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Cannot use Mock interface method with MultipartFormDataStreamProvider parameter

I have this weird problem while trying to spoof an interface using MockedClass.Setup (x => x.Method ()).

This is the interface I'm mocking.

public interface IClassFactory
{
    object GetValueFromFormData(string key, MultipartFormDataStreamProvider provider);
}

This is my test.

    [TestMethod]
    [ExpectedException(typeof(NullReferenceException))]
    public async Task ClassApiController_ImportClassList_ThrowsNullReferenceExceptionWhenNoClassId()
    {
        // Arrange
        _classFactory = new Mock<IClassFactory>();

        // THIS IS THE LINE THAT GIVES AN EXCEPTION
        _classFactory.Setup(x => x.GetValueFromFormData("classIdNull", null)).Returns(string.Empty);
        ClassApiController controller = new ClassApiController(_classRepository.Object, _surveyRepository.Object, _classFactory.Object);

        // Act
        string result = await controller.ImportClassList();
    }

If you look at my comment "THIS IS THE LINE WHAT GIVES THE EXCEPTION" you can see that I am sending null, but it doesn't matter if I am sending MultipartFormDataStreamProvider

as an instansiated class, I still get the same exception.

Exception message: System.ArgumentException: Expression of type 'System.Net.Http.MultipartFormDataStreamProvider' cannot be used for parameter of type 'System.Net.Http.MultipartFormDataStreamProvider' of method 'System.Object GetValueFromFormData(System.String, System.Net.Http.MultipartFormDataStreamProvider)'

If you know why I can't mock a method just because it has this object as a parameter, please help me, I don't know.

Thank!

EDIT: See the solution in my answer

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2 answers


With the help of @ Vignesh.N, I finally solved this. The simple answer in this case was that my solution is split across multiple projects. Web, Test, Data, etc. In the web project, I referenced the api.dll: s website through Nuget, and in the test project, I directly referenced them through Add references -> Assemblies -> Framework

. Thus, the .dll: s files had identical versions, but not the files. After Nuget took care of all web api.dll projects, it worked instantly.



So, in general, a silly mistake and difficult to spot.

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try it



        _classFactory = Mock.Of<IClassFactory>();

        Mock.Get(_classFactory).Setup(x => x.GetValueFromFormData("classIdNull", It.IsAny<MultipartStreamProvider>()))
                     .Returns(string.Empty);
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