variable.strip()] = value.strip()
+
+    utils.set_os_environ(env_variables_mapping)
+    return env_variables_mapping
+
+
+def load_folder_content(folder_path):
+    """ load api/testcases/testsuites definitions from folder.
+
+    Args:
+        folder_path (str): api/testcases/testsuites files folder.
+
+    Returns:
+        dict: api definition mapping.
+
+            {
+                "tests/api/basic.yml": [
+                    {"api": {"def": "api_login", "request": {}, "validate": []}},
+                    {"api": {"def": "api_logout", "request": {}, "validate": []}}
+                ]
+            }
+
+    """
+    items_mapping = {}
+
+    for file_path in load_folder_files(folder_path):
+        items_mapping[file_path] = load_file(file_path)
+
+    return items_mapping
+
+
+def load_module_functions(module):
+    """ load python module functions.
+
+    Args:
+        module: python module
+
+    Returns:
+        dict: functions mapping for specified python module
+
+            {
+                "func1_name": func1,
+                "func2_name": func2
+            }
+
+    """
+    module_functions = {}
+
+    for name, item in vars(module).items():
+        if is_function(item):
+            module_functions[name] = item
+
+    return module_functions
+
+
+def load_builtin_functions():
+    """ load builtin module functions
+    """
+    return load_module_functions(builtin)
+
diff --git a/httprunner/loader/locate.py b/httprunner/loader/locate.py
new file mode 100644
index 00000000..0ac21161
--- /dev/null
+++ b/httprunner/loader/locate.py
@@ -0,0 +1,110 @@
+import os
+import sys
+
+from httprunner import exceptions, logger
+
+project_working_directory = None
+
+
+def locate_file(start_path, file_name):
+    """ locate filename and return absolute file path.
+        searching will be recursive upward until current working directory.
+
+    Args:
+        file_name (str): target locate file name
+        start_path (str): start locating path, maybe file path or directory path
+
+    Returns:
+        str: located file path. None if file not found.
+
+    Raises:
+        exceptions.FileNotFound: If failed to locate file.
+
+    """
+    if os.path.isfile(start_path):
+        start_dir_path = os.path.dirname(start_path)
+    elif os.path.isdir(start_path):
+        start_dir_path = start_path
+    else:
+        raise exceptions.FileNotFound("invalid path: {}".format(start_path))
+
+    file_path = os.path.join(start_dir_path, file_name)
+    if os.path.isfile(file_path):
+        return os.path.abspath(file_path)
+
+    # current working directory
+    if os.path.abspath(start_dir_path) in [os.getcwd(), os.path.abspath(os.sep)]:
+        raise exceptions.FileNotFound("{} not found in {}".format(file_name, start_path))
+
+    # locate recursive upward
+    return locate_file(os.path.dirname(start_dir_path), file_name)
+
+
+def locate_debugtalk_py(start_path):
+    """ locate debugtalk.py file
+
+    Args:
+        start_path (str): start locating path,
+            maybe testcase file path or directory path
+
+    Returns:
+        str: debugtalk.py file path, None if not found
+
+    """
+    try:
+        # locate debugtalk.py file.
+        debugtalk_path = locate_file(start_path, "debugtalk.py")
+    except exceptions.FileNotFound:
+        debugtalk_path = None
+
+    return debugtalk_path
+
+
+def init_project_working_directory(test_path):
+    """ this should be called at startup
+        init_project_working_directory <- load_project_data <- load_cases <- run
+
+    Args:
+        test_path: specified testfile path
+
+    Returns:
+        (str, str): debugtalk.py path, project_working_directory
+
+    """
+
+    def prepare_path(path):
+        if not os.path.exists(path):
+            err_msg = "path not exist: {}".format(path)
+            logger.log_error(err_msg)
+            raise exceptions.FileNotFound(err_msg)
+
+        if not os.path.isabs(path):
+            path = os.path.join(os.getcwd(), path)
+
+        return path
+
+    test_path = prepare_path(test_path)
+
+    # locate debugtalk.py file
+    debugtalk_path = locate_debugtalk_py(test_path)
+
+    global project_working_directory
+    if debugtalk_path:
+        # The folder contains debugtalk.py will be treated as PWD.
+        project_working_directory = os.path.dirname(debugtalk_path)
+    else:
+        # debugtalk.py not found, use os.getcwd() as PWD.
+        project_working_directory = os.getcwd()
+
+    # add PWD to sys.path
+    sys.path.insert(0, project_working_directory)
+
+    return debugtalk_path, project_working_directory
+
+
+def get_project_working_directory():
+    global project_working_directory
+    if project_working_directory is None:
+        raise exceptions.MyBaseFailure("loader.load_cases() has not been called!")
+
+    return project_working_directory
diff --git a/httprunner/parser.py b/httprunner/parser.py
index 29b0a666..f439a7b0 100644
--- a/httprunner/parser.py
+++ b/httprunner/parser.py
@@ -2,9 +2,11 @@
 
 import ast
 import builtins
+import collections
+import json
 import re
 
-from httprunner import exceptions, utils, validator
+from httprunner import exceptions, utils, loader
 from httprunner.compat import basestring, numeric_types, str
 
 # use $$ to escape $ notation
@@ -218,6 +220,166 @@ def parse_parameters(parameters, variables_mapping=None, functions_mapping=None)
     return utils.gen_cartesian_product(*parsed_parameters_list)
 
 
+def get_uniform_comparator(comparator):
+    """ convert comparator alias to uniform name
+    """
+    if comparator in ["eq", "equals", "==", "is"]:
+        return "equals"
+    elif comparator in ["lt", "less_than"]:
+        return "less_than"
+    elif comparator in ["le", "less_than_or_equals"]:
+        return "less_than_or_equals"
+    elif comparator in ["gt", "greater_than"]:
+        return "greater_than"
+    elif comparator in ["ge", "greater_than_or_equals"]:
+        return "greater_than_or_equals"
+    elif comparator in ["ne", "not_equals"]:
+        return "not_equals"
+    elif comparator in ["str_eq", "string_equals"]:
+        return "string_equals"
+    elif comparator in ["len_eq", "length_equals", "count_eq"]:
+        return "length_equals"
+    elif comparator in ["len_gt", "count_gt", "length_greater_than", "count_greater_than"]:
+        return "length_greater_than"
+    elif comparator in ["len_ge", "count_ge", "length_greater_than_or_equals",
+                        "count_greater_than_or_equals"]:
+        return "length_greater_than_or_equals"
+    elif comparator in ["len_lt", "count_lt", "length_less_than", "count_less_than"]:
+        return "length_less_than"
+    elif comparator in ["len_le", "count_le", "length_less_than_or_equals",
+                        "count_less_than_or_equals"]:
+        return "length_less_than_or_equals"
+    else:
+        return comparator
+
+
+def uniform_validator(validator):
+    """ unify validator
+
+    Args:
+        validator (dict): validator maybe in two formats:
+
+            format1: this is kept for compatiblity with the previous versions.
+                {"check": "status_code", "comparator": "eq", "expect": 201}
+                {"check": "$resp_body_success", "comparator": "eq", "expect": True}
+            format2: recommended new version, {comparator: [check_item, expected_value]}
+                {'eq': ['status_code', 201]}
+                {'eq': ['$resp_body_success', True]}
+
+    Returns
+        dict: validator info
+
+            {
+                "check": "status_code",
+                "expect": 201,
+                "comparator": "equals"
+            }
+
+    """
+    if not isinstance(validator, dict):
+        raise exceptions.ParamsError("invalid validator: {}".format(validator))
+
+    if "check" in validator and "expect" in validator:
+        # format1
+        check_item = validator["check"]
+        expect_value = validator["expect"]
+        comparator = validator.get("comparator", "eq")
+
+    elif len(validator) == 1:
+        # format2
+        comparator = list(validator.keys())[0]
+        compare_values = validator[comparator]
+
+        if not isinstance(compare_values, list) or len(compare_values) != 2:
+            raise exceptions.ParamsError("invalid validator: {}".format(validator))
+
+        check_item, expect_value = compare_values
+
+    else:
+        raise exceptions.ParamsError("invalid validator: {}".format(validator))
+
+    # uniform comparator, e.g. lt => less_than, eq => equals
+    comparator = get_uniform_comparator(comparator)
+
+    return {
+        "check": check_item,
+        "expect": expect_value,
+        "comparator": comparator
+    }
+
+
+def _convert_validators_to_mapping(validators):
+    """ convert validators list to mapping.
+
+    Args:
+        validators (list): validators in list
+
+    Returns:
+        dict: validators mapping, use (check, comparator) as key.
+
+    Examples:
+        >>> validators = [
+            {"check": "v1", "expect": 201, "comparator": "eq"},
+            {"check": {"b": 1}, "expect": 200, "comparator": "eq"}
+        ]
+        >>> print(_convert_validators_to_mapping(validators))
+        {
+            ("v1", "eq"): {"check": "v1", "expect": 201, "comparator": "eq"},
+            ('{"b": 1}', "eq"): {"check": {"b": 1}, "expect": 200, "comparator": "eq"}
+        }
+
+    """
+    validators_mapping = {}
+
+    for validator in validators:
+        if not isinstance(validator["check"], collections.Hashable):
+            check = json.dumps(validator["check"])
+        else:
+            check = validator["check"]
+
+        key = (check, validator["comparator"])
+        validators_mapping[key] = validator
+
+    return validators_mapping
+
+
+def extend_validators(raw_validators, override_validators):
+    """ extend raw_validators with override_validators.
+        override_validators will merge and override raw_validators.
+
+    Args:
+        raw_validators (dict):
+        override_validators (dict):
+
+    Returns:
+        list: extended validators
+
+    Examples:
+        >>> raw_validators = [{'eq': ['v1', 200]}, {"check": "s2", "expect": 16, "comparator": "len_eq"}]
+        >>> override_validators = [{"check": "v1", "expect": 201}, {'len_eq': ['s3', 12]}]
+        >>> extend_validators(raw_validators, override_validators)
+            [
+                {"check": "v1", "expect": 201, "comparator": "eq"},
+                {"check": "s2", "expect": 16, "comparator": "len_eq"},
+                {"check": "s3", "expect": 12, "comparator": "len_eq"}
+            ]
+
+    """
+
+    if not raw_validators:
+        return override_validators
+
+    elif not override_validators:
+        return raw_validators
+
+    else:
+        def_validators_mapping = _convert_validators_to_mapping(raw_validators)
+        ref_validators_mapping = _convert_validators_to_mapping(override_validators)
+
+        def_validators_mapping.update(ref_validators_mapping)
+        return list(def_validators_mapping.values())
+
+
 ###############################################################################
 ##  parse content with variables and functions mapping
 ###############################################################################
@@ -247,8 +409,8 @@ def get_mapping_function(function_name, functions_mapping):
         if not found, then try to check if builtin function.
 
     Args:
-        variable_name (str): variable name
-        variables_mapping (dict): variables mapping
+        function_name (str): function name
+        functions_mapping (dict): functions mapping
 
     Returns:
         mapping function object.
@@ -261,7 +423,6 @@ def get_mapping_function(function_name, functions_mapping):
         return functions_mapping[function_name]
 
     elif function_name in ["parameterize", "P"]:
-        from httprunner import loader
         return loader.load_csv_file
 
     elif function_name in ["environ", "ENV"]:
@@ -269,7 +430,6 @@ def get_mapping_function(function_name, functions_mapping):
 
     try:
         # check if HttpRunner builtin functions
-        from httprunner import loader
         built_in_functions = loader.load_builtin_functions()
         return built_in_functions[function_name]
     except KeyError:
@@ -338,6 +498,7 @@ def parse_function_params(params):
 class LazyFunction(object):
     """ call function lazily.
     """
+
     def __init__(self, function_meta, functions_mapping=None, check_variables_set=None):
         """ init LazyFunction object with function_meta
 
@@ -410,7 +571,7 @@ class LazyFunction(object):
         return "LazyFunction({}({}))".format(self.func_name, args_string)
 
     def __prepare_cache_key(self, args, kwargs):
-        return (self.func_name, repr(args), repr(kwargs))
+        return self.func_name, repr(args), repr(kwargs)
 
     def to_value(self, variables_mapping=None):
         """ parse lazy data with evaluated variables mapping.
@@ -431,6 +592,7 @@ cached_functions_mapping = {}
 class LazyString(object):
     """ evaluate string lazily.
     """
+
     def __init__(self, raw_string, functions_mapping=None, check_variables_set=None, cached=False):
         """ make raw_string as lazy object with functions_mapping
             check if any variable undefined in check_variables_set
@@ -511,7 +673,7 @@ class LazyString(object):
             curr_position = match_start_position
             try:
                 # find next $ location
-                match_start_position = raw_string.index("$", curr_position+1)
+                match_start_position = raw_string.index("$", curr_position + 1)
                 remain_string = raw_string[curr_position:match_start_position]
             except ValueError:
                 remain_string = raw_string[curr_position:]
@@ -786,11 +948,11 @@ def _extend_with_api(test_dict, api_def_dict):
     # merge & override validators TODO: relocate
     def_raw_validators = api_def_dict.pop("validate", [])
     def_validators = [
-        validator.uniform_validator(_validator)
+        uniform_validator(_validator)
         for _validator in def_raw_validators
     ]
     ref_validators = test_dict.pop("validate", [])
-    test_dict["validate"] = validator.extend_validators(
+    test_dict["validate"] = extend_validators(
         def_validators,
         ref_validators
     )
@@ -843,7 +1005,8 @@ def _extend_with_testcase(test_dict, testcase_def_dict):
     """
     # override testcase config variables
     testcase_def_dict["config"].setdefault("variables", {})
-    testcase_def_variables = utils.ensure_mapping_format(testcase_def_dict["config"].get("variables", {}))
+    testcase_def_variables = utils.ensure_mapping_format(
+        testcase_def_dict["config"].get("variables", {}))
     testcase_def_variables.update(test_dict.pop("variables", {}))
     testcase_def_dict["config"]["variables"] = testcase_def_variables
 
@@ -855,8 +1018,8 @@ def _extend_with_testcase(test_dict, testcase_def_dict):
 
     # override name
     test_name = test_dict.pop("name", None) \
-        or testcase_def_dict["config"].pop("name", None) \
-        or "testcase name undefined"
+                or testcase_def_dict["config"].pop("name", None) \
+                or "testcase name undefined"
 
     # override testcase config name, output, etc.
     testcase_def_dict["config"].update(test_dict)
@@ -875,7 +1038,8 @@ def __prepare_config(config, project_mapping, session_variables_set=None):
     override_variables = utils.deepcopy_dict(project_mapping.get("variables", {}))
     functions = project_mapping.get("functions", {})
 
-    if isinstance(raw_config_variables, basestring) and function_regex_compile.match(raw_config_variables):
+    if isinstance(raw_config_variables, basestring) and function_regex_compile.match(
+            raw_config_variables):
         # config variables are generated by calling function
         # e.g.
         # "config": {
@@ -946,7 +1110,7 @@ def __prepare_testcase_tests(tests, config, project_mapping, session_variables_s
         if "validate" in test_dict:
             ref_raw_validators = test_dict.pop("validate", [])
             test_dict["validate"] = [
-                validator.uniform_validator(_validator)
+                uniform_validator(_validator)
                 for _validator in ref_raw_validators
             ]
 
diff --git a/httprunner/plugins/locusts/utils.py b/httprunner/plugins/locusts/utils.py
index ab7cef91..e1d5d881 100644
--- a/httprunner/plugins/locusts/utils.py
+++ b/httprunner/plugins/locusts/utils.py
@@ -16,7 +16,7 @@ def prepare_locust_tests(path):
             ]
 
     """
-    tests_mapping = loader.load_tests(path)
+    tests_mapping = loader.load_cases(path)
     testcases = parser.parse_tests(tests_mapping)
 
     locust_tests = []
diff --git a/httprunner/runner.py b/httprunner/runner.py
index 13f0a9c9..6aa41fe9 100644
--- a/httprunner/runner.py
+++ b/httprunner/runner.py
@@ -5,6 +5,7 @@ from unittest.case import SkipTest
 from httprunner import exceptions, logger, response, utils
 from httprunner.client import HttpSession
 from httprunner.context import SessionContext
+from httprunner.validator import Validator
 
 
 class Runner(object):
@@ -62,7 +63,6 @@ class Runner(object):
         """
         self.verify = config.get("verify", True)
         self.export = config.get("export") or config.get("output", [])
-        self.validation_results = []
         config_variables = config.get("variables", {})
 
         # testcase setup hooks
@@ -86,19 +86,8 @@ class Runner(object):
         if not isinstance(self.http_client_session, HttpSession):
             return
 
-        self.validation_results = []
         self.http_client_session.init_meta_data()
 
-    def __get_test_data(self):
-        """ get request/response data and validate results
-        """
-        if not isinstance(self.http_client_session, HttpSession):
-            return
-
-        meta_data = self.http_client_session.meta_data
-        meta_data["validators"] = self.validation_results
-        return meta_data
-
     def _handle_skip_feature(self, test_dict):
         """ handle skip feature for test
             - skip: skip current test unconditionally
@@ -244,7 +233,8 @@ class Runner(object):
             raise exceptions.ParamsError(err_msg)
 
         logger.log_info("{method} {url}".format(method=method, url=parsed_url))
-        logger.log_debug("request kwargs(raw): {kwargs}".format(kwargs=parsed_test_request))
+        logger.log_debug(
+            "request kwargs(raw): {kwargs}".format(kwargs=parsed_test_request))
 
         # request
         resp = self.http_client_session.request(
@@ -269,9 +259,18 @@ class Runner(object):
 
         # validate
         validators = test_dict.get("validate") or test_dict.get("validators") or []
+        validate_script = test_dict.get("validate_script", [])
+        if validate_script:
+            validators.append({
+                "type": "python_script",
+                "script": validate_script
+            })
+
+        validator = Validator(self.session_context, resp_obj)
         try:
-            self.session_context.validate(validators, resp_obj)
-        except (exceptions.ParamsError, exceptions.ValidationFailure, exceptions.ExtractFailure):
+            validator.validate(validators)
+        except (exceptions.ParamsError,
+                exceptions.ValidationFailure, exceptions.ExtractFailure):
             err_msg = "{} DETAILED REQUEST & RESPONSE {}\n".format("*" * 32, "*" * 32)
 
             # log request
@@ -295,7 +294,9 @@ class Runner(object):
             raise
 
         finally:
-            self.validation_results = self.session_context.validation_results
+            # get request/response data and validate results
+            self.meta_datas = getattr(self.http_client_session, "meta_data", {})
+            self.meta_datas["validators"] = validator.validation_results
 
     def _run_testcase(self, testcase_dict):
         """ run single testcase.
@@ -380,8 +381,6 @@ class Runner(object):
                 self.exception_request_type = test_dict["request"]["method"]
                 self.exception_name = test_dict.get("name")
                 raise
-            finally:
-                self.meta_datas = self.__get_test_data()
 
     def export_variables(self, output_variables_list):
         """ export current testcase variables
@@ -392,8 +391,8 @@ class Runner(object):
         for variable in output_variables_list:
             if variable not in variables_mapping:
                 logger.log_warning(
-                    "variable '{}' can not be found in variables mapping, failed to export!"\
-                        .format(variable)
+                    "variable '{}' can not be found in variables mapping, "
+                    "failed to export!".format(variable)
                 )
                 continue
 
diff --git a/httprunner/static/report_template.html b/httprunner/static/report_template.html
index 633b97c5..209c18ae 100644
--- a/httprunner/static/report_template.html
+++ b/httprunner/static/report_template.html
@@ -279,15 +279,17 @@
               {% endfor %}
 
               <h3>Validators:</h3>
-              <div style="overflow: auto">
-                  <table>
+                <div style="overflow: auto">
+                {% set validate_extractors = meta_data.validators.validate_extractor %}
+                {% if validate_extractors %}
+                <table>
                     <tr>
                       <th>check</th>
                       <th>comparator</th>
                       <th>expect value</th>
                       <th>actual value</th>
                     </tr>
-                    {% for validator in meta_data.validators %}
+                    {% for validator in validate_extractors %}
                     <tr>
                       {% if validator.check_result == "pass" %}
                       <td class="passed">
@@ -303,7 +305,27 @@
                       <td>{{validator.check_value | e}}</td>
                     </tr>
                     {% endfor %}
-                  </table>
+                </table>
+                {% endif %}
+
+                {% set validate_script = meta_data.validators.validate_script %}
+                {% if validate_script %}
+                    <table>
+                        <tr>
+                            <th>validate script</th><th>exception</th>
+                        </tr>
+                        <tr>
+                            <td>{{validate_script.validate_script | safe}}</td>
+                            {% if validate_script.check_result == "pass" %}
+                            <td class="passed">
+                            {% elif validate_script.check_result == "fail" %}
+                            <td class="failed">
+                            {% endif %}
+                            {{validate_script.exception}}
+                            </td>
+                        </tr>
+                    </table>
+                {% endif %}
               </div>
 
               <h3>Statistics:</h3>
diff --git a/httprunner/utils.py b/httprunner/utils.py
index 928b4882..efb38835 100644
--- a/httprunner/utils.py
+++ b/httprunner/utils.py
@@ -119,52 +119,6 @@ def query_json(json_content, query, delimiter='.'):
     return json_content
 
 
-def deep_update_dict(origin_dict, override_dict):
-    """ update origin dict with override dict recursively
-    e.g. origin_dict = {'a': 1, 'b': {'c': 2, 'd': 4}}
-         override_dict = {'b': {'c': 3}}
-    return: {'a': 1, 'b': {'c': 3, 'd': 4}}
-    """
-    if not override_dict:
-        return origin_dict
-
-    for key, val in override_dict.items():
-        if isinstance(val, dict):
-            tmp = deep_update_dict(origin_dict.get(key, {}), val)
-            origin_dict[key] = tmp
-        elif val is None:
-            # fix #64: when headers in test is None, it should inherit from config
-            continue
-        else:
-            origin_dict[key] = override_dict[key]
-
-    return origin_dict
-
-
-def convert_dict_to_params(src_dict):
-    """ convert dict to params string
-
-    Args:
-        src_dict (dict): source mapping data structure
-
-    Returns:
-        str: string params data
-
-    Examples:
-        >>> src_dict = {
-            "a": 1,
-            "b": 2
-        }
-        >>> convert_dict_to_params(src_dict)
-        >>> "a=1&b=2"
-
-    """
-    return "&".join([
-        "{}={}".format(key, value)
-        for key, value in src_dict.items()
-    ])
-
-
 def lower_dict_keys(origin_dict):
     """ convert keys in dict to lower case
 
diff --git a/httprunner/validator.py b/httprunner/validator.py
index f8a4e4f2..3a821047 100644
--- a/httprunner/validator.py
+++ b/httprunner/validator.py
@@ -1,347 +1,191 @@
 # encoding: utf-8
-import collections
-import io
-import json
-import os
-import types
 
-from httprunner import exceptions, logger
-
-""" validate data format
-TODO: refactor with JSON schema validate
-"""
+from httprunner import exceptions, logger, parser
 
 
-def is_testcase(data_structure):
-    """ check if data_structure is a testcase.
+class Validator(object):
+    """Validate tests
 
-    Args:
-        data_structure (dict): testcase should always be in the following data structure:
-
-            {
-                "config": {
-                    "name": "desc1",
-                    "variables": [],    # optional
-                    "request": {}       # optional
-                },
-                "teststeps": [
-                    test_dict1,
-                    {   # test_dict2
-                        'name': 'test step desc2',
-                        'variables': [],    # optional
-                        'extract': [],      # optional
-                        'validate': [],
-                        'request': {},
-                        'function_meta': {}
-                    }
-                ]
-            }
-
-    Returns:
-        bool: True if data_structure is valid testcase, otherwise False.
+    Attributes:
+        validation_results (dict): store validation results,
+            including validate_extractor and validate_script.
 
     """
-    # TODO: replace with JSON schema validation
-    if not isinstance(data_structure, dict):
-        return False
 
-    if "teststeps" not in data_structure:
-        return False
+    def __init__(self, session_context, resp_obj):
+        """ initialize a Validator for each teststep (API request)
 
-    if not isinstance(data_structure["teststeps"], list):
-        return False
+        Args:
+            session_context: HttpRunner session context
+            resp_obj: ResponseObject instance
+        """
+        self.session_context = session_context
+        self.resp_obj = resp_obj
+        self.validation_results = {}
 
-    return True
+    def __eval_validator_check(self, check_item):
+        """ evaluate check item in validator.
 
+        Args:
+            check_item: check_item should only be the following 5 formats:
+                1, variable reference, e.g. $token
+                2, function reference, e.g. ${is_status_code_200($status_code)}
+                3, dict or list, maybe containing variable/function reference, e.g. {"var": "$abc"}
+                4, string joined by delimiter. e.g. "status_code", "headers.content-type"
+                5, regex string, e.g. "LB[\d]*(.*)RB[\d]*"
 
-def is_testcases(data_structure):
-    """ check if data_structure is testcase or testcases list.
+        """
+        if isinstance(check_item, (dict, list)) \
+                or isinstance(check_item, parser.LazyString):
+            # format 1/2/3
+            check_value = self.session_context.eval_content(check_item)
+        else:
+            # format 4/5
+            check_value = self.resp_obj.extract_field(check_item)
 
-    Args:
-        data_structure (dict): testcase(s) should always be in the following data structure:
-            {
-                "project_mapping": {
-                    "PWD": "XXXXX",
-                    "functions": {},
-                    "env": {}
-                },
-                "testcases": [
-                    {   # testcase data structure
-                        "config": {
-                            "name": "desc1",
-                            "path": "testcase1_path",
-                            "variables": [],                    # optional
-                        },
-                        "teststeps": [
-                            # test data structure
-                            {
-                                'name': 'test step desc1',
-                                'variables': [],    # optional
-                                'extract': [],      # optional
-                                'validate': [],
-                                'request': {}
-                            },
-                            test_dict_2   # another test dict
-                        ]
-                    },
-                    testcase_dict_2     # another testcase dict
-                ]
-            }
+        return check_value
 
-    Returns:
-        bool: True if data_structure is valid testcase(s), otherwise False.
+    def __eval_validator_expect(self, expect_item):
+        """ evaluate expect item in validator.
 
-    """
-    if not isinstance(data_structure, dict):
-        return False
+        Args:
+            expect_item: expect_item should only be in 2 types:
+                1, variable reference, e.g. $expect_status_code
+                2, actual value, e.g. 200
 
-    if "testcases" not in data_structure:
-        return False
+        """
+        expect_value = self.session_context.eval_content(expect_item)
+        return expect_value
 
-    testcases = data_structure["testcases"]
-    if not isinstance(testcases, list):
-        return False
-
-    for item in testcases:
-        if not is_testcase(item):
-            return False
-
-    return True
-
-
-def is_testcase_path(path):
-    """ check if path is testcase path or path list.
-
-    Args:
-        path (str/list): file path or file path list.
-
-    Returns:
-        bool: True if path is valid file path or path list, otherwise False.
-
-    """
-    if not isinstance(path, (str, list)):
-        return False
-
-    if isinstance(path, list):
-        for p in path:
-            if not is_testcase_path(p):
-                return False
-
-    if isinstance(path, str):
-        if not os.path.exists(path):
-            return False
-
-    return True
-
-
-###############################################################################
-##   testcase validator utils
-###############################################################################
-
-def get_uniform_comparator(comparator):
-    """ convert comparator alias to uniform name
-    """
-    if comparator in ["eq", "equals", "==", "is"]:
-        return "equals"
-    elif comparator in ["lt", "less_than"]:
-        return "less_than"
-    elif comparator in ["le", "less_than_or_equals"]:
-        return "less_than_or_equals"
-    elif comparator in ["gt", "greater_than"]:
-        return "greater_than"
-    elif comparator in ["ge", "greater_than_or_equals"]:
-        return "greater_than_or_equals"
-    elif comparator in ["ne", "not_equals"]:
-        return "not_equals"
-    elif comparator in ["str_eq", "string_equals"]:
-        return "string_equals"
-    elif comparator in ["len_eq", "length_equals", "count_eq"]:
-        return "length_equals"
-    elif comparator in ["len_gt", "count_gt", "length_greater_than", "count_greater_than"]:
-        return "length_greater_than"
-    elif comparator in ["len_ge", "count_ge", "length_greater_than_or_equals",
-                        "count_greater_than_or_equals"]:
-        return "length_greater_than_or_equals"
-    elif comparator in ["len_lt", "count_lt", "length_less_than", "count_less_than"]:
-        return "length_less_than"
-    elif comparator in ["len_le", "count_le", "length_less_than_or_equals",
-                        "count_less_than_or_equals"]:
-        return "length_less_than_or_equals"
-    else:
-        return comparator
-
-
-def uniform_validator(validator):
-    """ unify validator
-
-    Args:
-        validator (dict): validator maybe in two formats:
-
-            format1: this is kept for compatiblity with the previous versions.
-                {"check": "status_code", "comparator": "eq", "expect": 201}
-                {"check": "$resp_body_success", "comparator": "eq", "expect": True}
-            format2: recommended new version, {comparator: [check_item, expected_value]}
-                {'eq': ['status_code', 201]}
-                {'eq': ['$resp_body_success', True]}
-
-    Returns
-        dict: validator info
-
-            {
-                "check": "status_code",
-                "expect": 201,
-                "comparator": "equals"
-            }
-
-    """
-    if not isinstance(validator, dict):
-        raise exceptions.ParamsError("invalid validator: {}".format(validator))
-
-    if "check" in validator and "expect" in validator:
-        # format1
-        check_item = validator["check"]
-        expect_value = validator["expect"]
-        comparator = validator.get("comparator", "eq")
-
-    elif len(validator) == 1:
-        # format2
-        comparator = list(validator.keys())[0]
-        compare_values = validator[comparator]
-
-        if not isinstance(compare_values, list) or len(compare_values) != 2:
-            raise exceptions.ParamsError("invalid validator: {}".format(validator))
-
-        check_item, expect_value = compare_values
-
-    else:
-        raise exceptions.ParamsError("invalid validator: {}".format(validator))
-
-    # uniform comparator, e.g. lt => less_than, eq => equals
-    comparator = get_uniform_comparator(comparator)
-
-    return {
-        "check": check_item,
-        "expect": expect_value,
-        "comparator": comparator
-    }
-
-
-def _convert_validators_to_mapping(validators):
-    """ convert validators list to mapping.
-
-    Args:
-        validators (list): validators in list
-
-    Returns:
-        dict: validators mapping, use (check, comparator) as key.
-
-    Examples:
-        >>> validators = [
-            {"check": "v1", "expect": 201, "comparator": "eq"},
-            {"check": {"b": 1}, "expect": 200, "comparator": "eq"}
-        ]
-        >>> print(_convert_validators_to_mapping(validators))
-        {
-            ("v1", "eq"): {"check": "v1", "expect": 201, "comparator": "eq"},
-            ('{"b": 1}', "eq"): {"check": {"b": 1}, "expect": 200, "comparator": "eq"}
+    def validate_script(self, script):
+        """ make validation with python script
+        """
+        validator_dict = {
+            "validate_script": "<br/>".join(script),
+            "check_result": "fail",
+            "exception": ""
         }
 
-    """
-    validators_mapping = {}
+        script = "\n    ".join(script)
+        code = """
+# encoding: utf-8
 
-    for validator in validators:
-        if not isinstance(validator["check"], collections.Hashable):
-            check = json.dumps(validator["check"])
-        else:
-            check = validator["check"]
+try:
+    {}
+except Exception as ex:
+    import traceback
+    import sys
+    _type, _value, _tb = sys.exc_info()
+    # filename, lineno, name, line
+    _, _lineno, _, line_content = traceback.extract_tb(_tb, 1)[0]
 
-        key = (check, validator["comparator"])
-        validators_mapping[key] = validator
+    line_no = _lineno - 4
 
-    return validators_mapping
-
-
-def extend_validators(raw_validators, override_validators):
-    """ extend raw_validators with override_validators.
-        override_validators will merge and override raw_validators.
-
-    Args:
-        raw_validators (dict):
-        override_validators (dict):
-
-    Returns:
-        list: extended validators
-
-    Examples:
-        >>> raw_validators = [{'eq': ['v1', 200]}, {"check": "s2", "expect": 16, "comparator": "len_eq"}]
-        >>> override_validators = [{"check": "v1", "expect": 201}, {'len_eq': ['s3', 12]}]
-        >>> extend_validators(raw_validators, override_validators)
-            [
-                {"check": "v1", "expect": 201, "comparator": "eq"},
-                {"check": "s2", "expect": 16, "comparator": "len_eq"},
-                {"check": "s3", "expect": 12, "comparator": "len_eq"}
-            ]
-
-    """
-
-    if not raw_validators:
-        return override_validators
-
-    elif not override_validators:
-        return raw_validators
+    c_exception = _type.__name__ + "\\n"
+    c_exception += "\\tError line number: " + str(line_no) + "\\n"
+    c_exception += "\\tError line content: " + str(line_content) + "\\n"
 
+    if _value.args:
+        c_exception += "\\tError description: " + str(_value)
     else:
-        def_validators_mapping = _convert_validators_to_mapping(raw_validators)
-        ref_validators_mapping = _convert_validators_to_mapping(override_validators)
+        c_exception += "\\tError description: " + _type.__name__
 
-        def_validators_mapping.update(ref_validators_mapping)
-        return list(def_validators_mapping.values())
+    raise _type(c_exception)
+""".format(script)
+        variables = {
+            "status_code": self.resp_obj.status_code,
+            "response_json": self.resp_obj.json,
+            "response": self.resp_obj
+        }
+        variables.update(self.session_context.test_variables_mapping)
 
+        try:
+            code = compile(code, '<string>', 'exec')
+            exec(code, variables)
+            validator_dict["check_result"] = "pass"
+            return validator_dict, ""
+        except Exception as ex:
+            validator_dict["check_result"] = "fail"
+            validator_dict["exception"] = "<br/>".join(str(ex).splitlines())
+            return validator_dict, str(ex)
 
-###############################################################################
-##   validate varibles and functions
-###############################################################################
+    def validate(self, validators):
+        """ make validation with comparators
+        """
+        self.validation_results = {}
+        if not validators:
+            return
 
+        logger.log_debug("start to validate.")
 
-def is_function(item):
-    """ Takes item object, returns True if it is a function.
-    """
-    return isinstance(item, types.FunctionType)
+        validate_pass = True
+        failures = []
 
+        for validator in validators:
 
-def is_variable(tup):
-    """ Takes (name, object) tuple, returns True if it is a variable.
-    """
-    name, item = tup
-    if callable(item):
-        # function or class
-        return False
+            if isinstance(validator, dict) and validator.get("type") == "python_script":
+                validator_dict, ex = self.validate_script(validator["script"])
+                if ex:
+                    validate_pass = False
+                    failures.append(ex)
 
-    if isinstance(item, types.ModuleType):
-        # imported module
-        return False
+                self.validation_results["validate_script"] = validator_dict
+                continue
 
-    if name.startswith("_"):
-        # private property
-        return False
+            if "validate_extractor" not in self.validation_results:
+                self.validation_results["validate_extractor"] = []
 
-    return True
+            # validator should be LazyFunction object
+            if not isinstance(validator, parser.LazyFunction):
+                raise exceptions.ValidationFailure(
+                    "validator should be parsed first: {}".format(validators))
 
+            # evaluate validator args with context variable mapping.
+            validator_args = validator.get_args()
+            check_item, expect_item = validator_args
+            check_value = self.__eval_validator_check(check_item)
+            expect_value = self.__eval_validator_expect(expect_item)
+            validator.update_args([check_value, expect_value])
 
-def validate_json_file(file_list):
-    """ validate JSON testcase format
-    """
-    for json_file in set(file_list):
-        if not json_file.endswith(".json"):
-            logger.log_warning("Only JSON file format can be validated, skip: {}".format(json_file))
-            continue
+            comparator = validator.func_name
+            validator_dict = {
+                "comparator": comparator,
+                "check": check_item,
+                "check_value": check_value,
+                "expect": expect_item,
+                "expect_value": expect_value
+            }
+            validate_msg = "\nvalidate: {} {} {}({})".format(
+                check_item,
+                comparator,
+                expect_value,
+                type(expect_value).__name__
+            )
 
-        logger.color_print("Start to validate JSON file: {}".format(json_file), "GREEN")
-
-        with io.open(json_file) as stream:
             try:
-                json.load(stream)
-            except ValueError as e:
-                raise SystemExit(e)
+                validator.to_value(self.session_context.test_variables_mapping)
+                validator_dict["check_result"] = "pass"
+                validate_msg += "\t==> pass"
+                logger.log_debug(validate_msg)
+            except (AssertionError, TypeError):
+                validate_pass = False
+                validator_dict["check_result"] = "fail"
+                validate_msg += "\t==> fail"
+                validate_msg += "\n{}({}) {} {}({})".format(
+                    check_value,
+                    type(check_value).__name__,
+                    comparator,
+                    expect_value,
+                    type(expect_value).__name__
+                )
+                logger.log_error(validate_msg)
+                failures.append(validate_msg)
 
-        print("OK")
+            self.validation_results["validate_extractor"].append(validator_dict)
+
+            # restore validator args, in case of running multiple times
+            validator.update_args(validator_args)
+
+        if not validate_pass:
+            failures_string = "\n".join([failure for failure in failures])
+            raise exceptions.ValidationFailure(failures_string)
diff --git a/pyproject.toml b/pyproject.toml
index 29385917..6b14c7d1 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "httprunner"
-version = "2.3.3"
+version = "2.4.0"
 description = "One-stop solution for HTTP(S) testing."
 license = "Apache-2.0"
 readme = "README.md"
diff --git a/tests/api_server.py b/tests/api_server.py
index d3a370d4..c7c73eee 100644
--- a/tests/api_server.py
+++ b/tests/api_server.py
@@ -5,7 +5,7 @@ from functools import wraps
 
 from flask import Flask, make_response, request
 
-from httprunner.built_in import gen_random_string
+from httprunner.builtin.functions import gen_random_string
 
 try:
     from httpbin import app as httpbin_app
diff --git a/tests/httpbin/validate.yml b/tests/httpbin/validate.yml
index 310b826b..0be60af8 100644
--- a/tests/httpbin/validate.yml
+++ b/tests/httpbin/validate.yml
@@ -1,13 +1,34 @@
 - config:
     name: basic test with httpbin
-    request:
-        base_url: http://httpbin.org/
+    base_url: http://httpbin.org/
 
 - test:
-    name: headers
+    name: validate response with json path
     request:
-        url: /headers
+        url: /get
+        params:
+            a: 1
+            b: 2
         method: GET
     validate:
         - eq: ["status_code", 200]
-        - assert_status_code_is_200: ["status_code"]
+        - eq: ["json.args.a", '1']
+        - eq: ["json.args.b", '2']
+    validate_script:
+        - "assert status_code == 200"
+
+
+- test:
+    name: validate response with python script
+    request:
+        url: /get
+        params:
+            a: 1
+            b: 2
+        method: GET
+    validate:
+        - eq: ["status_code", 200]
+    validate_script:
+        - "assert status_code == 201"
+        - "a = response_json.get('args').get('a')"
+        - "assert a == '1'"
diff --git a/tests/test_api.py b/tests/test_api.py
index d4f2e125..cca20309 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -289,6 +289,10 @@ class TestHttpRunner(ApiServerUnittest):
         self.assertEqual(summary["stat"]["testcases"]["total"], 2)
         self.assertEqual(summary["stat"]["teststeps"]["total"], 4)
 
+    def test_validate_script(self):
+        summary = self.runner.run("tests/httpbin/validate.yml")
+        self.assertFalse(summary["success"])
+
     def test_run_httprunner_with_hooks(self):
         testcase_file_path = os.path.join(
             os.getcwd(), 'tests/httpbin/hooks.yml')
@@ -327,9 +331,9 @@ class TestHttpRunner(ApiServerUnittest):
                 ]
             }
         ]
-        loader.load_project_tests("tests")
+
         tests_mapping = {
-            "project_mapping": loader.project_mapping,
+            "project_mapping": loader.load_project_data("tests"),
             "testcases": testcases
         }
         summary = self.runner.run_tests(tests_mapping)
@@ -359,9 +363,8 @@ class TestHttpRunner(ApiServerUnittest):
                 ]
             }
         ]
-        loader.load_project_tests("tests")
         tests_mapping = {
-            "project_mapping": loader.project_mapping,
+            "project_mapping": loader.load_project_data("tests"),
             "testcases": testcases
         }
         summary = self.runner.run_tests(tests_mapping)
@@ -389,9 +392,8 @@ class TestHttpRunner(ApiServerUnittest):
                 ]
             }
         ]
-        loader.load_project_tests("tests")
         tests_mapping = {
-            "project_mapping": loader.project_mapping,
+            "project_mapping": loader.load_project_data("tests"),
             "testcases": testcases
         }
         summary = self.runner.run_tests(tests_mapping)
@@ -600,7 +602,7 @@ class TestApi(ApiServerUnittest):
 
     def test_testcase_loader(self):
         testcase_path = "tests/testcases/setup.yml"
-        tests_mapping = loader.load_tests(testcase_path)
+        tests_mapping = loader.load_cases(testcase_path)
 
         project_mapping = tests_mapping["project_mapping"]
         self.assertIsInstance(project_mapping, dict)
@@ -625,7 +627,7 @@ class TestApi(ApiServerUnittest):
 
     def test_testcase_parser(self):
         testcase_path = "tests/testcases/setup.yml"
-        tests_mapping = loader.load_tests(testcase_path)
+        tests_mapping = loader.load_cases(testcase_path)
 
         parsed_testcases = parser.parse_tests(tests_mapping)
 
@@ -646,7 +648,7 @@ class TestApi(ApiServerUnittest):
 
     def test_testcase_add_tests(self):
         testcase_path = "tests/testcases/setup.yml"
-        tests_mapping = loader.load_tests(testcase_path)
+        tests_mapping = loader.load_cases(testcase_path)
 
         testcases = parser.parse_tests(tests_mapping)
         runner = HttpRunner()
@@ -660,7 +662,7 @@ class TestApi(ApiServerUnittest):
 
     def test_testcase_complex_verify(self):
         testcase_path = "tests/testcases/create_user.yml"
-        tests_mapping = loader.load_tests(testcase_path)
+        tests_mapping = loader.load_cases(testcase_path)
         testcases = parser.parse_tests(tests_mapping)
         teststeps = testcases[0]["teststeps"]
 
@@ -677,7 +679,7 @@ class TestApi(ApiServerUnittest):
 
     def test_testcase_simple_run_suite(self):
         testcase_path = "tests/testcases/setup.yml"
-        tests_mapping = loader.load_tests(testcase_path)
+        tests_mapping = loader.load_cases(testcase_path)
         testcases = parser.parse_tests(tests_mapping)
         runner = HttpRunner()
         test_suite = runner._add_tests(testcases)
@@ -691,7 +693,7 @@ class TestApi(ApiServerUnittest):
             "tests/testcases/create_user.json",
             "tests/testcases/create_user.v2.json"
         ]:
-            tests_mapping = loader.load_tests(testcase_path)
+            tests_mapping = loader.load_cases(testcase_path)
             testcases = parser.parse_tests(tests_mapping)
             runner = HttpRunner()
             test_suite = runner._add_tests(testcases)
@@ -710,7 +712,7 @@ class TestApi(ApiServerUnittest):
 
     def test_testsuite_loader(self):
         testcase_path = "tests/testsuites/create_users.yml"
-        tests_mapping = loader.load_tests(testcase_path)
+        tests_mapping = loader.load_cases(testcase_path)
 
         project_mapping = tests_mapping["project_mapping"]
         self.assertIsInstance(project_mapping, dict)
@@ -742,7 +744,7 @@ class TestApi(ApiServerUnittest):
 
     def test_testsuite_parser(self):
         testcase_path = "tests/testsuites/create_users.yml"
-        tests_mapping = loader.load_tests(testcase_path)
+        tests_mapping = loader.load_cases(testcase_path)
 
         parsed_testcases = parser.parse_tests(tests_mapping)
         self.assertEqual(len(parsed_testcases), 2)
@@ -760,7 +762,7 @@ class TestApi(ApiServerUnittest):
 
     def test_testsuite_add_tests(self):
         testcase_path = "tests/testsuites/create_users.yml"
-        tests_mapping = loader.load_tests(testcase_path)
+        tests_mapping = loader.load_cases(testcase_path)
 
         testcases = parser.parse_tests(tests_mapping)
         runner = HttpRunner()
@@ -772,7 +774,7 @@ class TestApi(ApiServerUnittest):
 
     def test_testsuite_run_suite(self):
         testcase_path = "tests/testsuites/create_users.yml"
-        tests_mapping = loader.load_tests(testcase_path)
+        tests_mapping = loader.load_cases(testcase_path)
 
         testcases = parser.parse_tests(tests_mapping)
 
diff --git a/tests/test_context.py b/tests/test_context.py
index 67367c97..46bbf343 100644
--- a/tests/test_context.py
+++ b/tests/test_context.py
@@ -8,8 +8,7 @@ from tests.base import ApiServerUnittest, gen_random_string
 class TestContext(ApiServerUnittest):
 
     def setUp(self):
-        loader.load_project_tests(os.path.join(os.getcwd(), "tests"))
-        project_mapping = loader.project_mapping
+        loader.load_project_data(os.path.join(os.getcwd(), "tests"))
         self.context = context.SessionContext(
             variables={"SECRET_KEY": "DebugTalk"}
         )
diff --git a/tests/test_loader/__init__.py b/tests/test_loader/__init__.py
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/test_loader.py b/tests/test_loader/test_cases.py
similarity index 51%
rename from tests/test_loader.py
rename to tests/test_loader/test_cases.py
index 21268074..7bea02a6 100644
--- a/tests/test_loader.py
+++ b/tests/test_loader/test_cases.py
@@ -3,207 +3,21 @@ import os
 import unittest
 
 from httprunner import exceptions, loader
-
-
-class TestFileLoader(unittest.TestCase):
-
-    def test_load_yaml_file_file_format_error(self):
-        yaml_tmp_file = "tests/data/tmp.yml"
-        # create empty yaml file
-        with open(yaml_tmp_file, 'w') as f:
-            f.write("")
-
-        with self.assertRaises(exceptions.FileFormatError):
-            loader.load_yaml_file(yaml_tmp_file)
-
-        os.remove(yaml_tmp_file)
-
-        # create invalid format yaml file
-        with open(yaml_tmp_file, 'w') as f:
-            f.write("abc")
-
-        with self.assertRaises(exceptions.FileFormatError):
-            loader.load_yaml_file(yaml_tmp_file)
-
-        os.remove(yaml_tmp_file)
-
-    def test_load_json_file_file_format_error(self):
-        json_tmp_file = "tests/data/tmp.json"
-        # create empty file
-        with open(json_tmp_file, 'w') as f:
-            f.write("")
-
-        with self.assertRaises(exceptions.FileFormatError):
-            loader.load_json_file(json_tmp_file)
-
-        os.remove(json_tmp_file)
-
-        # create empty json file
-        with open(json_tmp_file, 'w') as f:
-            f.write("{}")
-
-        with self.assertRaises(exceptions.FileFormatError):
-            loader.load_json_file(json_tmp_file)
-
-        os.remove(json_tmp_file)
-
-        # create invalid format json file
-        with open(json_tmp_file, 'w') as f:
-            f.write("abc")
-
-        with self.assertRaises(exceptions.FileFormatError):
-            loader.load_json_file(json_tmp_file)
-
-        os.remove(json_tmp_file)
-
-    def test_load_testcases_bad_filepath(self):
-        testcase_file_path = os.path.join(os.getcwd(), 'tests/data/demo')
-        with self.assertRaises(exceptions.FileNotFound):
-            loader.load_file(testcase_file_path)
-
-    def test_load_json_testcases(self):
-        testcase_file_path = os.path.join(
-            os.getcwd(), 'tests/data/demo_testcase_hardcode.json')
-        testcases = loader.load_file(testcase_file_path)
-        self.assertEqual(len(testcases), 3)
-        test = testcases[0]["test"]
-        self.assertIn('name', test)
-        self.assertIn('request', test)
-        self.assertIn('url', test['request'])
-        self.assertIn('method', test['request'])
-
-    def test_load_yaml_testcases(self):
-        testcase_file_path = os.path.join(
-            os.getcwd(), 'tests/data/demo_testcase_hardcode.yml')
-        testcases = loader.load_file(testcase_file_path)
-        self.assertEqual(len(testcases), 3)
-        test = testcases[0]["test"]
-        self.assertIn('name', test)
-        self.assertIn('request', test)
-        self.assertIn('url', test['request'])
-        self.assertIn('method', test['request'])
-
-    def test_load_csv_file_one_parameter(self):
-        csv_file_path = os.path.join(
-            os.getcwd(), 'tests/data/user_agent.csv')
-        csv_content = loader.load_file(csv_file_path)
-        self.assertEqual(
-            csv_content,
-            [
-                {'user_agent': 'iOS/10.1'},
-                {'user_agent': 'iOS/10.2'},
-                {'user_agent': 'iOS/10.3'}
-            ]
-        )
-
-    def test_load_csv_file_multiple_parameters(self):
-        csv_file_path = os.path.join(
-            os.getcwd(), 'tests/data/account.csv')
-        csv_content = loader.load_file(csv_file_path)
-        self.assertEqual(
-            csv_content,
-            [
-                {'username': 'test1', 'password': '111111'},
-                {'username': 'test2', 'password': '222222'},
-                {'username': 'test3', 'password': '333333'}
-            ]
-        )
-
-    def test_load_folder_files(self):
-        folder = os.path.join(os.getcwd(), 'tests')
-        file1 = os.path.join(os.getcwd(), 'tests', 'test_utils.py')
-        file2 = os.path.join(os.getcwd(), 'tests', 'api', 'reset_all.yml')
-
-        files = loader.load_folder_files(folder, recursive=False)
-        self.assertEqual(files, [])
-
-        files = loader.load_folder_files(folder)
-        self.assertIn(file2, files)
-        self.assertNotIn(file1, files)
-
-        files = loader.load_folder_files("not_existed_foulder", recursive=False)
-        self.assertEqual([], files)
-
-        files = loader.load_folder_files(file2, recursive=False)
-        self.assertEqual([], files)
-
-    def test_load_dot_env_file(self):
-        dot_env_path = os.path.join(
-            os.getcwd(), "tests", ".env"
-        )
-        env_variables_mapping = loader.load_dot_env_file(dot_env_path)
-        self.assertIn("PROJECT_KEY", env_variables_mapping)
-        self.assertEqual(env_variables_mapping["UserName"], "debugtalk")
-
-    def test_load_custom_dot_env_file(self):
-        dot_env_path = os.path.join(
-            os.getcwd(), "tests", "data", "test.env"
-        )
-        env_variables_mapping = loader.load_dot_env_file(dot_env_path)
-        self.assertIn("PROJECT_KEY", env_variables_mapping)
-        self.assertEqual(env_variables_mapping["UserName"], "test")
-        self.assertEqual(env_variables_mapping["content_type"], "application/json; charset=UTF-8")
-
-    def test_load_env_path_not_exist(self):
-        dot_env_path = os.path.join(
-            os.getcwd(), "tests", "data",
-        )
-        env_variables_mapping = loader.load_dot_env_file(dot_env_path)
-        self.assertEqual(env_variables_mapping, {})
-
-    def test_locate_file(self):
-        with self.assertRaises(exceptions.FileNotFound):
-            loader.locate_file(os.getcwd(), "debugtalk.py")
-
-        with self.assertRaises(exceptions.FileNotFound):
-            loader.locate_file("", "debugtalk.py")
-
-        start_path = os.path.join(os.getcwd(), "tests")
-        self.assertEqual(
-            loader.locate_file(start_path, "debugtalk.py"),
-            os.path.join(
-                os.getcwd(), "tests/debugtalk.py"
-            )
-        )
-        self.assertEqual(
-            loader.locate_file("tests/", "debugtalk.py"),
-            os.path.join(os.getcwd(), "tests", "debugtalk.py")
-        )
-        self.assertEqual(
-            loader.locate_file("tests", "debugtalk.py"),
-            os.path.join(os.getcwd(), "tests", "debugtalk.py")
-        )
-        self.assertEqual(
-            loader.locate_file("tests/base.py", "debugtalk.py"),
-            os.path.join(os.getcwd(), "tests", "debugtalk.py")
-        )
-        self.assertEqual(
-            loader.locate_file("tests/data/demo_testcase.yml", "debugtalk.py"),
-            os.path.join(os.getcwd(), "tests", "debugtalk.py")
-        )
-
-    def test_load_folder_content(self):
-        path = os.path.join(os.getcwd(), "tests", "api")
-        items_mapping = loader.load_folder_content(path)
-        file_path = os.path.join(os.getcwd(), "tests", "api", "reset_all.yml")
-        self.assertIn(file_path, items_mapping)
-        self.assertIsInstance(items_mapping[file_path], dict)
+from httprunner.loader import buildup
 
 
 class TestModuleLoader(unittest.TestCase):
 
     def test_filter_module_functions(self):
-        module_functions = loader.load_module_functions(loader)
+        module_functions = buildup.load_module_functions(buildup)
         self.assertIn("load_module_functions", module_functions)
         self.assertNotIn("is_py3", module_functions)
 
     def test_load_debugtalk_module(self):
-        loader.load_project_tests(os.path.join(os.getcwd(), "httprunner"))
-        project_mapping = loader.project_mapping
+        project_mapping = buildup.load_project_data(os.path.join(os.getcwd(), "httprunner"))
         self.assertNotIn("alter_response", project_mapping["functions"])
 
-        loader.load_project_tests(os.path.join(os.getcwd(), "tests"))
-        project_mapping = loader.project_mapping
+        project_mapping = buildup.load_project_data(os.path.join(os.getcwd(), "tests"))
         self.assertIn("alter_response", project_mapping["functions"])
 
         is_status_code_200 = project_mapping["functions"]["is_status_code_200"]
@@ -211,27 +25,27 @@ class TestModuleLoader(unittest.TestCase):
         self.assertFalse(is_status_code_200(500))
 
     def test_load_debugtalk_py(self):
-        loader.load_project_tests("tests/data/demo_testcase.yml")
-        project_working_directory = loader.project_mapping["PWD"]
-        debugtalk_functions = loader.project_mapping["functions"]
+        project_mapping = buildup.load_project_data("tests/data/demo_testcase.yml")
+        project_working_directory = project_mapping["PWD"]
+        debugtalk_functions = project_mapping["functions"]
         self.assertEqual(
             project_working_directory,
             os.path.join(os.getcwd(), "tests")
         )
         self.assertIn("gen_md5", debugtalk_functions)
 
-        loader.load_project_tests("tests/base.py")
-        project_working_directory = loader.project_mapping["PWD"]
-        debugtalk_functions = loader.project_mapping["functions"]
+        project_mapping = buildup.load_project_data("tests/base.py")
+        project_working_directory = project_mapping["PWD"]
+        debugtalk_functions = project_mapping["functions"]
         self.assertEqual(
             project_working_directory,
             os.path.join(os.getcwd(), "tests")
         )
         self.assertIn("gen_md5", debugtalk_functions)
 
-        loader.load_project_tests("httprunner/__init__.py")
-        project_working_directory = loader.project_mapping["PWD"]
-        debugtalk_functions = loader.project_mapping["functions"]
+        project_mapping = buildup.load_project_data("httprunner/__init__.py")
+        project_working_directory = project_mapping["PWD"]
+        debugtalk_functions = project_mapping["functions"]
         self.assertEqual(
             project_working_directory,
             os.getcwd()
@@ -243,9 +57,8 @@ class TestSuiteLoader(unittest.TestCase):
 
     @classmethod
     def setUpClass(cls):
-        loader.load_project_tests(os.path.join(os.getcwd(), "tests"))
-        cls.project_mapping = loader.project_mapping
-        cls.tests_def_mapping = loader.tests_def_mapping
+        cls.project_mapping = buildup.load_project_data(os.path.join(os.getcwd(), "tests"))
+        cls.tests_def_mapping = buildup.tests_def_mapping
 
     def test_load_teststep_api(self):
         raw_test = {
@@ -255,7 +68,7 @@ class TestSuiteLoader(unittest.TestCase):
                 {"uid": "999"}
             ]
         }
-        teststep = loader.load_teststep(raw_test)
+        teststep = buildup.load_teststep(raw_test)
         self.assertEqual(
             "create user (override).",
             teststep["name"]
@@ -273,7 +86,7 @@ class TestSuiteLoader(unittest.TestCase):
                 {"device_sn": "$device_sn"}
             ]
         }
-        testcase = loader.load_teststep(raw_test)
+        testcase = buildup.load_teststep(raw_test)
         self.assertEqual(
             "setup and reset all (override).",
             testcase["name"]
@@ -284,7 +97,7 @@ class TestSuiteLoader(unittest.TestCase):
         self.assertEqual(tests[1]["name"], "reset all users")
 
     def test_load_test_file_api(self):
-        loaded_content = loader.load_test_file("tests/api/create_user.yml")
+        loaded_content = buildup.load_test_file("tests/api/create_user.yml")
         self.assertEqual(loaded_content["type"], "api")
         self.assertIn("path", loaded_content)
         self.assertIn("request", loaded_content)
@@ -292,8 +105,8 @@ class TestSuiteLoader(unittest.TestCase):
 
     def test_load_test_file_testcase(self):
         for loaded_content in [
-            loader.load_test_file("tests/testcases/setup.yml"),
-            loader.load_test_file("tests/testcases/setup.json")
+            buildup.load_test_file("tests/testcases/setup.yml"),
+            buildup.load_test_file("tests/testcases/setup.json")
         ]:
             self.assertEqual(loaded_content["type"], "testcase")
             self.assertIn("path", loaded_content)
@@ -304,8 +117,8 @@ class TestSuiteLoader(unittest.TestCase):
 
     def test_load_test_file_testcase_v2(self):
         for loaded_content in [
-            loader.load_test_file("tests/testcases/setup.v2.yml"),
-            loader.load_test_file("tests/testcases/setup.v2.json")
+            buildup.load_test_file("tests/testcases/setup.v2.yml"),
+            buildup.load_test_file("tests/testcases/setup.v2.json")
         ]:
             self.assertEqual(loaded_content["type"], "testcase")
             self.assertIn("path", loaded_content)
@@ -316,8 +129,8 @@ class TestSuiteLoader(unittest.TestCase):
 
     def test_load_test_file_testsuite(self):
         for loaded_content in [
-            loader.load_test_file("tests/testsuites/create_users.yml"),
-            loader.load_test_file("tests/testsuites/create_users.json")
+            buildup.load_test_file("tests/testsuites/create_users.yml"),
+            buildup.load_test_file("tests/testsuites/create_users.json")
         ]:
             self.assertEqual(loaded_content["type"], "testsuite")
 
@@ -332,8 +145,8 @@ class TestSuiteLoader(unittest.TestCase):
 
     def test_load_test_file_testsuite_v2(self):
         for loaded_content in [
-            loader.load_test_file("tests/testsuites/create_users.v2.yml"),
-            loader.load_test_file("tests/testsuites/create_users.v2.json")
+            buildup.load_test_file("tests/testsuites/create_users.v2.yml"),
+            buildup.load_test_file("tests/testsuites/create_users.v2.json")
         ]:
             self.assertEqual(loaded_content["type"], "testsuite")
 
@@ -349,7 +162,7 @@ class TestSuiteLoader(unittest.TestCase):
     def test_load_tests_api_file(self):
         path = os.path.join(
             os.getcwd(), 'tests/api/create_user.yml')
-        tests_mapping = loader.load_tests(path)
+        tests_mapping = loader.load_cases(path)
         project_mapping = tests_mapping["project_mapping"]
         api_list = tests_mapping["apis"]
         self.assertEqual(len(api_list), 1)
@@ -359,7 +172,7 @@ class TestSuiteLoader(unittest.TestCase):
         # absolute file path
         path = os.path.join(
             os.getcwd(), 'tests/data/demo_testcase_hardcode.json')
-        tests_mapping = loader.load_tests(path)
+        tests_mapping = loader.load_cases(path)
         project_mapping = tests_mapping["project_mapping"]
         testcases_list = tests_mapping["testcases"]
         self.assertEqual(len(testcases_list), 1)
@@ -368,7 +181,7 @@ class TestSuiteLoader(unittest.TestCase):
 
         # relative file path
         path = 'tests/data/demo_testcase_hardcode.yml'
-        tests_mapping = loader.load_tests(path)
+        tests_mapping = loader.load_cases(path)
         project_mapping = tests_mapping["project_mapping"]
         testcases_list = tests_mapping["testcases"]
         self.assertEqual(len(testcases_list), 1)
@@ -378,7 +191,7 @@ class TestSuiteLoader(unittest.TestCase):
     def test_load_tests_testcase_file_2(self):
         testcase_file_path = os.path.join(
             os.getcwd(), 'tests/data/demo_testcase.yml')
-        tests_mapping = loader.load_tests(testcase_file_path)
+        tests_mapping = loader.load_cases(testcase_file_path)
         testcases = tests_mapping["testcases"]
         self.assertIsInstance(testcases, list)
         self.assertEqual(testcases[0]["config"]["name"], '123t$var_a')
@@ -398,7 +211,7 @@ class TestSuiteLoader(unittest.TestCase):
     def test_load_tests_testcase_file_with_api_ref(self):
         path = os.path.join(
             os.getcwd(), 'tests/data/demo_testcase_layer.yml')
-        tests_mapping = loader.load_tests(path)
+        tests_mapping = loader.load_cases(path)
         project_mapping = tests_mapping["project_mapping"]
         testcases_list = tests_mapping["testcases"]
         self.assertIn('device_sn', testcases_list[0]["config"]["variables"])
@@ -418,7 +231,7 @@ class TestSuiteLoader(unittest.TestCase):
     def test_load_tests_testsuite_file_with_testcase_ref(self):
         path = os.path.join(
             os.getcwd(), 'tests/testsuites/create_users.yml')
-        tests_mapping = loader.load_tests(path)
+        tests_mapping = loader.load_cases(path)
         project_mapping = tests_mapping["project_mapping"]
         testsuites_list = tests_mapping["testsuites"]
 
@@ -443,13 +256,13 @@ class TestSuiteLoader(unittest.TestCase):
     def test_load_tests_folder_path(self):
         # absolute folder path
         path = os.path.join(os.getcwd(), 'tests/data')
-        tests_mapping = loader.load_tests(path)
+        tests_mapping = loader.load_cases(path)
         testcase_list_1 = tests_mapping["testcases"]
         self.assertGreater(len(testcase_list_1), 4)
 
         # relative folder path
         path = 'tests/data/'
-        tests_mapping = loader.load_tests(path)
+        tests_mapping = loader.load_cases(path)
         testcase_list_2 = tests_mapping["testcases"]
         self.assertEqual(len(testcase_list_1), len(testcase_list_2))
 
@@ -457,22 +270,22 @@ class TestSuiteLoader(unittest.TestCase):
         # absolute folder path
         path = os.path.join(os.getcwd(), 'tests/data_not_exist')
         with self.assertRaises(exceptions.FileNotFound):
-            loader.load_tests(path)
+            loader.load_cases(path)
 
         # relative folder path
         path = 'tests/data_not_exist'
         with self.assertRaises(exceptions.FileNotFound):
-            loader.load_tests(path)
+            loader.load_cases(path)
 
     def test_load_api_folder(self):
         path = os.path.join(os.getcwd(), "tests", "api")
-        api_definition_mapping = loader.load_api_folder(path)
+        api_definition_mapping = buildup.load_api_folder(path)
         api_file_path = os.path.join(os.getcwd(), "tests", "api", "get_token.yml")
         self.assertIn(api_file_path, api_definition_mapping)
         self.assertIn("request", api_definition_mapping[api_file_path])
 
     def test_load_project_tests(self):
-        loader.load_project_tests(os.path.join(os.getcwd(), "tests"))
+        buildup.load_project_data(os.path.join(os.getcwd(), "tests"))
         api_file_path = os.path.join(os.getcwd(), "tests", "api", "get_token.yml")
         self.assertIn(api_file_path, self.tests_def_mapping["api"])
         self.assertEqual(self.project_mapping["env"]["PROJECT_KEY"], "ABCDEFGH")
diff --git a/tests/test_loader/test_check.py b/tests/test_loader/test_check.py
new file mode 100644
index 00000000..5ba16571
--- /dev/null
+++ b/tests/test_loader/test_check.py
@@ -0,0 +1,76 @@
+import unittest
+
+from httprunner.loader import check
+
+
+class TestLoaderCheck(unittest.TestCase):
+
+    def test_is_function(self):
+        func = lambda x: x + 1
+        self.assertTrue(check.is_function(func))
+        self.assertTrue(check.is_function(check.is_testcase))
+
+    def test_is_testcases(self):
+        data_structure = "path/to/file"
+        self.assertFalse(check.is_testcases(data_structure))
+        data_structure = ["path/to/file1", "path/to/file2"]
+        self.assertFalse(check.is_testcases(data_structure))
+
+        data_structure = {
+            "project_mapping": {
+                "PWD": "XXXXX",
+                "functions": {},
+                "env": {}
+            },
+            "testcases": [
+                {  # testcase data structure
+                    "config": {
+                        "name": "desc1",
+                        "path": "testcase1_path",
+                        "variables": [],  # optional
+                    },
+                    "teststeps": [
+                        # test data structure
+                        {
+                            'name': 'test step desc1',
+                            'variables': [],  # optional
+                            'extract': [],  # optional
+                            'validate': [],
+                            'request': {}
+                        },
+                        # test_dict2   # another test dict
+                    ]
+                },
+                # testcase_dict_2     # another testcase dict
+            ]
+        }
+        self.assertTrue(check.is_testcases(data_structure))
+        data_structure = [
+            {
+                "name": "desc1",
+                "config": {},
+                "api": {},
+                "testcases": ["testcase11", "testcase12"]
+            },
+            {
+                "name": "desc2",
+                "config": {},
+                "api": {},
+                "testcases": ["testcase21", "testcase22"]
+            }
+        ]
+        self.assertTrue(data_structure)
+
+    def test_is_variable(self):
+        var1 = 123
+        var2 = "abc"
+        self.assertTrue(check.is_variable(("var1", var1)))
+        self.assertTrue(check.is_variable(("var2", var2)))
+
+        __var = 123
+        self.assertFalse(check.is_variable(("__var", __var)))
+
+        func = lambda x: x + 1
+        self.assertFalse(check.is_variable(("func", func)))
+
+        self.assertFalse(check.is_variable(("unittest", unittest)))
diff --git a/tests/test_loader/test_load.py b/tests/test_loader/test_load.py
new file mode 100644
index 00000000..a98493f7
--- /dev/null
+++ b/tests/test_loader/test_load.py
@@ -0,0 +1,159 @@
+import os
+import unittest
+
+from httprunner import exceptions
+from httprunner.loader import load
+
+
+class TestFileLoader(unittest.TestCase):
+
+    def test_load_yaml_file_file_format_error(self):
+        yaml_tmp_file = "tests/data/tmp.yml"
+        # create empty yaml file
+        with open(yaml_tmp_file, 'w') as f:
+            f.write("")
+
+        with self.assertRaises(exceptions.FileFormatError):
+            load._load_yaml_file(yaml_tmp_file)
+
+        os.remove(yaml_tmp_file)
+
+        # create invalid format yaml file
+        with open(yaml_tmp_file, 'w') as f:
+            f.write("abc")
+
+        with self.assertRaises(exceptions.FileFormatError):
+            load._load_yaml_file(yaml_tmp_file)
+
+        os.remove(yaml_tmp_file)
+
+    def test_load_json_file_file_format_error(self):
+        json_tmp_file = "tests/data/tmp.json"
+        # create empty file
+        with open(json_tmp_file, 'w') as f:
+            f.write("")
+
+        with self.assertRaises(exceptions.FileFormatError):
+            load._load_json_file(json_tmp_file)
+
+        os.remove(json_tmp_file)
+
+        # create empty json file
+        with open(json_tmp_file, 'w') as f:
+            f.write("{}")
+
+        with self.assertRaises(exceptions.FileFormatError):
+            load._load_json_file(json_tmp_file)
+
+        os.remove(json_tmp_file)
+
+        # create invalid format json file
+        with open(json_tmp_file, 'w') as f:
+            f.write("abc")
+
+        with self.assertRaises(exceptions.FileFormatError):
+            load._load_json_file(json_tmp_file)
+
+        os.remove(json_tmp_file)
+
+    def test_load_testcases_bad_filepath(self):
+        testcase_file_path = os.path.join(os.getcwd(), 'tests/data/demo')
+        with self.assertRaises(exceptions.FileNotFound):
+            load.load_file(testcase_file_path)
+
+    def test_load_json_testcases(self):
+        testcase_file_path = os.path.join(
+            os.getcwd(), 'tests/data/demo_testcase_hardcode.json')
+        testcases = load.load_file(testcase_file_path)
+        self.assertEqual(len(testcases), 3)
+        test = testcases[0]["test"]
+        self.assertIn('name', test)
+        self.assertIn('request', test)
+        self.assertIn('url', test['request'])
+        self.assertIn('method', test['request'])
+
+    def test_load_yaml_testcases(self):
+        testcase_file_path = os.path.join(
+            os.getcwd(), 'tests/data/demo_testcase_hardcode.yml')
+        testcases = load.load_file(testcase_file_path)
+        self.assertEqual(len(testcases), 3)
+        test = testcases[0]["test"]
+        self.assertIn('name', test)
+        self.assertIn('request', test)
+        self.assertIn('url', test['request'])
+        self.assertIn('method', test['request'])
+
+    def test_load_csv_file_one_parameter(self):
+        csv_file_path = os.path.join(
+            os.getcwd(), 'tests/data/user_agent.csv')
+        csv_content = load.load_file(csv_file_path)
+        self.assertEqual(
+            csv_content,
+            [
+                {'user_agent': 'iOS/10.1'},
+                {'user_agent': 'iOS/10.2'},
+                {'user_agent': 'iOS/10.3'}
+            ]
+        )
+
+    def test_load_csv_file_multiple_parameters(self):
+        csv_file_path = os.path.join(
+            os.getcwd(), 'tests/data/account.csv')
+        csv_content = load.load_file(csv_file_path)
+        self.assertEqual(
+            csv_content,
+            [
+                {'username': 'test1', 'password': '111111'},
+                {'username': 'test2', 'password': '222222'},
+                {'username': 'test3', 'password': '333333'}
+            ]
+        )
+
+    def test_load_folder_files(self):
+        folder = os.path.join(os.getcwd(), 'tests')
+        file1 = os.path.join(os.getcwd(), 'tests', 'test_utils.py')
+        file2 = os.path.join(os.getcwd(), 'tests', 'api', 'reset_all.yml')
+
+        files = load.load_folder_files(folder, recursive=False)
+        self.assertEqual(files, [])
+
+        files = load.load_folder_files(folder)
+        self.assertIn(file2, files)
+        self.assertNotIn(file1, files)
+
+        files = load.load_folder_files("not_existed_foulder", recursive=False)
+        self.assertEqual([], files)
+
+        files = load.load_folder_files(file2, recursive=False)
+        self.assertEqual([], files)
+
+    def test_load_dot_env_file(self):
+        dot_env_path = os.path.join(
+            os.getcwd(), "tests", ".env"
+        )
+        env_variables_mapping = load.load_dot_env_file(dot_env_path)
+        self.assertIn("PROJECT_KEY", env_variables_mapping)
+        self.assertEqual(env_variables_mapping["UserName"], "debugtalk")
+
+    def test_load_custom_dot_env_file(self):
+        dot_env_path = os.path.join(
+            os.getcwd(), "tests", "data", "test.env"
+        )
+        env_variables_mapping = load.load_dot_env_file(dot_env_path)
+        self.assertIn("PROJECT_KEY", env_variables_mapping)
+        self.assertEqual(env_variables_mapping["UserName"], "test")
+        self.assertEqual(env_variables_mapping["content_type"], "application/json; charset=UTF-8")
+
+    def test_load_env_path_not_exist(self):
+        dot_env_path = os.path.join(
+            os.getcwd(), "tests", "data",
+        )
+        env_variables_mapping = load.load_dot_env_file(dot_env_path)
+        self.assertEqual(env_variables_mapping, {})
+
+    def test_load_folder_content(self):
+        path = os.path.join(os.getcwd(), "tests", "api")
+        items_mapping = load.load_folder_content(path)
+        file_path = os.path.join(os.getcwd(), "tests", "api", "reset_all.yml")
+        self.assertIn(file_path, items_mapping)
+        self.assertIsInstance(items_mapping[file_path], dict)
diff --git a/tests/test_loader/test_locate.py b/tests/test_loader/test_locate.py
new file mode 100644
index 00000000..54a2d15c
--- /dev/null
+++ b/tests/test_loader/test_locate.py
@@ -0,0 +1,40 @@
+
+import os
+import unittest
+
+from httprunner import exceptions
+from httprunner.loader import locate
+
+
+class TestLoaderLocate(unittest.TestCase):
+
+    def test_locate_file(self):
+        with self.assertRaises(exceptions.FileNotFound):
+            locate.locate_file(os.getcwd(), "debugtalk.py")
+
+        with self.assertRaises(exceptions.FileNotFound):
+            locate.locate_file("", "debugtalk.py")
+
+        start_path = os.path.join(os.getcwd(), "tests")
+        self.assertEqual(
+            locate.locate_file(start_path, "debugtalk.py"),
+            os.path.join(
+                os.getcwd(), "tests/debugtalk.py"
+            )
+        )
+        self.assertEqual(
+            locate.locate_file("tests/", "debugtalk.py"),
+            os.path.join(os.getcwd(), "tests", "debugtalk.py")
+        )
+        self.assertEqual(
+            locate.locate_file("tests", "debugtalk.py"),
+            os.path.join(os.getcwd(), "tests", "debugtalk.py")
+        )
+        self.assertEqual(
+            locate.locate_file("tests/base.py", "debugtalk.py"),
+            os.path.join(os.getcwd(), "tests", "debugtalk.py")
+        )
+        self.assertEqual(
+            locate.locate_file("tests/data/demo_testcase.yml", "debugtalk.py"),
+            os.path.join(os.getcwd(), "tests", "debugtalk.py")
+        )
diff --git a/tests/test_parser.py b/tests/test_parser.py
index 6f76148e..fa9b248b 100644
--- a/tests/test_parser.py
+++ b/tests/test_parser.py
@@ -3,6 +3,7 @@ import time
 import unittest
 
 from httprunner import exceptions, loader, parser
+from httprunner.loader import load
 from tests.debugtalk import gen_random_string, sum_two
 
 
@@ -806,6 +807,104 @@ class TestParserBasic(unittest.TestCase):
         self.assertEqual(parsed_variables["var2"], "abc$123")
         self.assertEqual(parsed_variables["var3"], "abc$$num0")
 
+    def test_get_uniform_comparator(self):
+        self.assertEqual(parser.get_uniform_comparator("eq"), "equals")
+        self.assertEqual(parser.get_uniform_comparator("=="), "equals")
+        self.assertEqual(parser.get_uniform_comparator("lt"), "less_than")
+        self.assertEqual(parser.get_uniform_comparator("le"), "less_than_or_equals")
+        self.assertEqual(parser.get_uniform_comparator("gt"), "greater_than")
+        self.assertEqual(parser.get_uniform_comparator("ge"), "greater_than_or_equals")
+        self.assertEqual(parser.get_uniform_comparator("ne"), "not_equals")
+
+        self.assertEqual(parser.get_uniform_comparator("str_eq"), "string_equals")
+        self.assertEqual(parser.get_uniform_comparator("len_eq"), "length_equals")
+        self.assertEqual(parser.get_uniform_comparator("count_eq"), "length_equals")
+
+        self.assertEqual(parser.get_uniform_comparator("len_gt"), "length_greater_than")
+        self.assertEqual(parser.get_uniform_comparator("count_gt"), "length_greater_than")
+        self.assertEqual(parser.get_uniform_comparator("count_greater_than"), "length_greater_than")
+
+        self.assertEqual(parser.get_uniform_comparator("len_ge"), "length_greater_than_or_equals")
+        self.assertEqual(parser.get_uniform_comparator("count_ge"), "length_greater_than_or_equals")
+        self.assertEqual(parser.get_uniform_comparator("count_greater_than_or_equals"), "length_greater_than_or_equals")
+
+        self.assertEqual(parser.get_uniform_comparator("len_lt"), "length_less_than")
+        self.assertEqual(parser.get_uniform_comparator("count_lt"), "length_less_than")
+        self.assertEqual(parser.get_uniform_comparator("count_less_than"), "length_less_than")
+
+        self.assertEqual(parser.get_uniform_comparator("len_le"), "length_less_than_or_equals")
+        self.assertEqual(parser.get_uniform_comparator("count_le"), "length_less_than_or_equals")
+        self.assertEqual(parser.get_uniform_comparator("count_less_than_or_equals"), "length_less_than_or_equals")
+
+    def test_parse_validator(self):
+        _validator = {"check": "status_code", "comparator": "eq", "expect": 201}
+        self.assertEqual(
+            parser.uniform_validator(_validator),
+            {"check": "status_code", "comparator": "equals", "expect": 201}
+        )
+
+        _validator = {'eq': ['status_code', 201]}
+        self.assertEqual(
+            parser.uniform_validator(_validator),
+            {"check": "status_code", "comparator": "equals", "expect": 201}
+        )
+
+    def test_extend_validators(self):
+        def_validators = [
+            {'eq': ['v1', 200]},
+            {"check": "s2", "expect": 16, "comparator": "len_eq"}
+        ]
+        current_validators = [
+            {"check": "v1", "expect": 201},
+            {'len_eq': ['s3', 12]}
+        ]
+        def_validators = [
+            parser.uniform_validator(_validator)
+            for _validator in def_validators
+        ]
+        ref_validators = [
+            parser.uniform_validator(_validator)
+            for _validator in current_validators
+        ]
+
+        extended_validators = parser.extend_validators(def_validators, ref_validators)
+        self.assertIn(
+            {"check": "v1", "expect": 201, "comparator": "equals"},
+            extended_validators
+        )
+        self.assertIn(
+            {"check": "s2", "expect": 16, "comparator": "length_equals"},
+            extended_validators
+        )
+        self.assertIn(
+            {"check": "s3", "expect": 12, "comparator": "length_equals"},
+            extended_validators
+        )
+
+    def test_extend_validators_with_dict(self):
+        def_validators = [
+            {'eq': ["a", {"v": 1}]},
+            {'eq': [{"b": 1}, 200]}
+        ]
+        current_validators = [
+            {'len_eq': ['s3', 12]},
+            {'eq': [{"b": 1}, 201]}
+        ]
+        def_validators = [
+            parser.uniform_validator(_validator)
+            for _validator in def_validators
+        ]
+        ref_validators = [
+            parser.uniform_validator(_validator)
+            for _validator in current_validators
+        ]
+
+        extended_validators = parser.extend_validators(def_validators, ref_validators)
+        self.assertEqual(len(extended_validators), 3)
+        self.assertIn({'check': {'b': 1}, 'expect': 201, 'comparator': 'equals'}, extended_validators)
+        self.assertNotIn({'check': {'b': 1}, 'expect': 200, 'comparator': 'equals'}, extended_validators)
+
+
 class TestParser(unittest.TestCase):
 
     def test_parse_parameters_raw_list(self):
@@ -833,11 +932,11 @@ class TestParser(unittest.TestCase):
         dot_env_path = os.path.join(
             os.getcwd(), "tests", ".env"
         )
-        loader.load_dot_env_file(dot_env_path)
+        load.load_dot_env_file(dot_env_path)
         from tests import debugtalk
         cartesian_product_parameters = parser.parse_parameters(
             parameters,
-            functions_mapping=loader.load_module_functions(debugtalk)
+            functions_mapping=load.load_module_functions(debugtalk)
         )
         self.assertIn(
             {
@@ -856,7 +955,7 @@ class TestParser(unittest.TestCase):
         )
 
     def test_parse_parameters_parameterize(self):
-        loader.load_project_tests(os.path.join(os.getcwd(), "tests"))
+        loader.load_project_data(os.path.join(os.getcwd(), "tests"))
         parameters = [
             {"app_version": "${parameterize(data/app_version.csv)}"},
             {"username-password": "${parameterize(data/account.csv)}"}
@@ -868,8 +967,7 @@ class TestParser(unittest.TestCase):
         )
 
     def test_parse_parameters_mix(self):
-        loader.load_project_tests(os.path.join(os.getcwd(), "tests"))
-        project_mapping = loader.project_mapping
+        project_mapping = loader.load_project_data(os.path.join(os.getcwd(), "tests"))
 
         parameters = [
             {"user_agent": ["iOS/10.1", "iOS/10.2", "iOS/10.3"]},
@@ -886,7 +984,7 @@ class TestParser(unittest.TestCase):
     def test_parse_tests_testcase(self):
         testcase_file_path = os.path.join(
             os.getcwd(), 'tests/data/demo_testcase.yml')
-        tests_mapping = loader.load_tests(testcase_file_path)
+        tests_mapping = loader.load_cases(testcase_file_path)
         testcases = tests_mapping["testcases"]
         self.assertEqual(
             testcases[0]["config"]["variables"]["var_c"],
@@ -1272,13 +1370,13 @@ class TestParser(unittest.TestCase):
             parser.eval_lazy_data(content)
 
     def test_extend_with_api(self):
-        loader.load_project_tests(os.path.join(os.getcwd(), "tests"))
+        loader.load_project_data(os.path.join(os.getcwd(), "tests"))
         raw_testinfo = {
             "name": "get token",
             "base_url": "https://github.com",
             "api": "api/get_token.yml",
         }
-        api_def_dict = loader.load_teststep(raw_testinfo)
+        api_def_dict = loader.buildup.load_teststep(raw_testinfo)
         test_block = {
             "name": "override block",
             "times": 3,
diff --git a/tests/test_response.py b/tests/test_response.py
index 633bb6e7..ddd90d54 100644
--- a/tests/test_response.py
+++ b/tests/test_response.py
@@ -1,6 +1,6 @@
 import requests
 
-from httprunner import built_in, exceptions, loader, response
+from httprunner import exceptions, response
 from httprunner.compat import basestring, bytes
 from tests.api_server import HTTPBIN_SERVER
 from tests.base import ApiServerUnittest
@@ -8,9 +8,6 @@ from tests.base import ApiServerUnittest
 
 class TestResponse(ApiServerUnittest):
 
-    def setUp(self):
-        self.functions_mapping = loader.load_module_functions(built_in)
-
     def test_parse_response_object_json(self):
         url = "http://127.0.0.1:5000/api/users"
         resp = requests.get(url)
diff --git a/tests/test_runner.py b/tests/test_runner.py
index 2bc6fc8b..c724ab60 100644
--- a/tests/test_runner.py
+++ b/tests/test_runner.py
@@ -9,8 +9,7 @@ from tests.base import ApiServerUnittest
 class TestRunner(ApiServerUnittest):
 
     def setUp(self):
-        loader.load_project_tests(os.path.join(os.getcwd(), "tests"))
-        project_mapping = loader.project_mapping
+        project_mapping = loader.load_project_data(os.path.join(os.getcwd(), "tests"))
         self.debugtalk_functions = project_mapping["functions"]
 
         config = {
@@ -35,7 +34,7 @@ class TestRunner(ApiServerUnittest):
         ]
 
         for testcase_file_path in testcase_file_path_list:
-            tests_mapping = loader.load_tests(testcase_file_path)
+            tests_mapping = loader.load_cases(testcase_file_path)
             parsed_testcases = parser.parse_tests(tests_mapping)
             parsed_testcase = parsed_testcases[0]
             test_runner = runner.Runner(parsed_testcase["config"])
@@ -289,7 +288,7 @@ class TestRunner(ApiServerUnittest):
     def test_bugfix_type_match(self):
         testcase_file_path = os.path.join(
             os.getcwd(), 'tests/data/bugfix_type_match.yml')
-        tests_mapping = loader.load_tests(testcase_file_path)
+        tests_mapping = loader.load_cases(testcase_file_path)
         parsed_testcases = parser.parse_tests(tests_mapping)
         parsed_testcase = parsed_testcases[0]
         test_runner = runner.Runner(parsed_testcase["config"])
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 7952a5ac..c61eaabe 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -62,8 +62,8 @@ class TestUtils(ApiServerUnittest):
         self.assertEqual(result, "L")
 
     def current_validators(self):
-        from httprunner import built_in
-        functions_mapping = loader.load_module_functions(built_in)
+        from httprunner.builtin import comparators
+        functions_mapping = loader.load.load_module_functions(comparators)
 
         functions_mapping["equals"](None, None)
         functions_mapping["equals"](1, 1)
@@ -108,15 +108,6 @@ class TestUtils(ApiServerUnittest):
         functions_mapping["type_match"]({}, "dict")
         functions_mapping["type_match"]({"a": 1}, "dict")
 
-    def test_deep_update_dict(self):
-        origin_dict = {'a': 1, 'b': {'c': 3, 'd': 4}, 'f': 6, 'h': 123}
-        override_dict = {'a': 2, 'b': {'c': 33, 'e': 5}, 'g': 7, 'h': None}
-        updated_dict = utils.deep_update_dict(origin_dict, override_dict)
-        self.assertEqual(
-            updated_dict,
-            {'a': 2, 'b': {'c': 33, 'd': 4, 'e': 5}, 'f': 6, 'g': 7, 'h': 123}
-        )
-
     def test_handle_config_key_case(self):
         origin_dict = {
             "Name": "test",
diff --git a/tests/test_validator.py b/tests/test_validator.py
index cdaf9563..039c3960 100644
--- a/tests/test_validator.py
+++ b/tests/test_validator.py
@@ -4,170 +4,4 @@ from httprunner import validator
 
 
 class TestValidator(unittest.TestCase):
-
-    def test_is_testcases(self):
-        data_structure = "path/to/file"
-        self.assertFalse(validator.is_testcases(data_structure))
-        data_structure = ["path/to/file1", "path/to/file2"]
-        self.assertFalse(validator.is_testcases(data_structure))
-
-        data_structure = {
-            "project_mapping": {
-                "PWD": "XXXXX",
-                "functions": {},
-                "env": {}
-            },
-            "testcases": [
-                {   # testcase data structure
-                    "config": {
-                        "name": "desc1",
-                        "path": "testcase1_path",
-                        "variables": [],                    # optional
-                    },
-                    "teststeps": [
-                        # test data structure
-                        {
-                            'name': 'test step desc1',
-                            'variables': [],    # optional
-                            'extract': [],      # optional
-                            'validate': [],
-                            'request': {}
-                        },
-                        # test_dict2   # another test dict
-                    ]
-                },
-                # testcase_dict_2     # another testcase dict
-            ]
-        }
-        self.assertTrue(validator.is_testcases(data_structure))
-        data_structure = [
-            {
-                "name": "desc1",
-                "config": {},
-                "api": {},
-                "testcases": ["testcase11", "testcase12"]
-            },
-            {
-                "name": "desc2",
-                "config": {},
-                "api": {},
-                "testcases": ["testcase21", "testcase22"]
-            }
-        ]
-        self.assertTrue(data_structure)
-
-    def test_is_variable(self):
-        var1 = 123
-        var2 = "abc"
-        self.assertTrue(validator.is_variable(("var1", var1)))
-        self.assertTrue(validator.is_variable(("var2", var2)))
-
-        __var = 123
-        self.assertFalse(validator.is_variable(("__var", __var)))
-
-        func = lambda x: x + 1
-        self.assertFalse(validator.is_variable(("func", func)))
-
-        self.assertFalse(validator.is_variable(("unittest", unittest)))
-
-    def test_is_function(self):
-        func = lambda x: x + 1
-        self.assertTrue(validator.is_function(func))
-        self.assertTrue(validator.is_function(validator.is_testcase))
-
-    def test_get_uniform_comparator(self):
-        self.assertEqual(validator.get_uniform_comparator("eq"), "equals")
-        self.assertEqual(validator.get_uniform_comparator("=="), "equals")
-        self.assertEqual(validator.get_uniform_comparator("lt"), "less_than")
-        self.assertEqual(validator.get_uniform_comparator("le"), "less_than_or_equals")
-        self.assertEqual(validator.get_uniform_comparator("gt"), "greater_than")
-        self.assertEqual(validator.get_uniform_comparator("ge"), "greater_than_or_equals")
-        self.assertEqual(validator.get_uniform_comparator("ne"), "not_equals")
-
-        self.assertEqual(validator.get_uniform_comparator("str_eq"), "string_equals")
-        self.assertEqual(validator.get_uniform_comparator("len_eq"), "length_equals")
-        self.assertEqual(validator.get_uniform_comparator("count_eq"), "length_equals")
-
-        self.assertEqual(validator.get_uniform_comparator("len_gt"), "length_greater_than")
-        self.assertEqual(validator.get_uniform_comparator("count_gt"), "length_greater_than")
-        self.assertEqual(validator.get_uniform_comparator("count_greater_than"), "length_greater_than")
-
-        self.assertEqual(validator.get_uniform_comparator("len_ge"), "length_greater_than_or_equals")
-        self.assertEqual(validator.get_uniform_comparator("count_ge"), "length_greater_than_or_equals")
-        self.assertEqual(validator.get_uniform_comparator("count_greater_than_or_equals"), "length_greater_than_or_equals")
-
-        self.assertEqual(validator.get_uniform_comparator("len_lt"), "length_less_than")
-        self.assertEqual(validator.get_uniform_comparator("count_lt"), "length_less_than")
-        self.assertEqual(validator.get_uniform_comparator("count_less_than"), "length_less_than")
-
-        self.assertEqual(validator.get_uniform_comparator("len_le"), "length_less_than_or_equals")
-        self.assertEqual(validator.get_uniform_comparator("count_le"), "length_less_than_or_equals")
-        self.assertEqual(validator.get_uniform_comparator("count_less_than_or_equals"), "length_less_than_or_equals")
-
-    def test_parse_validator(self):
-        _validator = {"check": "status_code", "comparator": "eq", "expect": 201}
-        self.assertEqual(
-            validator.uniform_validator(_validator),
-            {"check": "status_code", "comparator": "equals", "expect": 201}
-        )
-
-        _validator = {'eq': ['status_code', 201]}
-        self.assertEqual(
-            validator.uniform_validator(_validator),
-            {"check": "status_code", "comparator": "equals", "expect": 201}
-        )
-
-    def test_extend_validators(self):
-        def_validators = [
-            {'eq': ['v1', 200]},
-            {"check": "s2", "expect": 16, "comparator": "len_eq"}
-        ]
-        current_validators = [
-            {"check": "v1", "expect": 201},
-            {'len_eq': ['s3', 12]}
-        ]
-        def_validators = [
-            validator.uniform_validator(_validator)
-            for _validator in def_validators
-        ]
-        ref_validators = [
-            validator.uniform_validator(_validator)
-            for _validator in current_validators
-        ]
-
-        extended_validators = validator.extend_validators(def_validators, ref_validators)
-        self.assertIn(
-            {"check": "v1", "expect": 201, "comparator": "equals"},
-            extended_validators
-        )
-        self.assertIn(
-            {"check": "s2", "expect": 16, "comparator": "length_equals"},
-            extended_validators
-        )
-        self.assertIn(
-            {"check": "s3", "expect": 12, "comparator": "length_equals"},
-            extended_validators
-        )
-
-    def test_extend_validators_with_dict(self):
-        def_validators = [
-            {'eq': ["a", {"v": 1}]},
-            {'eq': [{"b": 1}, 200]}
-        ]
-        current_validators = [
-            {'len_eq': ['s3', 12]},
-            {'eq': [{"b": 1}, 201]}
-        ]
-        def_validators = [
-            validator.uniform_validator(_validator)
-            for _validator in def_validators
-        ]
-        ref_validators = [
-            validator.uniform_validator(_validator)
-            for _validator in current_validators
-        ]
-
-        extended_validators = validator.extend_validators(def_validators, ref_validators)
-        self.assertEqual(len(extended_validators), 3)
-        self.assertIn({'check': {'b': 1}, 'expect': 201, 'comparator': 'equals'}, extended_validators)
-        self.assertNotIn({'check': {'b': 1}, 'expect': 200, 'comparator': 'equals'}, extended_validators)
+    pass