public void Execute_ShouldExecuteActionOnExtensions()
{
var firstExtension = new Mock<ICustomExtension>();
var secondExtension = new Mock<ICustomExtension>();
this.testee.Execute(new List<ICustomExtension> { firstExtension.Object, secondExtension.Object }, this.executableContext.Object);
firstExtension.Verify(x => x.SomeMethod(It.IsAny<object>()));
secondExtension.Verify(x => x.SomeMethod(It.IsAny<object>()));
}