private static SignatureValidator GetValidator(IMethodSymbol method)
        {
            // Find the first matching attribute type in the table
            var attributeKnownType = method.FindFirstTestMethodType();

            if (attributeKnownType == null)
            {
                return(NullValidator);
            }

            return(attributeToConstraintsMap.GetValueOrDefault(attributeKnownType));
        }