Sanity check special case params are being generated

Author: honno

Diff for: array_api_tests/test_special_cases.py

@@ -1197,6 +1197,10 @@ def parse_binary_case_block(case_block: str) -> List[BinaryCase]:
 # its False - Hypothesis will complain if we reject too many examples, thus
 # indicating we've done something wrong.
 
+assert len(unary_params) != 0  # sanity check
+assert len(binary_params) != 0  # sanity check
+assert len(iop_params) != 0  # sanity check
+
 
 @pytest.mark.parametrize("func_name, func, case", unary_params)
 @given(