Maven assembly plugin complains about no files whatever I do

Question

I have a similar situation to Add jar-with-dependencies artifact from other Maven module, however the suggested solution did not work for me. I've tried using both moduleSets and dependencySets. So here we go:

Introduction:

I have a multi-module maven project:

parent
|
+-myProject
|
+-myProjectTests

I want myProjectTests to have the jar-with-dependencies produced by myProject in its output directory, to run integration tests etc on (I'm using a framework that requires an actual jar to run)

parent pom.xml:

<project>
  <groupId>myGroup</groupId>
  <artifactId>parent</artifactId>
  <packaging>pom</packaging>
  
  <modules>
    <module>myProject</module>
    <module>myProjectTests</module>
  </modules>
</project>

myProject pom.xml:

<project>
  <groupId>myGroup</groupId>        
  <artifactId>myProject</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <build>
    <plugins>    
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
          <configuration>
            <descriptorRefs>
              <descriptorRef>jar-with-dependencies</descriptorRef>
            </descriptorRefs>
          </configuration>
        </plugin>
      </plugins>
    </build>
  </plugins>
</project>

myProjectTests pom.xml:

<project>

  <groupId>myGroup</groupId>
  <artifactId>myProjectTests</artifactId>
  <version>0.0.1-SNAPSHOT</version>    
  <packaging>pom</packaging>

  <dependencies>
    <dependency>
      <groupId>myGroup</groupId>
      <artifactId>myProject</artifactId>
      <version>0.0.1-SNAPSHOT</version>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <artifactId>maven-assembly-plugin</artifactId>
        <version>2.4</version>
        <executions>
          <execution>
            <id>prepareTests</id>
            <phase>package</phase>
            <goals>
              <goal>single</goal>
            </goals>
            <configuration>
              <descriptors>
                <descriptor>prepare.xml</descriptor>
              </descriptors>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

prepare.xml:

<assembly>      
  <id>prepareTests</id>
  <formats>
    <format>dir</format>
  </formats>

  <includeBaseDirectory>false</includeBaseDirectory>
  ?????
</assembly>

moduleSets:

If I try specifying moduleSets for the ????? in my prepare.xml like so:

<moduleSets>
  <moduleSet>
    <useAllReactorProjects>true</useAllReactorProjects>
    <includes>
      <include>myGroup:myProject</include>
    </includes>
    <binaries>
      <attachmentClassifier>jar-with-dependencies</attachmentClassifier>
      <unpack>false</unpack>
    </binaries>
  </moduleSet>
</moduleSets>

I get this output:

[WARNING] The following patterns were never triggered in this artifact inclusion filter:
o  'myGroup.myProject'

[WARNING] The following patterns were never triggered in this artifact inclusion filter:
o  'myGroup.myProject'

[WARNING] NOTE: Currently, inclusion of module dependencies may produce unpredictable results if a version conflict occurs.

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-assembly-plugin:2.4:single (prepareTests) on project myProjectTests: Failed to create assembly: Error creating assembly archive prepareTests: You must set at least one file. -> [Help 1]

I have scoured the maven documentation and the internets for solutions, and have tried many different combinations of the various flags, all with the same error.

dependencySets:

If I specify dependencySets in the ????? like so:

<dependencySets>
  <dependencySet>
    <includes>
      <include>myGroup:myProject:jar-with-dependencies:0.0.1-SNAPSHOT</include>
    </includes>
    <unpack>false</unpack>
  </dependencySet>
</dependencySets>

I get this:

[WARNING] Cannot include project artifact: myGroup:myProjectTests:pom:0.0.1-SNAPSHOT; it doesn't have an associated file or directory.
[WARNING] The following patterns were never triggered in this artifact inclusion filter:
o  'myGroup:myProject:jar-with-dependencies:0.0.1-SNAPSHOT'

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-assembly-plugin:2.4:single (prepareTests) on project myProjectTests: Failed to create assembly: Error creating assembly archive prepareTests: You must set at least one file. -> [Help 1]

Again, I have tried lots of different combinations of flags, and removed the jar-with-dependencies classifier, all to no effect.

There is nothing in the debug logs in both cases that is helpful, and I have explored some avenues suggested by the debug logs.

What I want is simple - to have the jar-with-dependencies file produced by myProject to be put into the output directory of myProjectTests during the package phase, ideally without using direct file paths. How do I get maven to do that?

Answer 1

Turns out this is a known maven bug - the assembly plugin doesn't work correctly when the submodules don't have the aggregator project as its parent - MASSEMBLY-600. Looks like I'll have to use direct file dependencies instead.