Even there is not option how to create test for new Seam action and form in "New Seam Web project wizard", there is following option, how you can create this test, which is then not valid at all:

1. New -> Seam Action
2. Click on the settings link in the dialog
3. Mark checkbox "Create test"

This should be either disabled or you can use seam-gen ant solution and fetch test libraries from Seam runtime.