If you don't want to create anything in the database you can do this:
employee = mock_model(Employee)
task = mock_model(Task, name: "Do that", employee: employee)
Keep in mind that you can't query them like that. It's roughly the same as building the object. If you ever want to do anything where you need to query actual data such as an integration test then you'll need use create
to make stuff in the database. Or as one commenter pointed out, you can use FactoryGirl's methods to stub stuff out.