TestContainers + JUnit 5 = elegant integration and e2e tests for microservices

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TestContainers + JUnit 5 = elegant integration and e2e tests for microservices Nikolay Kuznetsov @nikolayk812 TESTING UNITED Vienna, 7 November 2019

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About me ● Go developer at Zalando Helsinki ● Java developer at Infobip, DevExperts ● C developer at Samsung, Motorola

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My testing experience ● Unit, integration and end-to-end automated tests development ● Various organizational structures ○ Separate QA teams ○ QA engineers in a dev team ○ No QA teams/engineers at all

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Key points ● Targeting automated testing ● Examples and demos in Java: TestContainers-Java, JUnit 5, Spring Boot ● Principles are language-agnostic

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Why integration testing?

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2 unit tests, 0 integration tests

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Tests trade-oﬀs

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Basic integration test

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Integration testing evolution ● In-memory mocking ● Local DBs ● Vagrant ● Docker, Docker Compose ● Docker API

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Docker architecture

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How to start a container for test? ● Shell scripts ● Maven plugin ● Docker Compose ● Docker API ● MiniKube, Kubernetes

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Shell scripts

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Maven plugin github.com/fabric8io/docker-maven-plugin

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Docker Compose

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Docker API

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TestContainers ﬂavors

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TestContainers Java ● github.com/testcontainers/testcontainers-java ● Wraps docker-java library ● Docker environment autodiscovery ● Host port randomization ● Containers clean up on JVM shutdown ● Readiness waiting strategies

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As simple as var redis = new GenericContainer("redis:5.0.5") .withExposedPorts(6379); var postgres = new PostgreSQLContainer();

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Docker environment autodiscovery

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Host port randomization ● Prevents port conflicts ● Enables parallel CI builds ● API to get an actual host port

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Containers cleanup github.com/testcontainers/moby-ryuk

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Readiness waiting strategies ● Host port ● HTTP status/body ● Log message ● Docker healthcheck ● Combination of above ● Custom

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Demo setup User Service

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Demo scenario User Service INSERT INTO SELECT FROM

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Demo github.com/nikolayk812/tu-tc-demo

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Demo recap ● JUnit 5 integration via Extension API ○ @TestContainers / @Container ● TestContainers Modules ○ 14 databases ○ Kafka, MockServer, LocalStack, ToxiProxy, etc

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JUnit 5 Extensions ● Customizable extension points: ○ Life-cycle phases ○ Parameter resolution ○ Conditional execution, etc ● Extension logic registered with @ExtendsWith

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github.com/nikolayk812/tu-tc-demo Demo-2: setup User Service

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Demo-2: scenario User Service POST /users GET /user/

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Demo-2: Docker network User Service user-alias: 8083 postgres-alias: 5432 localhost: 32812

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Demo 2 github.com/nikolayk812/tu-tc-demo

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Demo-2: recap ● Docker network and alias

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Why end-to-end testing? ● Business flows across multiple services ● Regression, when ○ + new service ○ - legacy service

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Testing/staging deployed cluster Spring Cloud Kubernetes

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Testing against a deployed cluster ● Deploy a new service version to the cluster? ● Unexpected versions of dependent services ● Unexpected database states ○ Care to clear after the test? ● Parallel CI builds?

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On-demand cluster for E2E tests + Locally and at CI machines + Control over dependent services versions - Time to start all containers - Resources: memory and CPU How to do it?

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Kubernetes for E2E tests?

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Kubernetes for E2E tests - YAGNI TestContainers + Docker network!

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E2E test setup User Service Item Service

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Takeaways ● https://testcontainers.org ● Balance between flexibility, speed and features ● Works on Mac, Linux, Windows

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QUESTIONS ?