Fake it until you make it. ITs with WireMock, Testcontainers and Quarkus

Testcontainers has become one of the most popular tools for software integration testing. If you can put your system-under-test into a container, Docker compose cluster or a pod, this is what you're likely to use. If your target isn't ready, not containerizable or just too heavy for testing as is, you can always use mock testing frameworks, e.g. WireMock or MockServer in the JVM ecosystem. Can you combine both approaches? Sure!

In this talk, we will classify integration testing and discuss application areas for WireMock and Testcontainers, and discuss which tool to choose for each use-case. And why not both? We will discuss putting WireMock into Testcontainers, and getting the best from their features thanks to the new WireMock modules for Testcontainers. Last but not least, we will see how to put WireMock in front of the Testcontainers or your real system to do deeper tests or even chaos engineering.

P.S: We will focus on the Java, Golang or Rust examples, but the same approaches can be used everywhere

Copyright Notice: Gradle, Inc. Gradle®, Develocity®, Build Scan®, and the Gradlephant logo are registered trademarks of Gradle, Inc. "Gradle" means "Gradle Build Tool" and does not reference Gradle, Inc. and/or its subsidiaries

Transcript

1. Oleg Nenashev @oleg_nenashev Fake it until you `make it` API Integration testing with Testcontainers, WireMock and Quarkus IET Summit, 27 January 2025
2. > whoami @oleg_nenashev oleg-nenashev Dr. Nenashev / Mr. Jenkins Community Builder Developer Tools Hacker Independent Consultant #RussiansAgainstPutin #StandWithUkraine
3. rts.ch/info/regions/neuchatel/12836885-la-population-neuchateloise-en-hausse-malgre-un-recul-dans-les-montagnes.html
4. Async Q&A: Testcontainers and WireMock Slack speakerdeck.com/onenashev
5. About You 6
6. When IT Goes wrong 7
9. Do you `make it`? IT - Integration Tests 10
11. Integration Testing 12 • Multiple technology stacks and toolchains • Many teams involved • Sacred knowledge • [Almost] always too late
14. APIs are the Key for Developer Productivity response request Client App Server HTTP/2 Storage response request API API
15. API specs API tech
17. 18 Staging & QA Tests Build Integration tests Build Tests Gaining confidence in you software “Shift Left” with modern tools
18. 19 https://martinfowler.com/articles/ mocksArentStubs.html
19. Ways to do API integration testing 1. Testing against Production/Staging servers 2. Testing against a simplified/containerized instance (e.g. Testcontainers) 3. Modeling (aka Mocking) at the API provider level (e.g. WireMock) 4. Mocking at the code level Slow Fast Nope Accu- rate * For Testcontainers, see the slides
20. Ways to do API integration testing 1. Testing against Production/Staging servers 2. Testing against a simplified/containerized instance (e.g. Testcontainers) 3. Modeling (aka Mocking) at the API provider level (e.g. WireMock or Microcks) 4. Mocking at the code level Slow Fast Nope Accu- rate * For Testcontainers, see the slides
22. Example - Java 23
23. https://testcontainers.com/modules/
24. 25 LOCAL STACK https://testcontainers.com/modules/
25. 26 SDKs testcontainers.org … and
26. 27 github.com/testcontainers/ testcontainers-go
27. Demo Time 28 github.com/oleg-nenashev/mocks-as-code-demo/ tree/main/1_application
28. No Implementation? 29 Fake it until you “$ make it”
29. Ways to do API integration testing 1. Testing against Production/Staging servers 2. Testing against a simplified/containerized instance (e.g. Testcontainers) 3. Modeling (aka Mocking) at the API provider level (e.g. WireMock or Microcks) 4. Mocking at the code level Slow Fast Nope Accu- rate * For Testcontainers, see the slides
30. API Mocking for Java. Examples en.wikipedia.org/wiki/Comparison_of_API_simulation_tools Proprietary Open Source `
31. API Mocking Tools Main implementation in Java Native lib, Docker images and Testcontainers modules Support for GraalVM Rich Ecosystem Sandbox CNCF Project Golang / Microservice arch Docker image, Testcontainers module, All-in K8s Charts Less Rich Ecosystem
33. wiremock.org/docs/stubbing IF (request_url) THEN (response) * * it gets MUCH more complex WireMock Config JSON: Client library response request Client App Mock API Server HTTP/2 API Mocking 101
34. WireMock Ecosystem & Features wiremock.org/docs
35. WireMock Ecosystem wiremock.org/docs
36. WireMock in Java wiremock.org/docs/stubbing * Gradle® and the Gradlephant logo are registered trademarks of Gradle, Inc.
37. WireMock Ecosystem / Java • Java • Kotlin • Scala • Groovy • Clojure • (?)Android 38 • JUnit 4/5 • Testcontainers • Sprint Boot • Spring Cloud Contract • Quarkus • Maven / Gradle Build Tool • Spock • Pact * Gradle® and the Gradlephant logo are registered trademarks of Gradle, Inc. "Gradle" means "Gradle Build Tool" and does not reference Gradle, Inc. and/or its subsidiaries
38. Example - JUnit 5 39
39. 40 WireMock has an official Testcontainers module! testcontainers.com/modules/wiremock
40. WireMock as a Proxy Tests API Provider • Fault injection • Recording • Protocol Verification
41. 42 DEMO TIME https://github.com/wiremock/wiremock-docker
42. WireMock or Testcontainers?
43. Choosing a right tool * • Need database or complex dynamic environment? ◦ YES => Testcontainers • Do you have a ready implementation? ◦ NO => WireMock/Microcks • Is it containerized and lightweight? ◦ NO => WireMock/Microcks • Can you easily trigger the desired scenarios? ◦ NO => WireMock/Microcks • Else: => Testcontainers 44 * Your mileage may vary ** More later *** I just like footnotes * Likely, you want to use both
45. 46 WireMock has an official Testcontainers module! testcontainers.com/modules/wiremock
46. Proxy can be made transparent in your test! 47 Tests
47. WireMock Proxy? Why? • Record & Playback for Request sequences • Reverse engineering of legacy undocumented APIs • NEW: OpenAPI Standard Compliance Verification (in 3.0 Beta) • Emulating complex cases ◦ Overriding particular responses ◦ Emulating response sequences / Stateful behavior ◦ Failure Injection 48
48. Quarkus or Spring What do you use ?
49. If you like / use You can do [almost] the same as below Devoxx BE Video with Oleg Shelajev: youtube.com/watch?v=eFILbyaMI2A Our demo: github.com/testcontainers-community/ testcontainers-wiremock-demo 50 TL;DR: Two Olegs
50. Source: https://www.codelikethewind.org/2022/05/03/3-reasons- why-all-java-developers-should-consider-quarkus/ • Reference implementation of new Java Developer Experience • Spring Boot is catching up • Micronaut & Co are great, too
51. Quarkus Dev Services • Automatic provisioning of unconfigured services in development and test mode • Transparent to your application • Mostly containerized, with Testcontainers 52 https://quarkus.io/guides/dev-services
52. Dev Services • Mostly containerized, with Testcontainers 53 Presentation by Daniel Oh: https://www.youtube.com/watch?v=moIFTj9KW1c
54. 55 docs.quarkiverse.io/quarkus-wiremock/dev/index.html
55. @QuarkusTest or @QuarkusIntegrationTest
56. And a Quarkus Dev Service! docs.quarkiverse.io/quarkus-wiremock/dev/index.html
57. docs.quarkiverse.io/qu arkus-wiremock/dev/in dex.html#extension-co nfiguration-reference
58. 59 DEMO TIME https://github.com/oleg-nenashev/gradle-quarkus-plugin-demo
60. More Demos • Simple WireMock and Testcontainers demo: github.com/testcontainers-community/testcontainers-wiremock-demo • WireMock and Docker integration tests: https://github.com/wiremock/wiremock-docker • Quarkus Dev Service for WireMock and Testcontainers: https://github.com/oleg-nenashev/gradle-quarkus-plugin-demo • Spring Boot + Testcontainers and WireMock + LocalStack: https://github.com/oleg-nenashev/mocks-as-code-demo
61. Lessons Learned 62
62. Takeaways 63 • Shift left the integration testing • API Mocking / abstraction are great… when used right • There is no silver bullet • WireMock and Testcontainers address their own use-cases • They work well together!
63. Choosing a right tool * • Need database or complex dynamic environment? ◦ YES => Testcontainers • Do you have a ready implementation? ◦ NO => WireMock/Microcks • Is it containerized and lightweight? ◦ NO => WireMock/Microcks • Can you easily trigger the desired scenarios? ◦ NO => WireMock/Microcks • Else: => Testcontainers 64 * Your mileage may vary ** More later *** I just like footnotes * Likely, you want to use both
64. Keep Learning Tools 65 * AKA: Burning Out 101
66. It’s [always] a great time to contribute! testcontainers.org/contributing wiremock.org/participate 67
67. GitHub: oleg-nenashev Twitter: @oleg_nenashev WireMock Slack Questions? Testcontainers Slack 68
68. Credits 69 • All WireMock, Testcontainers and Quarkus contributors • Siva Prasad Reddy, JetBrains and Oleg Shelajev, Docker • All FOSS folks