[SOLVED] Eclipse No tests found using JUnit 5 caused by NoClassDefFoundError for LauncherFactory

Eclipse No tests found using JUnit 5 caused by NoClassDefFoundError for LauncherFactory

The problem

Whenever I run my projects JUnit test (using JUnit 5 with Java 9 and Eclipse Oxygen 1.a) I encounter the problem that eclipse can't find any tests.

The description

Under the run configuration, eclipse can't even find the method which is annotated with @Test, but instead only shows me "(all methods)". The following picture hopefully gives a better glimps of my setup:

Console output:

java.lang.NoClassDefFoundError: org/junit/platform/launcher/core/LauncherFactory
    at org.eclipse.jdt.internal.junit5.runner.JUnit5TestLoader.<init>(JUnit5TestLoader.java:31)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
    at java.base/java.lang.reflect.Constructor.newInstance(Unknown Source)
    at java.base/java.lang.Class.newInstance(Unknown Source)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.createRawTestLoader(RemoteTestRunner.java:368)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.createLoader(RemoteTestRunner.java:363)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.defaultInit(RemoteTestRunner.java:307)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.init(RemoteTestRunner.java:222)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:206)
Caused by: java.lang.ClassNotFoundException: org.junit.platform.launcher.core.LauncherFactory
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(Unknown Source)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(Unknown Source)
    at java.base/java.lang.ClassLoader.loadClass(Unknown Source)
    ... 11 more

What I tried so far

I've already tried

to remove the test folder from build path and add it again.
to start the test with hovering over the method annotated with @Test and then click "Run as JUnit Test".
remove JUnit from Buildpath and add it again
restart eclipse
I've also moved the project whole project from one machine to another machine and tried it with the provided eclipse installation there
to rename the test method.
to retype the @Test annotation

Some of these steps can be found here, but in the end the problem remained.

Solution

You ran into Eclipse bug 525948 which has already been fixed and which will be published in the upcoming release Oxygen.3 (4.7.3), March 21, 2018.

As workaround, put your test code in a separate project and add the project under test to the modulepath, but do not add a module-info.java to your test project. With your project, class and module naming, it should look something like this: