Question

This seems like an easy enough issue but I can’t seem to find the keywords to effect my searches.

I’m trying to unit test by mocking out all objects within this method call. I am able to do so to all of my own creations except for this one:

public void MyFunc(MyVarClass myVar)
{
    Image picture;
    ...

    picture = Image.FromStream(new MemoryStream(myVar.ImageStream));

    ...
}

FromStream is a static call from the Image class (part of c#). So how can I refactor my code to mock this out because I really don’t want to provide a image stream to the unit test.

Answer 1

You could wrap the static function into Func type property which can be set by the unit test with a mock or stub.

public class MyClass
{
    ..

    public Func<Image, MemoryStream> ImageFromStream = 
                                     (stream) => Image.FromStream(stream);


    public void MyFunc(MyVarClass myVar)
    {
        ...

        picture = ImageFromStream(new MemoryStream(myVar.ImageStream));

        ...
    }


    ..
}