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
   

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2. Developer
   

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3. Tests
   

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6. But the unit tests
   passed, so...
   https://twitter.com/Aaronius/status/
   933497253347463168
   

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12. Integration
    Tests
    

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13. Mocks
    

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14. Mockito, EasyMock,
    JMock,...
    

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16. Ich mock mir die Welt
    widdewidde wie sie mir
    gefällt
    

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17. https://www.monkeyuser.com/2018/
    happy-flow/
    

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18. !
    Unit tests, systems not
    under your control
    !
    Test real datastore
    

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19. In-Memory
    

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20. H2, HSQLDB, Apache
    Derby,...
    

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22. Embedded Elasticsearch
    unsupported in 5.0+
    https://www.elastic.co/blog/elasticsearch-the-server
    

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23. !
    Often good enough
    !
    Test real datastore,
    supported systems
    

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24. Actual
    Datastore
    

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25. Local installation
    Docker container
    Cloud
    

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26. Demo
    

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27. !
    "Good old approach"
    !
    External dependency,
    parallelization
    

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28. Embedded
    

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29. embedded-elasticsearch
    https://github.com/allegro/embedded-elasticsearch
    

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30. Demo
    

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31. Customization & Mappings
    .withPlugin("analysis-stempel")
    .withIndex("cars", IndexSettings.builder()
    .withType("car", getSystemResourceAsStream("car-mapping.json"))
    

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32. !
    IDE support,
    customization, custom
    lifecycle
    !
    Custom integration
    

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33. More embedded
    datastores
    https://github.com/flapdoodle-oss/
    de.flapdoodle.embed.process
    

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34. Build Tool
    

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35. docker-maven-plugin
    http://dmp.fabric8.io
    

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36. Dockerfile or Docker assembly
    
    java:8
    
    docker-assembly.xml
    
    
    java -jar /maven/service.jar
    
    
    

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37. Build a custom image:
    docker:build
    Run container:
    docker:start
    docker:stop
    

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38. Demo
    

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39. maven-failsafe-plugin
    https://maven.apache.org/surefire/maven-failsafe-plugin/
    

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40. !
    Standard or custom
    Docker image
    !
    One instance for all
    tests, no IDE support
    

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41. Testcontainers
    

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42. Dependency
    @ClassRule
    public static GenericContainer redis =
    new GenericContainer("redis:3.0.2")
    .withExposedPorts(6379);
    

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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));
    

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44. Demo
    

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45. !
    IDE support,
    customization, custom
    lifecycle
    !
    Hacky configuration
    

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46. Cleanup: Moby Ryuk
    https://github.com/testcontainers/moby-ryuk
    

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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)
    

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49. ElasticsearchContainer
    https://www.testcontainers.org/modules/elasticsearch/
    

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50. Demo
    

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51. More languages
    Scala, Go, .net*, Python*, JavaScript*, Rust*
    * Early development
    

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52. Selenium 2 / Webdriver
    VNC screen recording
    

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53. !
    IDE support,
    customization, custom
    lifecycle
    !
    Custom integration
    

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55. Docker in Docker
    Or sidecar
    

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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
    

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57. Conclusion
    

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58. Why
    Integration Tests
    

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59. Why not
    Mocking
    In-Memory
    Actual Datastore
    

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60. How
    Embedded
    Build Tool
    Testcontainers
    

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61. Code
    https://github.com/xeraa/integration-test-demo
    

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62. Questions?
    Philipp Krenn̴̴̴̴@xeraa
    

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