Containers for Real Integration Tests
A presentation at Percona Live Europe in in Frankfurt, Germany by Philipp Krenn
Developer
Tests
But the unit tests passed, so... https://twitter.com/Aaronius/status/ 933497253347463168
Integration Tests
Mocks
Mockito, EasyMock, JMock,...
Ich mock mir die Welt widdewidde wie sie mir gefällt
https://www.monkeyuser.com/2018/ happy-flow/
! Unit tests, systems not under your control ! Test real datastore
In-Memory
H2, HSQLDB, Apache Derby,...
Embedded Elasticsearch unsupported in 5.0+ https://www.elastic.co/blog/elasticsearch-the-server
! Often good enough ! Test real datastore, supported systems
Actual Datastore
Local installation Docker container Cloud
Demo
! "Good old approach" ! External dependency, parallelization
Embedded
embedded-elasticsearch https://github.com/allegro/embedded-elasticsearch
Demo
Customization & Mappings .withPlugin("analysis-stempel") .withIndex("cars", IndexSettings.builder() .withType("car", getSystemResourceAsStream("car-mapping.json"))
! IDE support, customization, custom lifecycle ! Custom integration
More embedded datastores https://github.com/flapdoodle-oss/ de.flapdoodle.embed.process
Build Tool
docker-maven-plugin http://dmp.fabric8.io
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>
Build a custom image: docker:build Run container: docker:start docker:stop
Demo
maven-failsafe-plugin https://maven.apache.org/surefire/maven-failsafe-plugin/
! Standard or custom Docker image ! One instance for all tests, no IDE support
Testcontainers
Dependency @ClassRule public static GenericContainer redis = new GenericContainer("redis:3.0.2") .withExposedPorts(6379);
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));
Demo
! IDE support, customization, custom lifecycle ! Hacky configuration
Cleanup: Moby Ryuk https://github.com/testcontainers/moby-ryuk
[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)
testcontainers-javamodule-elasticsearch https://github.com/dadoonet/testcontainers-java-moduleelasticsearch
Work in progress https://github.com/testcontainers/testcontainers-java/pull/ 826 Set (randomized) port
Demo
More languages Scala, Go, .net , Python , JavaScript , Rust * * * Early development * *
Selenium 2 / Webdriver VNC screen recording
! IDE support, customization, custom lifecycle ! Custom integration
Docker in Docker Or sidecar
$ 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
Conclusion
Why Integration Tests
Why not Mocking In-Memory Actual Datastore
How Embedded Build Tool Testcontainers
Code https://github.com/xeraa/integration-test-demo
Questions? Philipp Krenn @xeraa
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 are some very neat solutions based on containers, namely the Docker-Maven-Plugin and TestContainers. From your tests you can start a lightweight, throwaway instance of your datastore and this talk will walk you through how to do that.
Resources
The following resources were mentioned during the presentation or are useful additional information.
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GitHub: Demo Code
Demoing multiple approaches of integration tests with Elasticsearch.
