IsolationFrameworksComparison.cs

//Moq
var lollipop = new Mock<ICandy>();
var shop =  new Mock<ICandyShop>();
shop.Setup(s => s.GetTopSellingCandy()).Returns(lollipop);
shop.Verify(s => s.BuyCandy(lollipop), Times.AtMostOnce());

//NSubstitude
var lollipop = Substitute.For<ICandy>();
var shop = Substitute.For<ICandyShop>();
shop.GetTopSellingCandy().Returns(lollipop);
shop.Received().BuyCandy(lollipop);

//FakeItEasy
var lollipop = A.Fake<ICandy>();
var shop = A.Fake<ICandyShop>();
A.CallTo(() => shop.GetTopSellingCandy()).Returns(lollipop);
A.CallTo(() => shop.BuyCandy(lollipop)).MustHaveHappened();