1. Better integration tests for
Kafka applications with
Testcontainers

2. Oleg Šelajev
Developer relations

5. Tests are essential

6. Unit tests
Integration
tests
e2e

8. Unit tests
Integration
tests
e2e

9. Timeline Local DBs
Integration Testing transformation
over the years (i)
Mocking VMs (Vagrant)

10. Timeline
Integration Testing transformation
over the years (ii)
Docker Compose
Docker Docker API

11. Common approaches to integration testing
In Integration tests we are interested in verifying the behavior and interactions of
multiple components.
For this purpose we can use:
● Shared instances
● Local installations
● In memory solutions
○ Mock server (Wiremock, Loki…)
○ In-memory service (h2, hsql...)
● Docker Compose

12. Testcontainers-java
• Created 7 years ago (Docker is 8 years old)
• github.com/testcontainers/testcontainers-java
• Uses docker-java API
• Integrates with frameworks, like Spring, JUnit
• Works with anything that runs in a Docker container

13. Growing ecosystem of modules

14. testcontainers.com/modules

15. testcontainers.com/modules

16. Why are Testcontainers - 🏆🏆🏆
●Flexible lifecycle API: isolation vs convenience
●Capable of abstractions
○ modules
●Readiness control
●Complex network topologies
●Randomized ports mapping
●Everything is dynamic allowing parallelisation
●Self-contained tests: feels like a unit, reliable like integration

17. 🏆🏆🏆
Feels like a unit, reliable like integration

18. Parallelization
●Surefire plugin
○ parallel=classes
○ forkCount=N
○ reuseForks=true
●Showcase
○ github.com/testcontainers/testcontainers-showcase
https://maven.apache.org/surefire/maven-surefire-plugin/examples/fork-options-and-parallel-execution.html

19. ●Using Docker-in-Docker (DinD)
●Testcontainers Cloud setup
●Parallelisation
https://www.atomicjar.com/2023/01/running-testcontainers-tests-on-gitlab-ci/

20. start.spring.io has it :)

21. Local development environment with SpringBoot 3.1
https://docs.spring.io/spring-boot/docs/3.1.0-SNAPSHOT/reference/htmlsingle/#features.testing.testcontainers.at-development-time

24. What’s next?
— github.com/testcontainers/testcontainers-java
— testcontainers.org
— slack.testcontainers.org