How to implement XUnit descriptive Assert message?

Question

Context

in XUnit github I found this: Add Assert.Equal(expected, actual, message) overload #350 (so a developer ask for a non existing overload see

Answer 1

I was having the same issue. I've a test that pulls data from two web api's and then compares and asserts various things about the content. I started using standard XUnit assertions like:

Assert.Equal(HttpStatusCode.OK, response1.StatusCode);
Assert.Equal(HttpStatusCode.OK, response2.StatusCode);

But whilst this gives a useful message that a 404 has been returned, it not clear from the logs on our build/CI server which service caused the error message.

I ended up adding my own assertion to give context:

public class MyEqualException : Xunit.Sdk.EqualException
{
    public MyEqualException(object expected, object actual, string userMessage)
        : base(expected, actual)
    {
        UserMessage = userMessage;
    }

    public override string Message => UserMessage + "\n" + base.Message;
}

public static class AssertX
{
    /// 

    /// Verifies that two objects are equal, using a default comparer.
    /// 
    /// The type of the objects to be compared
    /// The expected value
    /// The value to be compared against
    /// Message to show in the error
    /// Thrown when the objects are not equal
    public static void Equal(T expected, T actual, string userMessage)
    {
        bool areEqual;

        if (expected == null || actual == null)
        {
            // If either null, equal only if both null
            areEqual = (expected == null && actual == null);
        }
        else
        {
            // expected is not null - so safe to call .Equals()
            areEqual = expected.Equals(actual);
        }

        if (!areEqual)
        {
            throw new MyEqualException(expected, actual, userMessage);
        }
    }
}

Then I can do the same assertions as:

AssertX.Equal(HttpStatusCode.OK, response1.StatusCode, $"Fetching {Uri1}");
AssertX.Equal(HttpStatusCode.OK, response2.StatusCode, $"Fetching {Uri2}");

and the error log gives the actual,expected and prepends my message about which webapi was the culprit.

I realise I'm late to answer, but figured this might help others searching for a practical solution that don't have time to install/learn yet another test framework just to get useful information out of test failures.