Richtige Integrationstests mit Containern
A presentation at Magdeburger Developer Days in in Magdeburg, Germany by Philipp Krenn
Richtige Integrationstests mit Containern Philipp Krenn @xeraa
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(“_doc”, 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 Generic
Dependency @ClassRule public static GenericContainer redis = new GenericContainer(“redis:5.0.5”) .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
What’s in docker ps -a
Docker for Mac API: socat Linux: Multipurpose relay (SOcket CAT) https://github.com/alpine-docker/socat
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)
! IDE support, customization, custom lifecycle ! Hacky configuration
Testcontainers Custom
ElasticsearchContainer https://www.testcontainers.org/modules/elasticsearch/
Demo
More languages Scala, Go, .net , Python , JavaScript , Rust * * * Early development * *
Selenium 2 / Webdriver VNC screen recording
! IDE support, customization, custom lifecycle ! Custom integration
Inside Containers
Wormhole Pattern
$ 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
Wie testet man mit Datenbanken?
- Mocking ist keine Option, da man das tatsächliche System testen möchte.
- In-Memory-Datenbanken, wie H2 oder HSQLDB, haben kleinere und größere Unterschiede und nicht alle Datenspeicher haben In-Memory-Geschwister.
- Verwendung und Test-Parallelisierung des eigentlichen Datenspeichers ist alles andere als ideal.
Was ist also die Lösung? Es gibt zwei saubere Ansätze basierend auf Containern: Testcontainers und das Docker-Maven-Plugin. Aus den Tests können leichtgewichtige, wegwerfbare Instanz des jeweiligen Datenbanksystems gestartet werden. Dieser Vortrag zeigt ein praktisches Beispiel vor. Außerdem sehen wir uns das Testcontainer Modul für Elasticsearch an.
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.
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