Real Integration Tests with TestContainers

How are you doing integration tests with your datastore?

* Mocking is not an option since you want to test the actual system.
* There are some in-memory implementations, like H2 or HSQLDB for relational databases, but there are still subtle differences to your production system and not all datastores have in-memory cousins.
* Using the actual datastore in your tests is possible, but managing it, running tests in parallel,... is far from ideal.

So what is the solution? There is a very neat solution based on containers: TestContainers. From your tests you can start a lightweight, throwaway instance of your datastore and this talk will walk you through on how to do that as well as alternatives with docker-maven-plugin.

Transcript

1. Containers for Real Integration Tests Philipp Krenn̴̴̴@xeraa
2. Developer
3. Tests
6. But the unit tests passed, so... https://twitter.com/Aaronius/status/ 933497253347463168
12. Integration Tests
13. Mocks
14. Mockito, EasyMock, JMock,...
16. Ich mock mir die Welt widdewidde wie sie mir gefällt
17. https://www.monkeyuser.com/2018/ happy-flow/
18. ! Unit tests, systems not under your control ! Test real datastore
19. In-Memory
20. H2, HSQLDB, Apache Derby,...
22. Embedded Elasticsearch unsupported in 5.0+ https://www.elastic.co/blog/elasticsearch-the-server
23. ! Often good enough ! Test real datastore, supported systems
24. Actual Datastore
25. Local installation Docker container Cloud
26. Demo
27. ! "Good old approach" ! External dependency, parallelization
28. Embedded
29. embedded-elasticsearch https://github.com/allegro/embedded-elasticsearch
30. Demo
31. Customization & Mappings .withPlugin("analysis-stempel") .withIndex("cars", IndexSettings.builder() .withType("car", getSystemResourceAsStream("car-mapping.json"))
32. ! IDE support, customization, custom lifecycle ! Custom integration
33. More embedded datastores https://github.com/flapdoodle-oss/ de.flapdoodle.embed.process
34. Build Tool
35. docker-maven-plugin http://dmp.fabric8.io
36. Dockerfile or Docker assembly <build> <from>java:8</from> <assembly> <descriptor>docker-assembly.xml</descriptor> </assembly> <cmd> <shell>java -jar /maven/service.jar</shell> </cmd> </build>
37. Build a custom image: docker:build Run container: docker:start docker:stop
38. Demo
39. maven-failsafe-plugin https://maven.apache.org/surefire/maven-failsafe-plugin/
40. ! Standard or custom Docker image ! One instance for all tests, no IDE support
41. Testcontainers
42. Dependency @ClassRule public static GenericContainer redis = new GenericContainer("redis:3.0.2") .withExposedPorts(6379);
43. Docker Compose integration @ClassRule public static DockerComposeContainer environment = new DockerComposeContainer(new File("src/test/resources/compose.yml")) .withExposedService("elasticsearch_1", ELASTICSEARCH_PORT, Wait.forHttp("/").forStatusCode(200));
44. Demo
45. ! IDE support, customization, custom lifecycle ! Hacky configuration
46. Cleanup: Moby Ryuk https://github.com/testcontainers/moby-ryuk
47. [Ryuk] drops a Death Note, a notebook that allows the user to kill anyone simply by knowing their name and face https://en.wikipedia.org/wiki/Ryuk_(Death_Note)
49. ElasticsearchContainer https://www.testcontainers.org/modules/elasticsearch/
50. Demo
51. More languages Scala, Go, .net*, Python*, JavaScript*, Rust* * Early development
52. Selenium 2 / Webdriver VNC screen recording
53. ! IDE support, customization, custom lifecycle ! Custom integration
55. Docker in Docker Or sidecar
56. $ docker run -it --rm -v $PWD:$PWD -w $PWD -v /var/run/docker.sock:/var/run/docker.sock maven:3 mvn --projects parent,4_testcontainers-custom test $ docker ps -a
57. Conclusion
58. Why Integration Tests
59. Why not Mocking In-Memory Actual Datastore
60. How Embedded Build Tool Testcontainers
61. Code https://github.com/xeraa/integration-test-demo
62. Questions? Philipp Krenn̴̴̴̴@xeraa