Fluent API allows setting the return value and throwing an exception at the same time

[stakx]

This is currently (as of version 4.9.0) possible:

var mock = new Mock<object>();
mock.Setup(m => m.ToString())
    .Returns(() => "some string")
    .Callback(() => { })
    .Throws<Exception>();

This obviously doesn't make any sense at all: A regular method cannot return a value and throw an exception at the same time, so this shouldn't be possible in Moq either.

[stakx]

This will be tracked in #668 along with some other closely related issues.