HttpRunner 2.0 is comming!

1, new design for testcase format;
2, refactor testcase layer mechanism.

tests/testsuites/create_users.yml

@@ -0,0 +1,17 @@
+- config:
+    name: create users with uid
+    variables:
+        - device_sn: ${gen_random_string(15)}
+    base_url: "http://127.0.0.1:5000"
+
+- test:
+    name: create user 1000 and check result.
+    testcase: testcases/create_and_check.yml
+    variables:
+        - uid: 1000
+
+- test:
+    name: create user 1001 and check result.
+    testcase: testcases/create_and_check.yml
+    variables:
+        - uid: 1001