如何使用fakeiteasy为包含对HttpContext调用的代码编写MSpec测试？

public ActionResult Add()
    {

        this.HttpContext.Items[\"pm-page-title\"] = \"Some title\";

        return this.View();
    }

// arrange
var sut = new SomeController();
sut.ControllerContext = A.Fake<ControllerContext>();
var fakeContext = A.Fake<HttpContextBase>();
A.CallTo(() => sut.ControllerContext.HttpContext).Returns(fakeContext);
A.CallTo(() => fakeContext.Items).Returns(new Hashtable());

// act
var actual = sut.Add();

// assert
Assert.AreEqual(\"Some title\", (string)fakeContext.Items[\"pm-page-title\"]);