java.lang.ClassNotFoundException: org.codehaus.groovy.transform.powerassert.ValueRecorder

Running a GroovyTestCase in a new project I got the following :

java.lang.NoClassDefFoundError: org/codehaus/groovy/transform/powerassert/ValueRecorder
   at [My Package Hierarchy].[My TestCase].[My Test Method]([My Test Case].groovy:29)
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
   at java.lang.reflect.Method.invoke(Method.java:597)
   at junit.framework.TestCase.runTest(TestCase.java:168)
   at junit.framework.TestCase.runBare(TestCase.java:134)
   at junit.framework.TestResult$1.protect(TestResult.java:110)
   at junit.framework.TestResult.runProtected(TestResult.java:128)
   at junit.framework.TestResult.run(TestResult.java:113)
   at junit.framework.TestCase.run(TestCase.java:124)
   at junit.framework.TestSuite.runTest(TestSuite.java:232)
   at junit.framework.TestSuite.run(TestSuite.java:227)
   at org.junit.internal.runners.JUnit38ClassRunner.run(JUnit38ClassRunner.java:79)
   at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46)
   at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
   at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
   at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
   at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
   at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.lang.ClassNotFoundException: org.codehaus.groovy.transform.powerassert.ValueRecorder
   at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
   at java.security.AccessController.doPrivileged(Native Method)
   at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
   at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
   at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
   at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
   ... 20 more

I found a bug that was closed because it couldn't be reproduced in the Groovy Eclipse JIRA.

I had run GroovyTestCases in other projects without this problem.

I right clicked the project and chose "Groovy -> Add Groovy libs to Classpath." That fixed it.

I had added my own Groovy library instead of the plugins. I often point Eclipse Libraries to the jar files in my .m2 directory. The "org.codehaus.groovy.transform.powerassert" package was not part of the Groovy distro. It is part of Groovy Eclipse plugin.