Test on build with Maven

Let's add some testing to the tiny mavenized Java app seen in the previous couple of posts.

Actually, the app is so tiny that there is that there's nothing to test. This is easily solved, adding a method to the Main class

public static String getLoggerClassName() {
    return LOG.getClass().getName();
}

I plan to use JUnit 5 (aka Jupiter) as testing framework, asserting via Hamcrest, so I add both these dependencies to the POM.

<dependency>
    <groupId>org.junit.jupiter</groupId>
    <artifactId>junit-jupiter-engine</artifactId>
    <version>5.6.2</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.hamcrest</groupId>
    <artifactId>hamcrest</artifactId>
    <version>2.2</version>
    <scope>test</scope>
</dependency>

As I said, I plan to use JUnit and Hamcrest for testing only. I don't want to bother the user with them. That's the reason why I signaled to Maven that their scope is test.

Now I write a test for the newly added method

@Test
void getLoggerClassName() {
    String actual = Main.getLoggerClassName();
    assertThat(actual, is("ch.qos.logback.classic.Logger"));
}

I can run it from Eclipse in the usual way, anything works fine.

I build the app with Maven, clean package, and I get both my jars, slim and fat, as before. In both cases without the test dependencies, and that's good. Still, something is missing. Tests are not executed in this phase. Bad. I'd like to check anything works fine when I build my jar.

The issue is in the Maven Surefire Plugin. By default, an ancient version is executed that do not work nicely with JUnit 5. So, I force Maven to use a newer one. It's name is a bit scary, having an M in its version number. M as Milestone. However, it looks like we have to live with it. So I use it.

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <version>3.0.0-M4</version>
</plugin>

Actually, there's no need to specify the group id in this case, since maven plugins is the default. Your choice.

That's it. Now the Maven package build trigger also the execution of the tests. Nice.

I have pushed the full code on GitHub. So, please, check there for details.