How to fake a type that have `dynamic` (ExpandoObject) properties? about fakeiteasy HOT 3 CLOSED

Hi, @FixRM. Sorry you're having a hard time.

I have never used dynamics so am not coming in with much experience, but it does seem that the dynamic type of the value supplied to Returns is causing the problem (not the type of CallerState; I was surprised). I think dynamic values infect things they touch. I was trying to write a test to reproduce your problem and FluentAssertions was also messed up: fake.CallerState.MyProp.Should().Be(42) fails.

A little digging tells me that a well-known effect of using dynamic is that you can no longer use extension methods on objects.

Anyhow, even before I dug, I found that

var fake = A.Fake<IHubCallerConnectionContext>();
dynamic state = new ExpandoObject();
state.MyProp = 42;
A.CallTo(() => fake.CallerState).Returns((object)state);

// I can even set and test the values later:
bool same1 = 42 == fake.CallerState.MyProp;
same1.Should().Be(true);

fake.CallerState.AnotherProp = 3;
bool same2 = 3 == fake.CallerState.AnotherProp;
same2.Should().Be(true);

works. It's not the most elegant, but I think is preferable to using ReturnsLazily (you may not feel the same 😉).

I can try to look more later, but given the weirdness of dynamic, I'm not sure we're going to get to a better "solution". If nothing else, there's probably an opportunity to improve the docs, though.

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@blairconrad's explanation is correct. Basically, dynamic messes up with extension methods. Just casting the value to object is probably the easiest fix.

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Casting to object - is genius! Thank you, guys.

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