Testcontainers for your Golang projects

Quick overview of the Testcontainers for integration testing in your Golang projects, with WireMock as an example

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1. Oleg Nenashev, @oleg_nenashev CNCF Ambassador
2. Oleg Nenashev @oleg_nenashev oleg-nenashev Community builder Developer Tools Hacker Testcontainers Champion Cloud Native Suisse Romande #RussiansAgainstPutin #StandWithUkraine
5. When IT Goes wrong
6. Do you `make it`? IT - Integration Tests
8. Integration Testing • Multiple technology stacks and toolchains • Many teams involved • Sacred knowledge • [Almost] always too late
11. Async Q&A: Testcontainers Slack speakerdeck.com/onenashev
12. Build Unit tests Publish Reports Integration tests Publish Reports NOW “Shift Left” Fast integrations tests are critical
13. Ways to do integration testing 1. Testing against Production/Staging Slow Fast Nope Accu- rate 2. Testing against a simplified/containerized instance (e.g. Testcontainers) 4. Mocking at the code level (e.g. GoMock) 3. Mocking at the API provider level (e.g. Microcks, WireMock)
16. SDKs testcontainers.org … and
17. github.com/testcontainers/ testcontainers-go
18. 60+ Testcontainers Modules for Golang testcontainers.com/modules/?language=go
19. WireMock has an official Testcontainers module! testcontainers.com/modules/wiremock
20. Ways to do integration testing 1. Testing against Production/Staging Slow Fast Nope Accu- rate 2. Testing against a simplified/containerized instance (e.g. Testcontainers) 4. Mocking at the code level (e.g. GoMock) 3. Mocking at the API provider level (e.g. Microcks, WireMock)
21. 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
22. API Mocking for Java. Examples en.wikipedia.org/wiki/Comparison_of_API_simulation_tools Proprietary Open Source `
23. 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
24. WireMock for Go Testcontainers Module REST API Client Go test integrations go.wiremock.org github.com/wiremock/wiremock-testcontainers-go
25. DEMO - API Mocking with WireMock • Golang, Testcontainers, WireMock Module • Sources location: github.com/wiremock/wiremock-testcontain ers-go/tree/main/examples/quickstart
26. github.com/wiremock/wiremock-testcontainers-go
27. Is a Single Container Enough? - asking for a container CI/CD guy
29. Platforms Docker Compose
30. References • Testcontainers for Golang: https://golang.testcontainers.org/ • WireMock Demos: github.com/wiremock/wiremock-testcontainers-go/tree/main/examples
31. Takeaways 31 • 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!
33. It’s [always] a great time to contribute! testcontainers.org/contributing wiremock.org/participate 33
34. Learn More at Oleg Nenashev - Workshop Mocks as Code. Modeling AWS service providers with Testcontainers, WireMock and Localstack LocalStack
35. KCD Suisse Romande Dec 2025, Genève, CERN
36. Async Q&A: Testcontainers Slack speakerdeck.com/onenashev
37. GitHub: oleg-nenashev Twitter: @oleg_nenashev Questions? Gradle Community Slack, #developer-productivity-engineering Testcontainers Slack