Restoring sanity to integration & functional testing with TestContainers

Many organizations struggle with maintaining tests that require more complex setup procedures. As a result, tests become flaky, unreliable and require manual intervention. In a world of "automate all the things" this is very counterproductive and unnecessarily costs organizations time and money.

In this lightning talk, we'll have a look at setting up and running integration & functional tests with the help of the open source library TestContainers. You will learn how to stand up lightweight, disposable Docker instances running your application as reliable test fixtures.

Transcript

1. Restoring sanity to integra-on &
   func-onal tes-ng with TestContainers
   Benjamin Muschko
   

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2. AUTOMATED
   ASCENT
   bmuschko
   bmuschko
   bmuschko.com
   About the speaker
   automatedascent.com
   

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3. Who writes
   integra-on tes-ng?
   

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4. 2 unit tests, 0 integra-on tests
   

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5. Reproducible
   environment
   

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6. Slow startup
   time
   

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7. Isolated &
   cross-platform
   

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8. There must
   be a better
   way!
   

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9. 
   The obvious choice
   

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10. Java library for managing
    Docker container in JUnit tests
    

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11. Docker Engine communica-on
    

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12. Docker environment discovery
    

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13. Container cleanup
    

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14. Crea-ng a database container
    @Testcontainers

    public class DatabaseIntegrationTest {

    

    @Container

    public static PostgreSQLContainer postgreSqlContainer =
    new PostgreSQLContainer("postgres:9.6.10-alpine")

    .withUsername("username")

    .withPassword("pwd")

    .withDatabaseName("todo");

    }
    

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15. Configuring Spring applica-on context
    static class Initializer implements↵
    ApplicationContextInitializer {

    @Override

    public void initialize(ConfigurableApplicationContext↵
    configurableApplicationContext) {

    TestPropertyValues.of(

    "spring.datasource.url=" + container.getJdbcUrl(),

    "spring.datasource.username=" + container.getUsername(),

    "spring.datasource.password=" + container.getPassword(),

    "spring.datasource.driver-class-name=org.postgresql.Driver",

    "spring.jpa.generate-ddl=true"

    ).applyTo(configurableApplicationContext.getEnvironment());

    }

    }
    

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16. Star-ng a generic container
    @Testcontainers

    public class ApplicationIntegrationTest {

    

    @Container

    public static GenericContainer appContainer = createAppContainer();

    

    private static GenericContainer createAppContainer() {

    return new GenericContainer(buildImageDockerfile())

    .withExposedPorts(8080)

    .withEnv("SPRING_PROFILES_ACTIVE", "dev")

    .waitingFor(Wait.forHttp("/actuator/health")

    .forStatusCode(200));

    }

    

    private static ImageFromDockerfile buildImageDockerfile() {

    return new ImageFromDockerfile()

    .withFileFromFile(ARCHIVE_NAME, new File(DISTRIBUTION_DIR, ARCHIVE_NAME))

    .withDockerfileFromBuilder(builder -> builder

    .from("openjdk:jre-alpine")

    .copy(ARCHIVE_NAME, "/app/" + ARCHIVE_NAME)

    .entryPoint("java", "-jar", "/app/" + ARCHIVE_NAME)

    .build());

    }

    }
    

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17. Accessing container IP & ports
    private URL buildEndpointUrl(String context) {

    StringBuilder url = new StringBuilder();

    url.append("http://");

    url.append(appContainer.getContainerIpAddress());

    url.append(":");

    url.append(appContainer.getFirstMappedPort());

    url.append(context);

    

    try {

    return new URL(url.toString());

    } catch (MalformedURLException e) {

    throw new RuntimeException("Invalid URL", e);

    }

    }
    

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18. Managing a set of services
    @Testcontainers

    public class DockerComposeIntegrationTest {

    

    private final static String POSTGRES_SERVICE_NAME = "database_1";

    private final static int POSTGRES_SERVICE_PORT = 5432;

    

    @Container

    public static DockerComposeContainer environment =↵
    createComposeContainer();

    

    private static DockerComposeContainer createComposeContainer() {

    return new DockerComposeContainer(new File(PROJECT_DIR,↵
    "src/test/resources/compose-test.yml"))

    .withExposedService(POSTGRES_SERVICE_NAME,
    POSTGRES_SERVICE_PORT);

    }

    }
    

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19. Sample Docker Compose file
    database:

    image: "postgres:9.6.10-alpine"

    environment:

    - POSTGRES_USER=postgres

    - POSTGRES_PASSWORD=postgres

    - POSTGRES_DB=todo

    elasticsearch:

    image: "elasticsearch"
    

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20. Retrieving service host & port
    private static String getPostgresServiceUrl() {

    String postgresHost =↵
    environment.getServiceHost(POSTGRES_SERVICE_NAME,↵
    POSTGRES_SERVICE_PORT);

    Integer postgresPort =↵
    environment.getServicePort(POSTGRES_SERVICE_NAME,↵
    POSTGRES_SERVICE_PORT);

    StringBuilder postgresServiceUrl = new StringBuilder();

    postgresServiceUrl.append("jdbc:postgresql://");

    postgresServiceUrl.append(postgresHost);

    postgresServiceUrl.append(":");

    postgresServiceUrl.append(postgresPort);

    postgresServiceUrl.append("/todo");

    return postgresServiceUrl.toString();

    }
    

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21. Demo Time!
    hNps:/
    /github.com/bmuschko/testcontainers-demo
    

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22. Thanks!
    Please ask ques-ons.
    

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