Better Testing with Testcontainers

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1 Better Testing With Testcontainers

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2 Gerrit Meier ● Software Engineer at Neo4j ● Team Spring Data Neo4j and Neo4j OGM ●

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Software Testing

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Software Testing Integration testing

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Integration testing “Testing our application interacting with an external system.” -me

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Common setups 6

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Common setups 7 Embedded

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Common setups 8 Embedded Local instance

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Common setups 9 Embedded Local instance Remote instance

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Common setups 10 Embedded Local instance Remote instance Docker

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11 Embedded

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12 Pros - Clean instance - Portable test suite - No side-effects from the outside Embedded

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13 Cons Pros - Dependency version - JVM version - Non-existing network - Memory allocation - Post-mortem debugging - Clean instance - Portable test suite - No side-effects from the outside Embedded

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14 Local instance

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15 Pros - Separation of application and database - Network - No version conflicts - Post-mortem debugging Local instance

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16 Cons Pros - Custom configuration - Setup needed for colleagues and CI - Lifecycle control on CI - Separation of application and database - Network - No version conflicts - Post-mortem debugging Local instance

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17 Remote instance a.k.a. the “Test instance”

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18 Pros - One time setup - Always on - No lifecycle management needed Remote instance a.k.a. the “Test instance”

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19 Cons Pros - Shared database state - Conflicting tests - Unexpected test failures - Post-mortem debugging - One time setup - Always on - No lifecycle management needed Remote instance a.k.a. the “Test instance”

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20 Docker

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21 Pros - Orchestration within test setup - Isolated testing Docker

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22 Cons Pros - Java API “command line”-style - Ready(?) - Orchestration within test setup - Isolated testing Docker

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Testcontainers - Fluent wrapper around Docker API - Support for a lot of systems out-of-the-box - Aware of readiness(!) - Seamless integration with JUnit (and Spock) - Networks of multiple containers - Copy data for testing

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24 Spring Boot Spring Data Neo4j JUnit 5

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25 MaterialIT.java @SpringBootTest class MaterialIT { private final MaterialRepository repository; private final Neo4jClient neo4jClient; @Autowired MaterialIT(MaterialRepository repository, Neo4jClient neo4jClient) { this.repository = repository; this.neo4jClient = neo4jClient; } }

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26 pom.xml Add Testcontainers org.testcontainers junit-jupiter 1.17.6 test

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27 MaterialIT.java @SpringBootTest class MaterialIT { static GenericContainer> container = new GenericContainer<>("neo4j:5") .withExposedPorts(7687) .withEnv("NEO4J_AUTH", "neo4j/verysecret"); }

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28 MaterialIT.java @SpringBootTest class MaterialIT { static GenericContainer> container = new GenericContainer<>("neo4j:5") .withExposedPorts(7687) .withEnv("NEO4J_AUTH", "neo4j/verysecret"); @BeforeAll static void startDatabase() { container.start(); } }

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29 MaterialIT #testingProperties @DynamicPropertySource static void testingProperties( DynamicPropertyRegistry registry) { registry.add("spring.neo4j.uri", () -> "neo4j://" + container.getHost() + ":" + container.getMappedPort(7687)); registry.add("spring.neo4j.authentication.username", () -> "neo4j"); registry.add("spring.neo4j.authentication.password", () -> "verysecret"); }

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30 MaterialIT.java @SpringBootTest @Testcontainers class MaterialIT { @Container static GenericContainer> container = new GenericContainer<>("neo4j:5") .withExposedPorts(7687) .withEnv("NEO4J_AUTH", "neo4j/verysecret"); }

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Testcontainers Neo4j - Neo4j readiness aware - Simplified env parameters for configuration - Exposes Bolt and HTTP port as default - Neo4j specific API - Admin user setup - Connection related information - Neo4j Labs Plugin activation

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32 pom.xml Add Testcontainers org.testcontainers neo4j 1.17.6 test

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33 MaterialIT.java @SpringBootTest @Testcontainers class MaterialIT { @Container static Neo4jContainer> container = new Neo4jContainer<>("neo4j:5") .withAdminPassword("verysecret") }

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34 MaterialIT #testingProperties @DynamicPropertySource static void testingProperties( DynamicPropertyRegistry registry) { registry.add("spring.neo4j.uri", container::getBoltUrl); registry.add("spring.neo4j.authentication.username", () -> "neo4j"); registry.add("spring.neo4j.authentication.password", container::getAdminPassword); }

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35 MaterialIT #pluginCall void pluginCall() { String apocVersion = neo4jClient .query("RETURN apoc.version()") .fetchAs(String.class) .one().get(); Assertions.assertThat(apocVersion) .isEqualTo("5.1.0"); }

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36 MaterialIT #pluginCall void pluginCall() { String apocVersion = neo4jClient .query("RETURN apoc.version()") .fetchAs(String.class) .one().get(); Assertions.assertThat(apocVersion) .isEqualTo("5.1.0"); } Unknown function 'apoc.version'

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37 MaterialIT.java @SpringBootTest @Testcontainers class MaterialIT { @Container static Neo4jContainer> container = new Neo4jContainer<>("neo4j:5") .withAdminPassword("verysecret") .withLabsPlugins(Neo4jLabsPlugin.APOC) }

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38 MaterialIT #pluginCall void pluginCall() { String apocVersion = neo4jClient .query("RETURN apoc.version()") .fetchAs(String.class) .one().get(); Assertions.assertThat(apocVersion) .isEqualTo("5.1.0"); }

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39 MaterialIT #pluginCall void pluginCall() { String apocVersion = neo4jClient .query("RETURN apoc.version()") .fetchAs(String.class) .one().get(); Assertions.assertThat(apocVersion) .isEqualTo("5.1.0"); }

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Performance (experimental) Feature: Reusable Testcontainers

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Performance (experimental) Feature: Reusable Testcontainers Neo4jContainer> container = new Neo4jContainer<>("neo4j:5") .withAdminPassword("verysecret") .withReuse(true)

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Performance (experimental) Feature: Reusable Testcontainers testcontainers.reuse.enable=true ~/.testcontainers.properties Neo4jContainer> container = new Neo4jContainer<>("neo4j:5") .withAdminPassword("verysecret") .withReuse(true)

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Conclusion ● Reproducible and portable tests ● No manual lifecycle management (JUnit extension) ● For more performance: reusable containers ● Covers more than just Neo4j ● Create Test Matrix with ease

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44 Create data Neo4j-Migrations Neo4j Migrations: The Lean Way of Applying Database Refactorings to Neo4j Michael Simons 15:40 (UTC) 16:40 (CET)

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45 ● Testcontainers: https://www.testcontainers.org/ ● Reusable Testcontainers: ● https://foojay.io/today/faster-integration-tests- with-reusable-testcontainers/ ● me: @meistermeier(@mastodon.social) Thank you! ❤