ASP.NET Core对Controller进行单元测试的完整步骤

我双手接过晶莹的雪花，想数一数它有几朵花瓣，谁知它到手上就不见了，变成了小水珠。

前言

单元测试对我们的代码质量非常重要。很多同学都会对业务逻辑或者工具方法写测试用例，但是往往忽略了对Controller层写单元测试。我所在的公司没见过一个对Controller写过测试的。今天来演示下如果对Controller进行单元测试。以下内容默认您对单元测试有所了解，比如如何mock一个接口。在这里多叨叨一句，面向接口的好处，除了能够快速的替换实现类（其实大部分接口不会有多个实现），最大的好处就是可以进行mock，可以进行单元测试。

测试Action

下面的Action非常简单，非常常见的一种代码。根据用户id去获取用户信息然后展示出来。下面看看如何对这个Action进行测试。

  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);
    }
   
  }

测试代码：

 [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);
      //对空参数进行assert
      Assert.ThrowsException<ArgumentNullException>(() => {
        var result = ctrl.UserInfo(null);
      });
      //对空参数进行assert
      Assert.ThrowsException<ArgumentNullException>(() => {
        var result = ctrl.UserInfo("");
      });

      var result = ctrl.UserInfo("1");
      Assert.IsNotNull(result);
      Assert.IsInstanceOfType(result, typeof(ViewResult));
    }

我们对一个Action进行测试主要的思路就是模拟各种入参，使测试代码能够到达所有的分支，并且Assert输出是否为空，是否为指定的类型等。

对ViewModel进行测试

我们编写Action的时候还会涉及ViewModel给视图传递数据，这部分也需要进行测试。修改测试用例，加入对ViewModel的测试代码：

 [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));
      //对viewModel进行assert
      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);
    }

对ViewData进行测试

我们编写Action的时候还会涉及ViewData给视图传递数据，这部分同样需要测试。修改Action代码，对ViewData进行赋值：

  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);
    }

修改测试用例，加入对ViewData的测试代码：

  [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);
      //对viewData进行assert
      Assert.IsTrue(vr.ViewData.ContainsKey("title"));
      var title = vr.ViewData["title"];
      Assert.AreEqual("user_info", title);
    }

对ViewBag进行测试

因为ViewBag事实上是ViewData的dynamic类型的包装，所以Action代码不用改，可以直接对ViewBag进行测试：

   [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);
      //对viewBag进行assert
      string title1 = ctrl.ViewBag.title;
      Assert.AreEqual("user_info", title1);
    }

设置HttpContext

我们编写Action的时候很多时候需要调用基类里的HttpContext，比如获取Request对象，获取Path，获取Headers等等，所以有的时候需要自己实例化HttpContext以进行测试。

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

对HttpContext.SignInAsync进行mock

我们使用ASP.NET Core框架进行登录认证的时候，往往使用HttpContext.SignInAsync进行认证授权，所以单元测试的时候也需要进行mock。下面是一个典型的登录Action，对密码进行认证后调用SignInAsync在客户端生成登录凭证，否则跳到登录失败页面。

  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其实个时扩展方法，SignInAsync其实最终是调用了IAuthenticationService里的SignInAsync方法。所以我们需要mock的就是IAuthenticationService接口，否者代码走到HttpContext.SignInAsync会提示找不到IAuthenticationService的service。而IAuthenticationService本身是通过IServiceProvider注入到程序里的，所以同时需要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);
    }

对HttpContext.AuthenticateAsync进行mock

HttpContext.AuthenticateAsync同样比较常用。这个扩展方法同样是在IAuthenticationService里，所以测试代码跟上面的SignInAsync类似，只是需要对AuthenticateAsync继续mock返回值success or fail。

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

      return Redirect("/login");
    }

测试用例：

    [TestMethod()]
    public async Task LoginTest1()
    {
      var authenticationService = new Mock<IAuthenticationService>();
      //设置AuthenticateAsync为success
      authenticationService.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);
      //设置AuthenticateAsync为fail
      authenticationService.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进行测试

我们写Controller的时候往往需要配合很多Filter使用，所以Filter的测试也很重要。下面演示下如何对Fitler进行测试。

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

      base.OnActionExecuting(context);
    }
  }

对Filter的测试最主要的是模拟ActionExecutingContext参数，以及其中的HttpContext等，然后对预期进行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("拒绝访问", 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);
    }

总结

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