Mock HttpRequest in ASP.NET C# Controller

当我们需要对如下的Index 方法写单元测试的时候，我们需要mock HttpRequest对象。

public class DefaultController : Controller
{
    private IPlayer _player;

    public DefaultController (IPlayer player = null):base()
    {
        _player= player;
    }

    public PartialViewResult Index()
    {
        var viewModel = new PlayerViewModel();
        var token = Request.Headers["token"];
        if (token == null) 
        {
            viewModel.ErrorMessage = "Please log in first."
        }
        else
        {
            viewModel.Player = _player.GetLoggedInPlayer(token);      
        } 

        return PartialView("Index", viewModel); } 
}

通过如下方法，我们可以mock出ControllerContext。

public static ControllerContext GetControllerContext(ControllerBase controller)
{
　　var httpRequest = new HttpRequest("", "http://test.com", "");
　　var stringWriter = new StringWriter();
　　var httpResponse = new HttpResponse(stringWriter);
　　var httpContextMock = new HttpContext(httpRequest, httpResponse); // mock HttpContext
　　httpContextMock.Request.Headers["token"] = "fake_token_here";
　　return new ControllerContext(new HttpContextWrapper(httpContextMock), new RouteData(), controller);
}

并且在写单元测试的时候，通过如下方式把mock的ControllerContext赋值给DefaultController。

_defaultController.ControllerContext = ControllerContextMocks.GetControllerContext(_defaultController);