JUnit4 plug-in and build path for junit.jar in Eclipse

I've got Eclipse (Helios) installed along with the JUnit3, JUnit4 and Java Development Tools plug-ins for some Android development.

I've c开发者_运维知识库reated some unit tests but the only way they run (without throwing a java.lang.ClassNotFoundException for org.junit.Test) is if I add an External JAR to the test project build path for junit.jar from the normal JUnit install I have.

Why isn't Eclipse able to reference the junit.jar from the JUnit4 plugin which I can see when I expand the library in Package Explorer? In fact I can remove the JUnit4 Library from the test project leaving just the External JAR and the tests run fine.

I tried adding the path to the plug-in folder to my CLASSPATH system environment variable as I had to setting up JUnit but this made no difference. The plugin path is created as a JUNIT_HOME Classpath Variable in Eclipse but this is labeled as deprecated.

Do I even need the JUnit3 and JUnit4 plugins as these must have come with the distro I used?

In any new project, the sure way I add the required Junit deps (with the exception of declaring them in maven) is through creating the test using the in-built Junit test shortcut.

Go to New > Junit Test Case. If the right deps are not on the project classpath, eclipse will pull them in automatically.