Question

I tried to make a generic helper method using Moq with nunit as described below

public void PrepareWebRequest<T>() where T : new()
    {            
        httpCommunicator = new Mock<IHttpCommunicator>();
        httpCommunicator.Setup(x => x.Post(It.IsAny<Object>(),
                                                      It.IsAny<string>())).Throws<T>();

        service = new ApiClient(httpCommunicator.Object);
    }

But this causes the following error:

The type ‘T’ cannot be used as type parameter ‘TException’ in the generic type or method ‘Moq.Language.IThrows.Throws()’. There is no boxing conversion or type parameter conversion from ‘T’ to ‘System.Exception’.

I know this can be refactored by not using the generic method on Moq, but would really like to know what I’m doing wrong.

Best regards
Rasmus

Answer 1

Problem was a missing Exception in the Where clause. Should be

public void PrepareWebRequest<T>() where T : Exception, new()
{            
    httpCommunicator = new Mock<IHttpCommunicator>();
    httpCommunicator.Setup(x => x.Post(It.IsAny<Object>(),
                                                  It.IsAny<string>())).Throws<T>();

    service = new ApiClient(httpCommunicator.Object);
}