Automate simple tests cases

[johnnv1]

          not for this pull request, but to ease development we could consider to somehow automate the old abstract methods (maybe with some decorators)

Originally posted by @edgarriba in #2745 (comment)

just for the record, the old methods that we used in the base test class as abstracts were:

    def test_smoke(self, device, dtype):
        # test the function with different parameters arguments, to check if the function at least runs with all the
        # arguments allowed.
        pass

    def test_exception(self, device, dtype):
        # tests the exceptions which can occur on your function

        # example of how to properly test your exceptions
        # with pytest.raises(<raised Error>) as errinfo:
        #     your_function(<set of parameters that raise the error>)
        # assert '<msg of error>' in str(errinfo)

        pass

    def test_cardinality(self, device, dtype):
        # test if with different parameters the shape of the output is the expected
        pass

    def test_feature_foo(self, device, dtype):
        # test basic functionality
        pass

    def test_feature_bar(self, device, dtype):
        # test another functionality
        pass

    def test_gradcheck(self, device):
        # test the functionality gradients
        # Uses `self.gradcheck(...)`
        pass