Integration testing with TestСontainers and JUnit 5

Transcript

1. Integration testing with TestСontainers and JUnit 5 Nikolay Kuznetsov @nikolayk812 Helsinki JUG Zalando 9 December 2019
2. About me • Go developer at Zalando Wardrobe • 6+ years of Java experience • Conference speaker: ◦ Voxxed Days Cluj, Container Days Hamburg • TestContainers-Go contributor
3. Why integration testing?
4. 2 unit tests, 0 integration tests
5. Basic integration test
6. Trade-offs Test Runtime
7. Integration testing evolution • In-memory mocking • Local DBs • Vagrant • Docker / Docker Compose • Docker API
8. Docker advantages • 100% compatible database • Same version as production • Empty or known state
9. Docker architecture
10. How to start a container for test? • Shell scripts • Maven plugin • Docker Compose • Docker API • MiniKube, Kubernetes
11. Shell scripts
12. Maven plugins github.com/fabric8io/docker-maven-plugin
13. Docker Compose
14. Docker API docs.docker.com/engine/api/latest
15. Exec example
17. TestContainers flavors
18. TestContainers Java • github.com/testcontainers/testcontainers-java • Wraps docker-java library • Docker environment discovery • Host port randomization • Containers clean up on JVM shutdown • Readiness waiting strategies
19. As simple as var redis = new GenericContainer("redis:5.0.6") .withExposedPorts(6379); var postgres = new PostgreSQLContainer();
20. Docker environment discovery
21. Talking to Docker via UDS • curl --unix-socket /var/run/docker.sock http:/localhost/containers/json • curl --unix-socket /var/run/docker.sock http:/localhost/networks
22. Host port randomization • To prevent port conflicts • Enables parallel builds • API to get a host port
23. Containers cleanup https://github.com/testcontainers/moby-ryuk
24. Waiting strategies • Host port • HTTP • Log message • Docker healthcheck • Combined / Custom
25. Host port waiting strategy • Default: at first exposed port with timeout of 60s • Both from outside and inside container
26. Internal port check
27. HTTP waiting strategy • Status & response body predicate
28. Demo setup User Service
29. Demo scenario User Service INSERT INTO SELECT FROM
30. Demo github.com/nikolayk812/hjug-tc-demo
31. Demo recap • JUnit 5 Extension API • TestContainer modules
32. JUnit 5 extension points • Life-cycle callbacks • Conditional execution • Parameter resolution • Exception handling
33. JUnit 5 extension logic • Implement interface(s) from o.j.j.api.extension package ◦ i.e. BeforeEachCallback, ExecutionCondition • Register with @ExtendsWith annotation • See @Testcontainers for reference
34. TestContainers modules • Preconfigured, optimized for testing • Wrappers on top of GenericContainer class • 14 databases • MockServer, LocalStack, Kafka, ToxiProxy
35. Demo-2: setup User Service
36. Demo-2: Docker network User Service user-alias: 8083 postgres-alias: 5432 localhost: 32812
37. Demo-2: scenario User Service POST /users GET /user/<id>
38. Demo-2 github.com/nikolayk812/hjug-tc-demo
39. Demo-2: recap • Docker network and alias
40. Why end-to-end testing? • Business flows across multiple services • Regression, when ◦ + new service ◦ - legacy service
41. Some cluster Spring Cloud Kubernetes
42. E2E strategies • Against a deployed cluster • Against on-demand in memory cluster
43. Deployed cluster cons • Replace a service with a newer version => instability • Temporary service name => non-discoverable • Unexpected databases states ◦ Care to clear data after the test?
44. On-demand cluster cons • Time to start all containers • Memory + CPU • How actually to create it?
45. On-demand Kubernetes for E2E?
46. YAGNI
47. On-demand cluster TC approach • Each service started by TestContainers • Shared Docker network • Functional tests • Unless testing Kubernetes manifests
48. E2E setup User Service Item Service
49. Hints • Host port forwarding Testcontainers.exposeHostPorts() • Fixed host port (for remote debugging) GenericContainer.addFixedExposedPort() • Reusable containers github.com/testcontainers/testcontainers-java/issues/781
50. Takeaways • https://testcontainers.org • Balance between flexibility, speed and features • Works on Mac, Linux, Windows • Great for integration tests! • Possible to use for end-to-end tests
51. Thank you! @nikolayk812 nikolayk812 nikolayk812