JUnit.org Resources for Test Driven Development

I have a maven project where I have, under the src/test/java tree, a class called server.common.ServerTestBase that serves as a base classfor other test classes.

For some reason this class is not found during test execution using "mvn test". Any idea what could cause this? The compiled class is under the target/test/classes.

TIA for your help

java.lang.NoClassDefFoundError: server.common.ServerTestBase
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Class.java:2395)
at java.lang.Class.getMethod0(Class.java:2642)
at java.lang.Class.getMethod(Class.java:1579)
at org.junit.internal.requests.ClassRequest.hasSuiteMethod(ClassRequest.java:61)
at org.junit.internal.requests.ClassRequest.getRunnerClass(ClassRequest.java:50)
at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:28)
at org.apache.maven.surefire.junit4.JUnit4TestSet.(JUnit4TestSet.java:45)
at org.apache.maven.surefire.junit4.JUnit4DirectoryTestSuite.createTestSet(JUnit4DirectoryTestSuite.java:56)
at org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.locateTestSets(AbstractDirectoryTestSuite.java:96)
at org.apache.maven.surefire.Surefire.createSuiteFromDefinition(Surefire.java:150)
at org.apache.maven.surefire.Surefire.run(Surefire.java:111)
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:585)
at org.apache.maven.surefire.booter.SurefireBooter.runSuitesInProcess(SurefireBooter.java:290)
at org.apache.maven.surefire.booter.SurefireBooter.main(SurefireBooter.java:818)