Connects to #1437, in that if DynamicProxy gives us a way to fake delegates, we would likely have to drop this support anyhow. And it would make our capabilities more consistent, since we cannot fake classes or interfaces that aren't visible to DynamicProxy.

1499 revealed that we cannot serialize fakes once they've been configured.

Also, if any call has been made to them and we serialize and deserialize the fake, the previously-made calls are lost. (Also note that some calls, such as a property set or get, implicitly configure the fake, so even that last statement is optimistic.)

I don't think there's any value in making the fakes binary serializable and can't imagine that anyone's using the ability in any meaningful way.

Inspired by Stack Overflow question How to pass more than 4 arguments to FakeItEasy Invokes()?.

I'd thought the "more advanced scenarios" line in the docs would've hinted at this, but it could be more clear. The particular question involved Invokes, but we should take a look at related articles, such as Specifying Return Values, which does explicitly call out the 4-argument limitation and workaround.

In https://github.com/FakeItEasy/FakeItEasy/pull/1491#discussion_r233072656, @blairconrad said:

As I hint at, this hack wouldn't be necessary if IFakeObjectCallRule didn't expose Apply. But it needs to in order for people to create their own rules.

But I don't think that IInterceptionListener.OnAfterCallIntercepted needs to be passed an object that has an Apply method; there's no need for OnAfterCallIntercepted to call Apply. I don't even know why it would need to call IsApplicable or NumberOfTimesToCall. Shall we explore changing this in a future major version? We could supply OnAfterCallIntercepted with a different interface that's a restricted version of IFakeObjectCallRule, or even remove the IFakeObjectCallRule parameter.

@thomaslevesque replied:

Seems like a good idea. I don't see any value in having the call rule available in OnAfterCallIntercepted, except for information purposes. Maybe we could just pass a string describing the rule, or just the type of the rule.

It could be faster!