Feature-Request: Enable calling original implementation if no stub is provided.

[winstondu]

Sometimes, I might just want to create a version of my concrete type that is the real object, except that the invocations of functions and the get/set of properties can be verified.

From a quick overview of the architecture, this seems totally feasible. This is because mocks of concrete types are created by Mockingbird via subclassing that concrete type.

Currently, whenever there is no stub of the desired/function/property provided for the mock class, fatalError(self.stubbingContext.failTest(for: invocation)) is called.

But we could also just use the actual implementation with just super call.

[andrewchang-bird]

Partial mocks is in the works :) Both passing the call to the superclass as well as proxying an object that conforms to the mocked type.