Maven plugin development - how to ensure building for Maven 3.0.x instead of 3.1.x?

Question

I'm trying to develop a custom Maven plugin. I'm currently running into this problem when I execute my unit tests: java.lang.NoClassDefFoundError: org.eclipse.aether.RepositorySystemSession Stack trace is below:

initializationError(com.mycompany.MyPluginTest)  Time elapsed: 0 sec  (TestSuite.java:132)
    at org.junit.internal.runners.JUnit38ClassRunner.(JUnit38ClassRunner.java:72)
    at org.junit.internal.builders.JUnit3Builder.runnerForClass(JUnit3Builder.java:11)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)
    at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:26)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)
    at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:26)
    at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:262)
    at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:153)
    at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:124)
    at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:200)
    at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153)
    at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:103)
Caused by: java.lang.ClassNotFoundException: org.eclipse.aether.RepositorySystemSession
    at java.net.URLClassLoader.findClass(URLClassLoader.java:423)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:660)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:346)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:626)
    at java.lang.J9VMInternals.verifyImpl(Native Method)
    at java.lang.J9VMInternals.verify(J9VMInternals.java:72)
    at java.lang.J9VMInternals.verify(J9VMInternals.java:70)
    at java.lang.J9VMInternals.initialize(J9VMInternals.java:134)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:44)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:516)
    at junit.framework.TestSuite.createTest(TestSuite.java:63)
    at junit.framework.TestSuite.addTestMethod(TestSuite.java:310)
    at junit.framework.TestSuite.addTestsFromTestCase(TestSuite.java:153)
    at junit.framework.TestSuite.(TestSuite.java:132)
    at org.junit.internal.runners.JUnit38ClassRunner.(JUnit38ClassRunner.java:72)
    at org.junit.internal.builders.JUnit3Builder.runnerForClass(JUnit3Builder.java:11)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)
    at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:26)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)
    at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:26)
    at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:262)
    at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:153)
    at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:124)
    at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:200)
    at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:153)
    at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:103)

From my research, this can happen when building for Maven 3.1.x because Maven switched from the sonatype aether implementation to the eclipse implementation.

I am trying to build my plugin for Eclipse 3.0.4, since that's what's installed on all our workstations. I'm assuming that I'm seeing this error because one of my dependencies is a Maven 3.1.x dependency, although I'm not sure which one. Does anyone know which dependency I should correct?

Also, does anyone know if it's possible to build a plugin that will work for Maven 3.0.x and 3.1.x? I'd rather not have to go through all this again some day in the future when we move to a newer version of Maven.

The dependencies in my POM look like this:

<dependencies>
    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-plugin-api</artifactId>
        <version>3.0.4</version>
    </dependency>
    <dependency>
        <groupId>org.apache.maven.plugin-tools</groupId>
        <artifactId>maven-plugin-annotations</artifactId>
        <version>3.0</version>
    </dependency>
    <dependency>
        <groupId>org.apache.maven.plugin-tools</groupId>
        <artifactId>maven-plugin-tools-api</artifactId>
        <version>3.0</version>
    </dependency>
    <dependency>
        <groupId>org.apache.maven.plugin-testing</groupId>
        <artifactId>maven-plugin-testing-harness</artifactId>
        <version>3.0.0</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.11</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-resources-plugin</artifactId>
        <version>2.6</version>
    </dependency>
    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-compat</artifactId>
        <version>3.0.4</version>
    </dependency>
    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-model</artifactId>
        <version>3.0.4</version>
    </dependency>
</dependencies>

Roath

Can you show your plugin code? May be github project? – Alathia

Anyone else find it ironic that the people maintaining the test fixtures for the dependency management build tool did dependency management wrong? – Chelyuskin

Answer 1

Ok, so I think I figured out the issue with aether: it appears to depend on which version of maven-plugin-testing-harness is being used. Version <= 2.1 seems to use sonatype aether. Using this set of dependencies resolves the aether problem:

    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-artifact</artifactId>
        <version>3.0.5</version>
    </dependency>

    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-compat</artifactId>
        <version>3.0.5</version>
    </dependency>

    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-plugin-api</artifactId>
        <version>3.0.5</version>
    </dependency>

    <dependency>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-resources-plugin</artifactId>
        <version>2.6</version>
    </dependency> 

    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-core</artifactId>
        <version>3.0.5</version>
    </dependency>  

    <dependency>
        <groupId>org.apache.maven.plugin-tools</groupId>
        <artifactId>maven-plugin-annotations</artifactId>
        <version>3.1</version>
    </dependency>
    <dependency>
        <!-- version 2.1 uses sonatype aether. anything after 2.1 uses eclipse aether. -->
        <groupId>org.apache.maven.plugin-testing</groupId>
        <artifactId>maven-plugin-testing-harness</artifactId>
        <scope>test</scope>
        <version>2.1</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.11</version>
        <scope>test</scope>
    </dependency>

Roath

Basically if you consider the provided dependencies mvnrepository.com/artifact/org.apache.maven.plugin-testing/… you have the list of the dependency you have to include. I have spot this reading your answer and having a look at the mvncentral. IMHO should be just a dependency to add, clear and simple to make the test easier. – Boardinghouse

Answer 2

Slightly more confusingly than moving to the eclipse aether dependency, a lot of the dependencies of the maven-plugin-testing-harness had the scope changed from compile to provided which means they're not resolved by your downstream dependency.

It seems like this was actually experienced in Fedora as well, and they raised this issue with apache which hasn't had an attention in over a year...

On they apache bug, they state that you'll have to add dependencies on maven-core, maven-model, maven-aether-provider but on having a look at the dependencies of maven-plugin-testing-harness there are other provided scope dependencies.

The dependencies I had to add to persuade everything to work with plugin testing harness 3.3 were:

<dependency>
    <groupId>org.apache.maven.plugin-testing</groupId>
    <artifactId>maven-plugin-testing-harness</artifactId>
    <version>3.3.0</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.apache.maven</groupId>
    <artifactId>maven-compat</artifactId>
    <version>3.3.3</version>
</dependency>
<dependency>
    <groupId>org.apache.maven</groupId>
    <artifactId>maven-core</artifactId>
    <version>3.3.3</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>maven</groupId>
    <artifactId>maven-model</artifactId>
    <version>3.0.2.javadoc</version>
    <type>javadoc.jar</type>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.apache.maven</groupId>
    <artifactId>maven-aether-provider</artifactId>
    <version>3.3.3</version>
    <scope>test</scope>
</dependency>
<dependency>
  <groupId>org.apache.maven</groupId>
  <artifactId>maven-plugin-api</artifactId>
  <version>3.3.3</version>
</dependency>
<dependency>
  <groupId>org.apache.maven.plugin-tools</groupId>
  <artifactId>maven-plugin-annotations</artifactId>
  <version>3.2</version>
  <scope>provided</scope>
</dependency>
<dependency>
  <groupId>org.codehaus.plexus</groupId>
  <artifactId>plexus-utils</artifactId>
  <version>3.0.15</version>
</dependency>

Dubbing

Glad you linked the associated bug. I wish all 2500+ viewers of this question would just go vote on it now ;) – Chelyuskin

Answer 3

So, interesting and weird enough, answers provided above didn't work for me. Did some digging around and found nothing. Finally came full circle when visited the plugin URL: http://maven.apache.org/plugin-testing/maven-plugin-testing-harness/dependency-convergence.html

The "Dependency Convergence" section provides all dependencies versions required to ensure the plugin 'lights up'. In a matter of seconds all was working. Here's a snippet of what I eventually had in my pom:

    <dependency>
        <groupId>org.apache.maven.plugin-testing</groupId>
        <artifactId>maven-plugin-testing-harness</artifactId>
        <version>3.3.0</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-compat</artifactId>
        <version>3.2.5</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-core</artifactId>
        <version>3.2.5</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-model</artifactId>
        <version>3.2.5</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-aether-provider</artifactId>
        <version>3.2.5</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.maven</groupId>
        <artifactId>maven-plugin-api</artifactId>
        <version>3.2.5</version>
    </dependency>
    <dependency>
        <groupId>org.apache.maven.plugin-tools</groupId>
        <artifactId>maven-plugin-annotations</artifactId>
        <version>3.3</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.11</version>
        <type>jar</type>
        <scope>test</scope>
    </dependency>

Hope this helps someone out there :)

Burrow