Improve "Member x does not exist" failure message

[jessfdm-codes]

Currently an ArgumentException is thrown when a .Protected().Verify(methodName, times, arguments) call is made when arguments doesn't match the arguments in methodName's signature which just states System.ArgumentException : Member Class.Method does not exist..

For example, if mocking a HttpMessageHandler you would use the following code to check if SendAsync was called with any (correct type) arguments:

mockHttpMessageHandler.Protected().Verify(
           "SendAsync",
           Times.Exactly(1),
           ItExpr.IsAny<HttpRequestMessage>(),
           ItExpr.IsAny<CancellationToken>()
);

If I was to accidentally use the wrong generic type for one of the arguments (for example string instead of CancellationToken) my code would instead look like this:

mockHttpMessageHandler.Protected().Verify(
           "SendAsync",
           Times.Exactly(1),
           ItExpr.IsAny<HttpRequestMessage>(),
           ItExpr.IsAny<string>()
);

and, then the test is run would give the following error:

System.ArgumentException : Member HttpMessageHandler.SendAsync does not exist.

This gives the impression that there is no such method as SendAsync at all in the class, whereas it's only the case that there isn't a SendAsync signature which takes (HttpRequestMessage, string). Might it be worth updating this error message to include the erroneous signature i.e. something like:

System.ArgumentException: Member HttpMessageHandler.SendAsync(HttpRequestMessage, string) does not exist.

to make it easier to debug why tests are failing?

[stakx]

@thomasfdm, not sure how often people run into this problem, but having good diagnostic messages can't hurt. Would you like to submit a PR?

[jessfdm-codes]

Happy to give it a go, but no definite ETA on it 😄

[jessfdm-codes]

I'll try and get it done today

[stakx]

@thomasfdm - One thing to keep in mind (IIRC): It might be wrong to assume that the method parameter list has to match exactly with the provided arguments. (For example, on some .Protected().... method overloads, you might request exactParameterMatch: false.) So it might be more correct to generate an error message saying, "No protected method X was found whose parameters are compatible with those provided: (T1, T2, T3, ...)", instead of, "No protected method X(T1, T2, T3, ...) found." The latter might be just as misleading (or worse) as what we have now.

[jessfdm-codes]

Good catch, I've changed my error message accordingly:
No Protected Method Class.Method found whose parameters are compatible with provided types (T1, T2, ... Tx)

I've now got the method to generate it, just need to replace the calls from ThrowIfMissingMember to this new method. I'll leave the previous message in place for properties as it is at the moment.