![Request attributes
_Many different request attributes available for use
_ request.method : HTTP method (example)
_ request.pathSegments.[<n>] : nth
path segment
_ request.headers.<key> : header with name key
_ …
_All available attributes listed at
https://wiremock.org/docs/response-templating/](https://image.slidesharecdn.com/wiremockworkshop-241007172117-45351e2c/85/Wire-Mock-API-implementation-using-JAVA-wiremock_workshop-pptx-51-320.jpg)
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- 1. No API? No problem! API mocking with WireMock An open source workshop by … Originally created by Bas Dijkstra – [email protected] – https://www.ontestautomation.com
- 2. What are we going to do? _Stubbing, mocking and service virtualization _WireMock _Exercises, examples, …
- 3. Preparation _Install JDK (Java 17 or newer) _Install IntelliJ IDEA (or any other IDE) _Download or clone project _Import Maven project in IDE
- 4. Section 0: An introduction to service virtualization
- 5. Problems in test environments _Systems are constructed out of of many different components _Not all of these components are always available for testing _Parallel development _No control over test data _Fees required for using third party components _…
- 6. Problems in test environments System under test Mainframe SaaS dependency Backend system Mobile app No suitable test data Limited access Under development Access fees
- 7. Simulation during test execution _Simulate dependency behaviour _Regain full control over test environment _Available on demand _Full control over test data (edge cases!) _No third party component usage fees _…
- 8. Problems in test environments System under test Mainframe SaaS dependency Backend system Mobile app No suitable test data Limited access Under development Access fees
- 9. Simulation in test environments System under test Virtualized mainframe Virtualized SaaS dependency Virtualized backend system Virtualized mobile app Unrestricted access Unrestricted access Unrestricted access Unrestricted access
- 11. API consumer API provider request response System Simulating APIs for more efficient testing and automation Simulation
- 12. Our system under test _ParaBank _The world’s least safe online bank _Request Loan process _Loan application is processed by 3rd party loan provider component
- 13. Loan Processor service A P I ParaBank middleware A P I Frontend / API client 3rd party development team ParaBank development team
- 15. What might we want to simulate? Start testing against features under development Delays, fault status codes, malformatted responses, … … Easy setup of state for edge cases
- 16. Section 1: Getting started with WireMock
- 17. WireMock _https://wiremock.org _Java _ports and adapters are available for many other languages _HTTP mock server _only supports HTTP(S) _Open source
- 19. Starting WireMock (JUnit 4) _Via JUnit 4 @Rule _Without using JUnit 4 @Rule
- 20. Starting WireMock (JUnit 5) _Uses the JUnit 5 Jupiter extension mechanism _Via @WireMockTest class annotation (basic configuration) _Programmatically using @RegisterExtension (full control)
- 21. Starting WireMock (standalone) _Useful for exploratory testing purposes _Allows you to share WireMock instances between teams _Long-running instances _Download the .jar first java -jar wiremock-standalone-3.3.1.jar --port 9876
- 22. Configure responses _In (Java) code _Using JSON mapping files
- 23. An example mock defined in Java
- 24. Some useful WireMock features _Verification _ Verify that certain requests are sent by application under test _Record and playback _ Generate mocks based on request-response pairs (traffic) _Fault simulation _… _Full documentation at https://wiremock.org/docs/
- 25. Now it’s your turn! _exercises > WireMockExercises1Test.java _Create a couple of basic mocks _ Implement the responses as described in the comments _Verify your solution by running the tests in the same file _Answers are in answers > WireMockAnswers1Test.java _Examples are in examples > WireMockExamplesTest.java
- 26. Section 2: Request matching strategies and fault simulation
- 27. Request matching _Send a response only when certain properties in the request are matched _Options for request matching: _URL _HTTP method _Query parameters _Headers _Request body elements _…
- 28. Example: URL matching _Other URL options: _urlPathEqualTo (matches only path, no query parameters) _urlMatching (using regular expressions) _urlPathMatching (using regular expressions)
- 29. Example: header matching _absent(): check that header is not in request
- 30. Example: using logical AND and OR _‘somevalue’ is matched _‘bananasomevaluebanana’ is matched _‘banana’ is not matched (does not contain ‘somevalue’) _‘123somevalue’ is not matched (contains numeric characters)
- 31. Some more examples… Same behaviour as the previous example, using a slightly different syntax
- 32. Matching on request body elements Matching only those request bodies that have a root level element fruits with a child element banana with value 2 {“fruits”: {“banana”: “2”, “apple”: “5”} } MATCH {“fruits”: {“apple”: “5”} } NO MATCH {“fruits”: {“banana”: “3”, “apple”: “5”} } NO MATCH
- 33. Matching using date/time properties Matching all dates after midnight of July 1, 2021 Matching all dates at least 1 month before the current date
- 34. Other matching strategies _Authentication (Basic, OAuth(2)) _Query parameters _Multipart/form-data _You can write your own matching logic, too
- 35. Fault simulation _Extend test coverage by simulating faults _Often hard to do in real systems _Easy to do using stubs or mocks _Used to test the exception handling of your application under test
- 36. Example: HTTP status code _Some often used HTTP status codes: Consumer error Provider error 403 (Forbidden) 500 (Internal server error) 404 (Not found) 503 (Service unavailable)
- 37. Example: timeout _Random delay can also be used _Uniform, lognormal distribution _Can be configured on a per-stub basis as well as globally
- 38. Example: bad response _HTTP status code 200, but garbage in response body _Other options: _RANDOM_DATA_THEN_CLOSE (as above, without HTTP 200) _EMPTY_RESPONSE (does what it says on the tin) _CONNECTION_RESET_BY_PEER (close connection, no response)
- 39. Now it’s your turn! _exercises > WireMockExercises2Test.java _Practice fault simulation and different request matching strategies _ Implement the responses as described in the comments _Verify your solution by running the tests in the same file _Answers are in answers > WireMockAnswers2Test.java _Examples are in examples > WireMockExamplesTest.java
- 40. Section 3: Creating stateful mocks
- 41. Statefulness _Sometimes, you want to simulate stateful behaviour _Shopping cart (empty / containing items) _Database (data present / not present) _Order in which requests arrive is significant
- 42. Stateful mocks in WireMock _Supported through the concept of a Scenario _Essentially a finite state machine (FSM) _States and state transitions _Combination of current state and incoming request determines the response being sent _Before now, it was only the incoming request
- 43. Stateful mocks: an example Responses are grouped by scenario name Response depends on both the incoming request as well as the current state The initial state should always be Scenario.STARTED Incoming requests can trigger state transitions State names other than Scenario.STARTED are yours to define
- 44. Now it’s your turn! _exercises > WireMockExercises3Test.java _Create a stateful mock that exerts the described behaviour _ Implement the responses as described in the comments _Verify your solution by running the tests in the same file _Answers are in answers > WireMockAnswers3Test.java _Examples are in examples > WireMockExamplesTest.java
- 46. Response templating _Often, you want to reuse elements from the request in the response _Request ID header _Unique body elements (client ID, etc.) _Cookie values _WireMock supports this through response templating
- 47. Setup response templating (JUnit 4) _In code: through the JUnit @Rule _Global == false: response templating transformer has to be enabled for individual stubs
- 48. Setup response templating (JUnit 5) _In code: through the JUnit @RegisterExtension _Argument == false: response templating has to be enabled for individual stubs
- 49. Enable/apply response templating _This template reads the HTTP request method (GET/POST/PUT/…) using {{request.method}} and returns it as the response body This call to withTransformers() is only necessary when response templating isn’t activated globally
- 50. One thing to keep in mind… … we need to explicitly assign our stub definition to that instance here, or else the stub definition will not be picked up! Because we’re explicitly initializing a WireMock instance here…
- 51. Request attributes _Many different request attributes available for use _ request.method : HTTP method (example) _ request.pathSegments.[<n>] : nth path segment _ request.headers.<key> : header with name key _ … _All available attributes listed at https://wiremock.org/docs/response-templating/
- 52. Request attributes (cont’d) _Extracting and reusing body elements _In case of a JSON request body: {{jsonPath request.body ‘$.path.to.element’}} _In case of an XML request body: {{xPath request.body ‘/path/to/element/text()’}}
- 53. JSON extraction example _When sent this JSON request body: _This stub returns a response with body “Pillars of the Earth”: Again, this call to withTransformers() is only necessary when response templating isn’t activated globally
- 54. Now it’s your turn! _exercises > WireMockExercises4Test.java _Create mocks that use response templating _ Implement the responses as described in the comments _Verify your solution by running the tests in the same file _Answers are in answers > WireMockAnswers4Test.java _Examples are in examples > WireMockExamplesTest.java
- 56. Verifying incoming requests _Apart from returning responses, you might also want to verify that incoming requests have certain properties _Fail a test if these verifications aren’t met _You can do this with WireMock in a way very similar to mocking frameworks for unit tests (e.g., Mockito for Java)
- 57. Verifying incoming requests Given this simple ‘hello world’ stub When we have this test that should invoke that stub exactly once Then this verification can be added to the test to ensure that indeed, an HTTP GET to ‘/hello-world’ has been made exactly once
- 58. Some more verification examples The same as the above, but less verbose Verify that less than 5 HTTP POSTs were made to /requestLoan Verify that 10 or more HTTP POSTs with a ‘Content-Type’ header value containing ‘application/json’ were made to /requestLoan
- 59. Now it’s your turn! _exercises > WireMockExercises5Test.java _Add WireMock verifications to the tests _ Verify request properties as described in the comments _Verify your solution by running the tests _Answers are in answers > WireMockAnswers5Test.java _Examples are in examples > WireMockExamplesTest.java
- 61. Extending WireMock _In some cases, the default WireMock feature set might not fit your needs _WireMock is open to extensions _Allows you to create even more powerful stubs _Several options available
- 63. Request filtering _Modify incoming requests (or halt processing) _This has a variety of use cases: _Checking authentication details _Request header injection _URL rewriting _Created by implementing the StubRequestFilterV2 interface
- 64. Request filtering – build If the HTTP verb used equals DELETE… Return an HTTP 403 and stop processing the request Else continue processing the request
- 65. Request filtering – use An extension can be registered using: - its class name (“com.example.HttpDeleteFilter”) - the class (HttpDeleteFilter.class) - an instance (new HttpDeleteFilter())
- 66. Now it’s your turn! _exercises > extensions > BasicAuthFilter.java _Implement a custom request filter that filters out all requests that do not have the proper basic authentication credentials _Verify your solution by running the tests in exercises > WireMockExercises6dot1Test.java _Answers are in answers > extensions > BasicAuthFilter.java _Examples are in examples > extensions > HttpDeleteFilter.java
- 67. Section 6.2: Building a custom request matcher
- 68. Custom request matchers _Add custom request matching logic to WireMock _Can be combined with existing standard matchers _Done by extending RequestMatcherExtension class
- 69. Custom request matcher – build Get the value of the maxLength matcher parameter Compare the request body length to the maxLength parameter value and return the result as a MatchResult
- 70. Custom request matcher – use Register the extension Use custom matcher in a stub definition using its name (can be combined with existing matchers) Specify desired parameter value
- 71. Now it’s your turn! _exercises > extensions > RejectedHttpVerbsMatcher.java _Implement a custom matcher that reads a list of rejected HTTP verbs and matches the HTTP verb used in the incoming request against it _Verify your solution by running the tests in exercises > WireMockExercises6dot2Test.java _Answers are in answers > extensions > RejectedHttpVerbsMatcher.java _Examples are in examples > extensions > BodyLengthMatcher.java
- 72. Section 6.3 is waiting on https://github.com/wiremock /wiremock/issues/2525 to be resolved
- 74. Appendix A: JSON equivalents for the Java examples
- 75. Our Hello world! mock
- 76. URL matching
- 79. Returning a fault response
- 82. Use response templating _When sent this JSON request body: _This stub returns a response with body “Pillars of the Earth”:
- 83. Using WireMock extensions Using a custom matcher Registering a local transformer Specifying transformer parameters
- 84. ?