IsAssignableFrom breaks __ComObject support

[bob-fisher]

trying to setup setter for a property of ISymbol type, which is COM interface:
ISymbol setSymbol = null;
elMock.SetupGet(e => e.Symbol).Returns(setSymbol);
elMock.SetupSet(e => e.Symbol = It.IsAny()).Callback(s => setSymbol = s);

set it during a test:
el.Symbol = (ISymbol)Com.CreateInstance();

this never works, setSymbol stays null, Symbol property also always returns null

[stakx]

Let's start with the getter:

Symbol property also always returns null

That's because you configured it to return null. At the moment when .Returns(setSymbol) executes, setSymbol is null, therefore that call is equivalent to .Returns(null). Did you perhaps mean:

elMock.SetupGet(e => e.Symbol).Returns(() => setSymbol);  // deferred evaluation using lambda

[stakx]

Regarding the setter, there seems to be a problem, indeed. It.IsAny<T> won't recognize an instance of T is that is a COM object.

You mentioned IsAssignableFrom in this issue's title. I'm assuming you're referring to the one inside It.IsAny<T>():

public static TValue IsAny<TValue>()
{
    return Match<TValue>.Create(
        value => value == null || typeof(TValue).IsAssignableFrom(value.GetType()),
        () => It.IsAny<TValue>());
}

typeof(TValue).IsAssignableFrom(value.GetType()) might indeed not work for a COM object. This could apparently be solved by changing the test to value is TValue.