JUnit Plug-in tests are used to write unit tests for your plug-ins. The tests themselves look exactly like any other JUnit test.
The difference with JUnit Plug-in s is in how they are executed. Instead of using the standard JUnit class TestRunner, JUnit Plug-in tests are executed by a special test runner that launches another Eclipse instance in a separate VM-just like a runtime workbench-and executes the test methods within that workbench. This means your tests can call Eclipse Platform API, along with methods from your own plug-in, to exercise the functionality you want to test.
JUnit Plug-in tests are launched by selecting your test class and pressing Run > Run As > JUnit Plug-in Test. On the Arguments tab of the launch configuration dialog, you can choose what Eclipse application will be used to run your tests. By default, the Eclipse IDE workbench is used. If you are not testing user-interface components, you can choose [No Application] - Headless Mode. If you have written your own Eclipse application-such as a rich client application-you will need to write your own test runner application as well.