Fake it until you make it. Integration Testing with Testcontainers and WireMock - Spring Boot Edition

Pair presentation together with Oleg Šelajev at Devoxx Belgium 2023

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 API testing frameworks like WireMock. 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 modules and integrations. 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 and maybe Golang examples, but the same approaches can be used in any technology stack for which the Testcontainers SDK is available.

OLEG NENASHEV
Oleg is a developer tools hacker, community builder and consultant currently working on WireMock and WireMock Cloud ecosystems. He's passionate open source software and open hardware advocate. Oleg is a core maintainer and board member in the Jenkins project where he writes code, mentors contributors and organizes community events. He is a TOC member in the Continuous Delivery Foundation, and also a CDF and CNCF ambassador. Oleg has a PhD degree in electronics design and volunteers in the Free and Open Source Silicon Foundation.

OLEG ŠELAJEV
Oleg Šelajev is a developer advocate at AtomicJar working on making integration tests with Testcontainers better for everyone in the community. VirtualJUG leader. Java Champion.

Transcript

1. Fake it until you make it API Integration testing with Testcontainers and WireMock Oleg Nenashev, WireMock Oleg Šelajev, AtomicJar
7. Why are we here? 7 • Shift left your integration testing • Mocking APIs and services, reducing external dependencies, containers • There are tools for that, including WireMock and Testcontainers • They work well together! These slides
8. > whoami @oleg_nenashev oleg-nenashev Dr. Nenashev / Mr. Jenkins Developer tools hacker Community builder & DevRel consultant #RussiansAgainstPutin #StandWithUkraine
11. 11 Staging & QA Tests Build Integration tests Gaining confidence in you software
12. 12 Staging & QA Tests Build Integration tests Build Tests Gaining confidence in you software
15. Debug your Testcontainers- powered dependencies The app lets you proxy any service to a fixed port to easily inspect it with your favorite debugging tools. Track and analyze your test sessions Dashboards that provide you and your team with insights into your development and testing patterns. Switch container runtimes and burst to the cloud With Testcontainers Cloud, you can even run them in the cloud on demand, while saving your local resources. Testcontainers Desktop The free companion app.
18. 18 Source: https://medium.com/10-minutes-qa-story/api-testing-from-scratch-api-anatomy-f220856ce9b3
19. APIs
20. Ways to do API integration testing 1. Testing against Production/Staging servers 2. Testing against a simplified/containerized instance (with Testcontainers) 3. Mocking at the API provider level 4. Mocking at the code level 20 Slow Fast Accu- rate Nope
22. 22 WireMock 101 WireMock is a tool for building mock APIs Created in 2011 as a Java test library and CLI You can can: • Create stable development environments • Isolate yourself from flakey 3rd parties • Simulate APIs that don't exist yet • Extend everything wiremock.org
23. 23 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
24. WireMock Ecosystem & Features 24 wiremock.org/docs
25. WireMock Ecosystem & Features 25 wiremock.org/docs
26. WireMock in Java 26 wiremock.org/docs/stubbing
27. WireMock Ecosystem & Features 27 wiremock.org/docs
28. WireMock & JVM Ecosystem - projects for… • Java • Kotlin • Scala • Groovy • Clojure • (?)Android 28 • JUnit 4/5 • Testcontainers • Sprint Boot • Spring Cloud Contract • Quarkus • Maven/Gradle • Spock • Pact
29. Example - WireMock for Rust 29 docs.rs/wiremock/latest/wiremock LukeMathWalker/wiremock-rs Note: WireMock for Rust is maintained outside the WireMock GitHub organization
30. 30 2500+ Mock API Templates for common services library.wiremock.org
31. WireMock Distributions 31
32. WireMock Cloud by WireMock Inc. 32 • Early stage startup • WireMock creator is a co-founder of the Inc. • WireMock Cloud - SaaS for end-to-end API mocking • Private beta: K8s Edition for managed / on-premises wiremock.io
33. 33 Better Together!
35. 35 WireMock offers an official Testcontainers module! testcontainers.com/modules/wiremock
36. Example - JUnit 5 36
38. Example 1 - Testing of WireMock Docker images 38 • Java, Testcontainers, JUnit5 • Sources location: github.com/wiremock/wiremock-docker /tree/main/test/integration-tests
39. Example 2 - Golang 39 • Golang, Testcontainers, WireMock Module • Sources location: github.com/wiremock/wiremock-testcontain ers-go/tree/main/examples/quickstart
42. WireMock as a Proxy 42 Tests API Provider • Fault injection • Recording • Protocol Verification
44. Mega Demo - Spring Boot App development … with a database and a Mock API server for Hacker News API See github.com/shelajev/testcontainers-wiremock-demo 44
45. 45 Let’s talk at Booth #20
46. It’s [always] a great time to contribute! wiremock.org/participate testcontainers.org/contributing 46
47. THANK YOU 47 wiremock.org/testcontainers slack.wiremock.org slack.testcontainers.com github.com/shelajev/testcontainers-wiremock-demo wiremock.org testcontainers.com 🏢
48. Credits to • All WireMock contributors • WireMock Inc. Team • All Testcontainers contributors and AtomicJar folks • All FOSS contributors 48