[SUREFIRE-1420] Support running unit tests in named Java 9 modules

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Duplicate
• Assignee: Robert Scholte
• Reporter: Gunnar Morling
• Created: 22/Sep/17 09:56
• Updated: 23/Sep/17 10:14
• Resolved: 23/Sep/17 10:14

Description

As far as I can tell, Surefire will run tests using the traditional classpath also on Java 9. When the project that is built is a named Java 9 module (i.e. it contains a module descriptor), it'd be desirable to have a way to run the tests using the module path instead.

For that, the following things would be required:

• Adding the currently built project and its dependencies to the module path instead of the class path when forking the java process running the tests
• Adding a read edge from the currently built module to the used testing library, e.g. JUnit, if it's not present as a dependence in the module descriptor already (which it usually won't)
• Patching the classes from target/test-classes into the currently built module (as represented by the classes under target/classes)
• Opening up packages containing tests to the testing library so they can be accessed reflectively

I could perform these steps manually by applying the following configuration for the Surefire plug-in:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-surefire-plugin</artifactId>
    <version>2.20.1</version>
    <configuration>
        <!-- Don't add any dependencies to the class path -->
        <classpathDependencyScopeExclude>test</classpathDependencyScopeExclude>

        <argLine>--module-path=target/classes:/path/to/junit/junit/4.12/junit-4.12.jar:
                               /path/to/org/hamcrest/hamcrest-core/1.3/hamcrest-core-1.3.jar
                 --add-modules com.example,junit,hamcrest.core
                 --add-reads com.example=junit
                 --add-opens com.example/com.example.internal=junit
                 --patch-module com.example=target/test-classes</argLine>
        
        <!-- Prevents target/classes to be added to the classpath -->                
        <classesDirectory>path/to/none</classesDirectory>

        <!-- Doing the same for test classes failed as it caused no tests to be found; it still works, 
              I assume the --patch-module above takes precedence over their occurrence on the classpath -->
        <!-- <testClassesDirectory>path/to/none</testClassesDirectory> -->
    </configuration>
</plugin>

Ideally, an equivalent java invocation would be done by Surefire automatically when building a named module.

Issue Links

• duplicates: SUREFIRE-1262 Add modulepath support