Select File/New/Other then Test/TPTP JUnit Plugin Test:

At this point you may receive the New Test Case dialog:

If so, click on Yes. Then click on Next.

Provide the source folder (pluginProj/src in the example), the Package (tests), and the name of the JUnit Plug-in Test (EclipseUiTest).

Select either 'In the test editor' or 'In the code editor' for the test behavior option.

Click on Next and provide the test's name and location:

 

Click on Next and provide a description (if required):

Finally, click on Finish.

We now have a TPTP JUnit Plug-in Project Test named EclipseUiTest.