單元測試對我們的代碼質量非常重要。很多同學都會對業務邏輯或者工具方法寫測試用例，但是往往忽略了對Controller層寫單元測試。我所在的公司沒見過一個對Controller寫過測試的。今天來演示下如果對Controller進行單元測試。以下內容默認您對單元測試有所了解，比如如何mock一個接口。在這里多叨叨一句，面向接口的好處，除了能夠快速的替換實現類（其實大部分接口不會有多個實現），最大的好處就是可以進行mock，可以進行單元測試。

測試Action

下面的Action非常簡單，非常常見的一種代碼。根據用戶id去獲取用戶信息然后展示出來。下面看看如何對這個Action進行測試。

public class UserController : Controller{private readonly IUserService _userService;public UserController(IUserService userService){_userService = userService;}public IActionResult UserInfo(string userId){if (string.IsNullOrEmpty(userId)){throw new ArgumentNullException(nameof(userId));}var user = _userService.Get(userId);return View(user);}}

測試代碼：

[TestMethod()]public void UserInfoTest(){var userService = new Mock<IUserService>();userService.Setup(s => s.Get(It.IsAny<string>())).Returns(new User());var ctrl = new UserController(userService.Object);//對空參數進行assertAssert.ThrowsException<ArgumentNullException>(() => {var result = ctrl.UserInfo(null);});//對空參數進行assertAssert.ThrowsException<ArgumentNullException>(() => {var result = ctrl.UserInfo("");});var result = ctrl.UserInfo("1");Assert.IsNotNull(result);Assert.IsInstanceOfType(result, typeof(ViewResult));}

我們對一個Action進行測試主要的思路就是模擬各種入參，使測試代碼能夠到達所有的分支，并且Assert輸出是否為空，是否為指定的類型等。

對ViewModel進行測試

我們編寫Action的時候還會涉及ViewModel給視圖傳遞數據，這部分也需要進行測試。修改測試用例，加入對ViewModel的測試代碼：

[TestMethod()]public void UserInfoTest(){var userService = new Mock<IUserService>();userService.Setup(s => s.Get(It.IsAny<string>())).Returns(new User(){Id = "x"}) ;var ctrl = new UserController(userService.Object);Assert.ThrowsException<ArgumentNullException>(() => {var result = ctrl.UserInfo(null);});Assert.ThrowsException<ArgumentNullException>(() => {var result = ctrl.UserInfo("");});var result = ctrl.UserInfo("1");Assert.IsNotNull(result);Assert.IsInstanceOfType(result, typeof(ViewResult));//對viewModel進行assertvar vr = result as ViewResult;Assert.IsNotNull(vr.Model);Assert.IsInstanceOfType(vr.Model, typeof(User));var user = vr.Model as User;Assert.AreEqual("x", user.Id);}

對ViewData進行測試

我們編寫Action的時候還會涉及ViewData給視圖傳遞數據，這部分同樣需要測試。修改Action代碼，對ViewData進行賦值：

public IActionResult UserInfo(string userId){if (string.IsNullOrEmpty(userId)){throw new ArgumentNullException(nameof(userId));}var user = _userService.Get(userId);ViewData["title"] = "user_info";return View(user);}

修改測試用例，加入對ViewData的測試代碼：

[TestMethod()]public void UserInfoTest(){var userService = new Mock<IUserService>();userService.Setup(s => s.Get(It.IsAny<string>())).Returns(new User(){Id = "x"}) ;var ctrl = new UserController(userService.Object);Assert.ThrowsException<ArgumentNullException>(() => {var result = ctrl.UserInfo(null);});Assert.ThrowsException<ArgumentNullException>(() => {var result = ctrl.UserInfo("");});var result = ctrl.UserInfo("1");Assert.IsNotNull(result);Assert.IsInstanceOfType(result, typeof(ViewResult));var vr = result as ViewResult;Assert.IsNotNull(vr.Model);Assert.IsInstanceOfType(vr.Model, typeof(User));var user = vr.Model as User;Assert.AreEqual("x", user.Id);//對viewData進行assertAssert.IsTrue(vr.ViewData.ContainsKey("title"));var title = vr.ViewData["title"];Assert.AreEqual("user_info", title);}

對ViewBag進行測試

因為ViewBag事實上是ViewData的dynamic類型的包裝，所以Action代碼不用改，可以直接對ViewBag進行測試：

[TestMethod()]public void UserInfoTest(){var userService = new Mock<IUserService>();userService.Setup(s => s.Get(It.IsAny<string>())).Returns(new User(){Id = "x"}) ;var ctrl = new UserController(userService.Object);Assert.ThrowsException<ArgumentNullException>(() => {var result = ctrl.UserInfo(null);});Assert.ThrowsException<ArgumentNullException>(() => {var result = ctrl.UserInfo("");});var result = ctrl.UserInfo("1");Assert.IsNotNull(result);Assert.IsInstanceOfType(result, typeof(ViewResult));var vr = result as ViewResult;Assert.IsNotNull(vr.Model);Assert.IsInstanceOfType(vr.Model, typeof(User));var user = vr.Model as User;Assert.AreEqual("x", user.Id);Assert.IsTrue(vr.ViewData.ContainsKey("title"));var title = vr.ViewData["title"];Assert.AreEqual("user_info", title);//對viewBag進行assertstring title1 = ctrl.ViewBag.title;Assert.AreEqual("user_info", title1);}

設置HttpContext

我們編寫Action的時候很多時候需要調用基類里的HttpContext，比如獲取Request對象，獲取Path，獲取Headers等等，所以有的時候需要自己實例化HttpContext以進行測試。

var ctrl = new AccountController();ctrl.ControllerContext = new ControllerContext();ctrl.ControllerContext.HttpContext = new DefaultHttpContext();

對HttpContext.SignInAsync進行mock

我們使用ASP.NET Core框架進行登錄認證的時候，往往使用HttpContext.SignInAsync進行認證授權，所以單元測試的時候也需要進行mock。下面是一個典型的登錄Action，對密碼進行認證后調用SignInAsync在客戶端生成登錄憑證，否則跳到登錄失敗頁面。

public async Task<IActionResult> Login(string password){if (password == "123"){var claims = new List<Claim>{new Claim("UserName","x")};var authProperties = new AuthenticationProperties{};var claimsIdentity = new ClaimsIdentity(claims, CookieAuthenticationDefaults.AuthenticationScheme);await HttpContext.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme,new ClaimsPrincipal(claimsIdentity),authProperties);return Redirect("login_success");}return Redirect("login_fail");}

HttpContext.SignInAsync其實個時擴展方法，SignInAsync其實最終是調用了IAuthenticationService里的SignInAsync方法。所以我們需要mock的就是IAuthenticationService接口，否者代碼走到HttpContext.SignInAsync會提示找不到IAuthenticationService的service。而IAuthenticationService本身是通過IServiceProvider注入到程序里的，所以同時需要mock接口IServiceProvider。

[TestMethod()]public async Task LoginTest(){var ctrl = new AccountController();var authenticationService = new Mock<IAuthenticationService>();var sp = new Mock<IServiceProvider>();sp.Setup(s => s.GetService(typeof(IAuthenticationService))).Returns(() => {return authenticationService.Object;});ctrl.ControllerContext = new ControllerContext();ctrl.ControllerContext.HttpContext = new DefaultHttpContext();ctrl.ControllerContext.HttpContext.RequestServices = sp.Object;var result = await ctrl.Login("123");Assert.IsNotNull(result);Assert.IsInstanceOfType(result, typeof(RedirectResult));var rr = result as RedirectResult;Assert.AreEqual("login_success", rr.Url);result = await ctrl.Login("1");Assert.IsNotNull(result);Assert.IsInstanceOfType(result, typeof(RedirectResult));rr = result as RedirectResult;Assert.AreEqual("login_fail", rr.Url);}

對HttpContext.AuthenticateAsync進行mock

HttpContext.AuthenticateAsync同樣比較常用。這個擴展方法同樣是在IAuthenticationService里，所以測試代碼跟上面的SignInAsync類似，只是需要對AuthenticateAsync繼續mock返回值success or fail。

public async Task<IActionResult> Login(){if ((await HttpContext.AuthenticateAsync()).Succeeded){return Redirect("/home");}return Redirect("/login");}

測試用例：

[TestMethod()]public async Task LoginTest1(){var authenticationService = new Mock<IAuthenticationService>();//設置AuthenticateAsync為successauthenticationService.Setup(s => s.AuthenticateAsync(It.IsAny<HttpContext>(), It.IsAny<string>())).ReturnsAsync(AuthenticateResult.Success(new AuthenticationTicket(new System.Security.Claims.ClaimsPrincipal(), "")));var sp = new Mock<IServiceProvider>();sp.Setup(s => s.GetService(typeof(IAuthenticationService))).Returns(() => {return authenticationService.Object;});var ctrl = new AccountController();ctrl.ControllerContext = new ControllerContext();ctrl.ControllerContext.HttpContext = new DefaultHttpContext();ctrl.ControllerContext.HttpContext.RequestServices = sp.Object;var act = await ctrl.Login();Assert.IsNotNull(act);Assert.IsInstanceOfType(act, typeof(RedirectResult));var rd = act as RedirectResult;Assert.AreEqual("/home", rd.Url);//設置AuthenticateAsync為failauthenticationService.Setup(s => s.AuthenticateAsync(It.IsAny<HttpContext>(), It.IsAny<string>())).ReturnsAsync(AuthenticateResult.Fail(""));act = await ctrl.Login();Assert.IsNotNull(act);Assert.IsInstanceOfType(act, typeof(RedirectResult));rd = act as RedirectResult;Assert.AreEqual("/login", rd.Url);}

Filter進行測試

我們寫Controller的時候往往需要配合很多Filter使用，所以Filter的測試也很重要。下面演示下如何對Fitler進行測試。

public class MyFilter: ActionFilterAttribute{public override void OnActionExecuting(ActionExecutingContext context){if (context.HttpContext.Request.Path.Value.Contains("/abc/")){context.Result = new ContentResult() {Content = "拒絕訪問"};}base.OnActionExecuting(context);}}

對Filter的測試最主要的是模擬ActionExecutingContext參數，以及其中的HttpContext等，然后對預期進行Assert。

[TestMethod()]public void OnActionExecutingTest(){var filter = new MyFilter();var actContext = new ActionContext(new DefaultHttpContext(),new RouteData(), new ActionDescriptor());actContext.HttpContext.Request.Path = "/abc/123";var listFilters = new List<IFilterMetadata>();var argDict = new Dictionary<string, object>();var actExContext = new ActionExecutingContext(actContext ,listFilters ,argDict ,new AccountController());filter.OnActionExecuting(actExContext);Assert.IsNotNull(actExContext.Result);Assert.IsInstanceOfType(actExContext.Result, typeof(ContentResult));var cr = actExContext.Result as ContentResult;Assert.AreEqual("拒絕訪問", cr.Content);actContext = new ActionContext(new DefaultHttpContext(), new RouteData(), new ActionDescriptor());actContext.HttpContext.Request.Path = "/1/123";listFilters = new List<IFilterMetadata>();argDict = new Dictionary<string, object>();actExContext = new ActionExecutingContext(actContext,listFilters,argDict,new AccountController());filter.OnActionExecuting(actExContext);Assert.IsNull(actExContext.Result);}

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