Question

What is the best practice for unit testing these kind of methods?

public VerificationResultCode Translate(int value)
    {
        VerificationResultCode result;

        if (Enum.IsDefined(typeof(VerificationResultCode), (int)value))
            result = (VerificationResultCode)((int)value);
        else
            throw new UnknownResultReturnFromGatewayException();

        return result;
    }

VerificationResultCode is Enum Type like:

public enum VerificationResultCode 
{
        BankingNetworkError = 100,
        NotEqual =101,
        InputFormatError = 102,
        MerchantAuthenticationFailed = 103,

...
}

Should we write a single test method for each of Enum Members or just write one test method with lots of Assertions?

Answer 1

The code is almost too trivial to unit test. You should unit test the behavior that depends on the VerificationResultCode which will also test the Translate function. A bigger question is why do you need a public translation function instead of encapsulating it in objects?