This makes for some bad interactions with command-line builds, which compile tests to target/test-classes. Since (I presume) target/test-classes takes higher precedence on the classpath than target/classes, if a test is edited and run in the IDE after a command line build, the old .class file from target/test-classes will be used, not the new, IDE-compiled one in target/classes.
A fix would be to make IDE-compiled .class files from sources in src/test/scala go to target/test-classes.
Discussion with more info on scala-ide-user:
This is a rather annoying bug.
I can't reproduce.
What are your version of :
And can you share your .classpath