A class property get wrongly mocked when used as parameter for arranging other class methods. The following sample demonstrates the scenario: class Foo { public string Prop{ get; set; } public void Bar(string val) { } } [TestMethod] public void Sample() { var sut = Mock.Create<Foo>(Behavior.CallOriginal); Mock.Arrange(() => sut.Bar(sut.Prop)).DoNothing(); }