Real Integration Tests with TestContainers
A presentation at ContainerDays in in Hamburg, Germany by Philipp Krenn
Philipp Krenn @xeraa Real Integrat- 444 ion Tests with
Infrastructure | Developer !
Integration Tests
But the unit tests passed, so... https://twitter.com/Aaronius/status/ 933497253347463168
Mocking
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
de.flapdoodle. embed.process https://github.com/flapdoodle-oss/ de.flapdoodle.embed.process
...will provide a platform neutral way for running processes in unittests.
→ MongoDB de.flapdoodle.embed.mongo → Redis de.flapdoodle.de.embed.redis → Memcached de.flapdoodle.embed.memcached → PostgreSQL ru.yandex.qatools.embed → MySQL com.wix.mysql → Consul com.github.golovnin.embedded.consul → Vault com.github.golovnin.embedded.vault → InfluxDB io.apisense.embed.influx
Build Tool
docker-maven-plugin http://dmp.fabric8.io
Build 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/
! Plain or custom Docker image ! One instance for all tests
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-java- module-elasticsearch https://github.com/dadoonet/testcontainers-java-module- elasticsearch
Demo
Todo Set (randomized) port
! Container per test Or reuse in static block ! Custom integration
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 4444 @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 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.
Video
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
Buzz and feedback
Here’s what was said about this presentation on social media.
