TestContainers: JEEConf 2017

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TestContainers Integration testing without the hassle Sergei @bsideup Egorov

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About me • Site Reliability Engineer at • Before: ZeroTurnaround, TransferWise, etc… • TestContainers’ co-maintainer • In love with Docker since 2013 @bsideup

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Integration testing Why it matters?

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Verify how your software product will behave in real-world conditions

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Isolated from other system components to avoid false negatives

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Real: databases, ﬁle systems, network interfaces, …

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Grey box testing - we know some inner details, but mostly use public APIs

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Unit testing • Simulation tests are green, yay! • Everything is mocked • DB is written by others, why should I test it?

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Integration testing https://commons.wikimedia.org/wiki/File:Cd4007.jpg • Jeez, how did it passed the Unit testing? • Is it a smoke? @#$%! YES IT IS! • Who knew that 100w soldering gun was a bit too powerful for it?

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System testing https://commons.wikimedia.org/wiki/File:UART_8250_Microchip.jpg • Takes a lot of time to solder • “Oh no, the power bus is too far away from my microchip!” • Interference between the components

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Production

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Integration testing Real-world, but isolated testing Spot the issues before the real environment Can be run during the development You have to start real databases Should be cross-platform Slower than Unit testing Pros Cons

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Obvious solution

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Abstraction layer

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CI friendly

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Cross-platform

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Docker Compose FTW! redis:  image: redis  ports:  - "6379:6379"  postgres:  image: postgres  ports:  - "5432:5432"  elasticsearch:  image: elasticsearch:5.0.0  ports:  - "9200:9200" 

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But…

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No ports randomization redis:  image: redis  ports:  - "6379:6379"  postgres:  image: postgres  ports:  - "5432:5432"  elasticsearch:  image: elasticsearch:5.0.0  ports:  - "9200:9200" 

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Fighting with Docker environment

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There is no place like

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There is no place like Except Docker Machine

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Can we improve that?

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Remove the database

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Remove the database

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TestContainers • http://github.com/testcontainers/testcontainers-java • Wraps docker-java library • Docker environment discovery (Win, Mac, Linux) • Will start docker-machine if it’s not started yet • Containers cleanup on JVM shutdown

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As simple as PostgreSQLContainer postgresql = new PostgreSQLContainer()    GenericContainer redis = new GenericContainer("redis:3")  .withExposedPorts(6379)

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Users

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Use case #1: testing of microservices • REST service • Java, Spring Boot • Redis and PostgreSQL • Calls some other micro-services

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@RunWith(SpringRunner.class) @SpringBootTest(webEnvironment = RANDOM_PORT) @ContextConﬁguration(initializers = Initializer.class) public abstract class AbstractIntegrationTest { @ClassRule public static PostgreSQLContainer postgreSql = new PostgreSQLContainer(); @ClassRule public static GenericContainer redis = new GenericContainer("redis:3.0.6") .withExposedPorts(6379); @ClassRule public static MockServerContainer mockServer = new MockServerContainer(); }

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public class MockServerContainer> extends GenericContainer { public MockServerContainer() { super("jamesdbloom/mockserver:latest"); addExposedPorts(8080); } private MockServerClient client; @Override protected void containerIsStarted(InspectContainerResponse containerInfo) { super.containerIsStarted(containerInfo); client = new MockServerClient(getContainerIpAddress(), getMappedPort(getExposedPorts().get(0))); } }

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Demo

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Use case #2: Docker as Selenium driver • Selenium/Selenide tests • No need to install Chrome/Firefox/etc • CI friendly

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@Rule public BrowserWebDriverContainer chrome = new BrowserWebDriverContainer() .withDesiredCapabilities(DesiredCapabilities.chrome()) .withRecordingMode(RECORD_ALL, new File("target"));

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@Rule public BrowserWebDriverContainer chrome = new BrowserWebDriverContainer() .withDesiredCapabilities(DesiredCapabilities.chrome()) .withRecordingMode(RECORD_ALL, new File("target")); RemoteWebDriver driver = chrome.getWebDriver(); driver.get("https://wikipedia.org"); WebElement searchInput = driver.findElementByName("search"); searchInput.sendKeys("Rick Astley"); searchInput.submit(); WebElement otherPage = driver.findElementByLinkText("Rickrolling"); otherPage.click(); boolean expectedTextFound = driver.findElementsByCssSelector("p") .stream() .anyMatch(element -> element.getText().contains("meme")); assertTrue("The word 'meme' is found on a page about rickrolling", expectedTextFound);

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Demo

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• http://testcontainers.org • testcontainers/testcontainers-java-examples • Integration testing is a must • Docker works great for testing • Uniﬁed env for Dev and CI