What should I do about “Possible compare of value type with 'null'”?

Question

While writing this method for a custom NUnit Constraint.

    private void AddMatchFailure(string failureName, TExpected expected, TActu         


        

Answer 1

private void AddMatchFailure(string failureName, TExpected expected, TActual actual)
{
    _matchFailures.Add(
        String.Format(MatchFailureFormat, failureName,
        (expected == default(TExpected)) ? "null" : expected.ToString(),
        (actual == default(TActual)) ? "null" : actual.ToString()));
}

Should do it.

default(T) gives the default value for that type, for reference types that's null - for others it depends. (Enums it's the equivalent of (enumType)0 for example).