Test Jenkins Container with TestContainers Framework

As I create my Virtual Development Servers I asked myself how can I easily test, that it is working? As I put now my servers into containers via docker-compose I searched for a test framework, which supports this out of the box. I heard a lot about TestContainers in the past and again at Javaland 2022 conference last week, so I want to test now, if this will help me.

In the last blog Run your Development Server on Docker Desktop on Windows I created a Docker Desktop Container, which is running on Windows. Now I want to test this Container with automated tests.

As I want to use JUnit 5 as Wrapper I start with TestContainers JUnit 5 Quickstart Documentation.

So I create a fresh pom.xml and added the required dependencies.

    <dependency>
      <groupId>org.junit.jupiter</groupId>
      <artifactId>junit-jupiter</artifactId>
      <version>5.11.3</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.testcontainers</groupId>
      <artifactId>testcontainers</artifactId>
      <version>1.20.4</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.testcontainers</groupId>
      <artifactId>junit-jupiter</artifactId>
      <version>1.20.4</version>
      <scope>test</scope>
    </dependency>

Then I create my test class.

@Testcontainers
@DisplayName("Jenkins")
@DisplayNameGeneration(DisplayNameGenerator.ReplaceUnderscores.class)
class TestJenkins {

  public static final int JENKINS_PORT = 8080;

  @Container (1)
  public static DockerComposeContainer jenkinsServer =
      new DockerComposeContainer(new File("docker-compose.yml"))
          .withExposedService("jenkins", JENKINS_PORT)
          .waitingFor("jenkins", Wait.forLogMessage(".*Jenkins is fully up and running*\\n", 1)); (2)

  @Test
  void first_request_to_fresh_container_should_return_authentication_required()
      throws Exception {
    String jenkinsUrl = "http://"
        + jenkinsServer.getServiceHost("jenkins", JENKINS_PORT)
        + ":" +
        jenkinsServer.getServicePort("jenkins", JENKINS_PORT);

    MatcherAssert.assertThat("first request to fresh container should return \"Authentication required\"",
        callHttpEndpoint(jenkinsUrl),
        containsString("Authentication required")(3)
    );
  }

  private static String callHttpEndpoint(String url) throws IOException, InterruptedException { (4)
    HttpClient httpClient = HttpClient.newBuilder().build();
    HttpRequest mainRequest = HttpRequest.newBuilder()
        .uri(URI.create(url))
        .build();

    HttpResponse<String> response = httpClient.send(mainRequest, HttpResponse.BodyHandlers.ofString());
    return response.body();
  }

}

1	I use the TestContainers Docker Compose Module here.
2	As most applications Jenkins is not fully started, when the conainer is started. So I wait until the suitable Jenkins message shows up in the Docker container logs.
3	In my test I call the Jenkins URL end the response should show for this container, that Authentication is required.
4	Here you see the helper method for calling an HTTP URL and return the response.

If you run the test in your IDE, you will see a successful test, but following warning and miss maybe some logging for the call.

To solve this you have to add the following dependency to your pom.xml.

    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-api</artifactId>
      <version>2.0.16</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.slf4j</groupId>
      <artifactId>slf4j-simple</artifactId>
      <version>2.0.16</version>
      <scope>test</scope>
    </dependency>

If you run your test via Maven maybe you see now, that no test are executed.

-------------------------------------------------------
 T E S T S
-------------------------------------------------------

Results :

Tests run: 0, Failures: 0, Errors: 0, Skipped: 0

For running Unit 5 tests you have to change the maven-surefire-plugin in your pom.xml at least to 2.22.0.

      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-surefire-plugin</artifactId>
        <version>3.5.2</version>
      </plugin>

If you run your test now via Maven you should see an output similar like the following.

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running TestJenkins
...
[main] INFO docker[docker/compose:1.29.2] - Creating container for image: docker/compose:1.29.2
[main] INFO docker[docker/compose:1.29.2] - Container docker/compose:1.29.2 is starting: 56fee4602485802e21ef5292d14e6fadeccefb676286fb691ac0af04f7e209f3
[main] INFO docker[docker/compose:1.29.2] - Container docker/compose:1.29.2 started in PT7.4233676S
[main] INFO docker[docker/compose:1.29.2] - Docker Compose container is running for command: up -d
...
[main] INFO docker[docker/compose:1.29.2] - Docker Compose has finished running
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 38.101 s - in TestJenkins
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO]
...
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------

You can add a lot of other tests here, but for testing the TestContainers framework this should be enough here.

You find all sources on GitHub.

That’s it!