feat: support api layer and global headers for testcase

examples/ref_api_test.yaml

@@ -0,0 +1,47 @@
+config:
+  name: 'api test demo'
+  variables:
+    user_agent: iOS/10.3
+    device_sn: TESTCASE_SETUP_XXX
+    os_platform: ios
+    app_version: 2.8.6
+  base_url: 'https://postman-echo.com'
+  herader:
+    - Accept: '*/*'
+      Accept-Encoding: 'gzip, deflate, br'
+      Cache-Control: no-cache
+      Connection: keep-alive
+      Host: postman-echo.com
+      User-Agent: PostmanRuntime/7.28.4
+  verify: false
+  export:
+    - session_token
+teststeps:
+  - name: 'test api /get'
+    api: examples/api/get.json
+    variables:
+      user_agent: iOS/10.4
+      device_sn: $device_sn
+      os_platform: ios
+      app_version: 2.8.7
+    extract:
+      session_token: 'body.headers."postman-token"'
+  - name: 'test api /post'
+    api: examples/api/post.json
+    variables:
+      user_agent: iOS/10.5
+      device_sn: $device_sn
+      os_platform: ios
+      app_version: 2.8.9
+    validate:
+      - { eq: [ status_code, 200 ] }
+      - { eq: [ body.headers.postman-token, ea19464c-ddd4-4724-abe9-5e2b254c2723 ] }
+  - name: 'test api /put'
+    api: examples/api/put.json
+    variables:
+      user_agent: iOS/10.6
+      device_sn: $device_sn
+      os_platform: ios
+      app_version: 2.8.10
+    extract:
+      session_token: 'body.headers."postman-token"'