Como combinar "C", "C++" ou "C#"? [duplicado]

Tenho os seguintes casos de teste:

CPP_CSHARP_REGEX_TEST_CASES = [
    ("C++", True),
    ("C#", True),
    ("C+", False),
    ("C##", False),
    ("C", True),
]

Qual expressão regular eu poderia usar para passar pytest? Eu tentei r"^C[+{2},#{1}]$" a solução de Tim Biegeleisen, mas falha para C:

________________________________________________________________________________ test_cpp_csharpRegex[C-True] ________________________________________________________________________________

data = 'C', expected = True

    @pytest.mark.parametrize("data, expected", CPP_CSHARP_REGEX_TEST_CASES)
    def test_cpp_csharpRegex(data, expected):
        cpp_csharp_regex = r"\bC(?:\+\+|#)(?=\s|$)"
>       assert expected == bool(re.match(cpp_csharp_regex, data))
E       AssertionError: assert True == False
E        +  where False = bool(None)
E        +    where None = <function match at 0x7ab4e2cded40>('\\bC(?:\\+\\+|#)(?=\\s|$)', 'C')
E        +      where <function match at 0x7ab4e2cded40> = re.match

regex_test.py:131: AssertionError
================================================================================== short test summary info ===================================================================================
FAILED regex_test.py::test_cpp_csharpRegex[C-True] - AssertionError: assert True == False
================================================================================ 1 failed, 70 passed in 0.08s ================================================================================