The power of mocking APIs

Blocked because the API you depend on doesn’t exist yet or isn’t completely ready? Facing trouble to test various scenarios due to lack of control over third-party APIs? Struggling to test failure cases like receiving an invalid response , 5XX errors and so on? Having flaky tests due to slow API responses?

These are some very common problems we encounter. We cannot rely on slow APIs, which provide a very narrow range of responses. So how can we test effectively in such situations? Is there any feasible solution available? Fortunately, there is: stubbing the APIs.

This presentation is about creating a mock server and stub responses to get rid of other dependencies.

Below are links used for demo in the presentation

Weather application source code-
https://github.com/ShivaniGaba1/weather-app/

Wiremock project code-
https://github.com/ShivaniGaba1/wiremock-weather/

Transcript

1. The power of mocking APIs
2. Shivani Gaba Lead QA @New Work SE @shivani_gaba_
3. Know why? @shivani_gaba_
4. Complicated system @shivani_gaba_
5. Tell my story @shivani_gaba_
6. Explore together @shivani_gaba_
7. Weather check @shivani_gaba_
8. Quick look @shivani_gaba_
9. x Client API request API response Server @shivani_gaba_
10. Control API @shivani_gaba_
11. OpenWeather Server Mock Server Client Stubbed response @shivani_gaba_
12. • Easy to setup and configure • Offer various features • Can be stand-alone or embedded • Active community supports Wiremock Approach over tools @shivani_gaba_
13. Setup @shivani_gaba_
14. @shivani_gaba_ Setup video
15. Remove dependencies @shivani_gaba_
16. Scenario 1: Difficult to reproduce @shivani_gaba_
17. Video 1 @shivani_gaba_
18. Similar ideas - • Set any response body • Complicated Cases • Edge cases @shivani_gaba_
19. Scenario 2: Invalid responses @shivani_gaba_
20. @shivani_gaba_ Video 2
21. Similar ideas - • Body - Corrupt format - Missing mandatory fields • Headers - Missing headers - Invalid headers …. @shivani_gaba_
22. Scenario 3: API responsiveness @shivani_gaba_
23. Video 3 @shivani_gaba_
24. Scenario 4: Errors and faults @shivani_gaba_
25. Video 4 & 5 @shivani_gaba_
26. Similar ideas- • Any status codes - Server side 5XX (ISE, service unavaible etc) - Client error 4XX (bad request, rate limiting etc) - Non-error codes • Faults - Connection_reset, random_data_close etc. @shivani_gaba_
27. Scenario 5: API not ready @shivani_gaba_
28. Profile API not ready @shivani_gaba_
29. Only help testing web apps? x @shivani_gaba_
30. UI Microservice @shivani_gaba_ UI Microservice
31. UI Microservice Microservice Microservice Microservice Microservice Inspiration- @JostenRosanne Microservice Microservice @shivani_gaba_ Microservice Microservice Microservice
32. x System under test
33. x System under test Mock
34. Pros • Test in isolation • Reduce dependencies • Parallel development • Realiable • Fast response • Test complicated/edge cases • Test delays • Prevents rate limiting Cons • Maintainance • Complexity increase @shivani_gaba_
35. Interesting to explore @shivani_gaba_
36. Can also be stubbed here Integration E2E Unit Stubbed here Unit E2E Integration @shivani_gaba_
37. Embedded wiremock Standalone wiremock Client Client Standalone wiremock Embedded wiremock @shivani_gaba_ Integration tests setup Unit tests setup
38. Client @Rule public WireMockRule wireMockRule = new WireMockRule(int port); wireMockRule.start(); public void stubWithServiceUnavailable() { /** Stub with service unavailable**/ stubFor(get(urlEqualTo("/getSomething”)) .willReturn(aResponse() .withStatus(503))); } If application is in same framework, then- @shivani_gaba_
39. Summary • How & why to setup mock servers • Stub responses • Test in isolation • Different levels of testing • Check weather @shivani_gaba_
40. Project Links @shivani_gaba_ • Weather application source code- https://github.com/ShivaniGaba1/weather-app/ • Wiremock project code- https://github.com/ShivaniGaba1/wiremock-weather/
41. References @shivani_gaba_ https://martinfowler.com/bliki/TestDouble.html https://medium.com/@kapil.aggarwal1 https://github.com/basdijkstra/wiremock-workshop Martin Fowler Bas Dijkstra Kapil Aggarwal http://wiremock.org/docs/running-standalone/ Wiremock docs
42. @shivani_gaba_ https://www.pikist.com/free-photo-skfzz https://publicdomainvectors.org/ https://www.iconsdb.com/ https://commons.wikimedia.org/ https://flickr.com/ https://www.pxfuel.com/ https://cliparts.zone/ https://giphy.com/ https://pixabay.com/ Image courtesy
43. Questions @shivani_gaba_