Testcontainers for Real Integration Tests

A presentation at SwanseaCon in September 2018 in Swansea, UK by Philipp Krenn

Philipp Krenn @xeraa Real Integrat- ion Tests with

Developer

Tests

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

Ok — we need Interation Tests

Mocks

Mockito, EasyMock, JMock,...

Ich mock mir die Welt widdewidde wie sie mir gefällt

! 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

In-Process

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

Build a custom image: docker:build Run container: docker:start & docker:stop

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>

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

Testcontainers is a Java library that supports JUnit tests, providing lightweight, throwaway instances of common databases [...] that can run in a Docker container.

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

testcontainers-javamodule-elasticsearch https://github.com/dadoonet/testcontainers-java-moduleelasticsearch

Work in Progress https://github.com/testcontainers/testcontainers-java/pull/ 826

Demo

Todo Set (randomized) port

! IDE support, customization, custom lifecycle ! Custom integration

Containerized CI? Sidecar Or embedded approach

Conclusion

Why Integration Tests

Why not Mocking In-Memory Actual Datastore

How In-Process Build Tool Testcontainers

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

Questions? Philipp Krenn @xeraa

Philipp Krenn
@xeraa

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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 a practical example with Elasticsearch's Testcontainer after covering the issues of other approaches first. We are also discussing the general approach of Testcontainers and how they are now widely available for various datastores.

Resources

The following resources were mentioned during the presentation or are useful additional information.

GitHub: Demo Code

Demoing multiple approaches of integration tests with Elasticsearch