Mocking IPrincipal in ASP.NET Core

The controller’s User is accessed through the HttpContext of the controller. The latter is stored within the ControllerContext.

The easiest way to set the user is by assigning a different HttpContext with a constructed user. We can use DefaultHttpContext for this purpose, that way we don’t have to mock everything. Then we just use that HttpContext within a controller context and pass that to the controller instance:

var user = new ClaimsPrincipal(new ClaimsIdentity(new Claim[]
{
    new Claim(ClaimTypes.Name, "example name"),
    new Claim(ClaimTypes.NameIdentifier, "1"),
    new Claim("custom-claim", "example claim value"),
}, "mock"));

var controller = new SomeController(dependencies…);
controller.ControllerContext = new ControllerContext()
{
    HttpContext = new DefaultHttpContext() { User = user }
};

When creating your own ClaimsIdentity, make sure to pass an explicit authenticationType to the constructor. This makes sure that IsAuthenticated will work correctly (in case you use that in your code to determine whether a user is authenticated).

In previous versions you could have set User directly on the controller, which made for some very easy unit tests.

If you look at the source code for ControllerBase you will notice that the User is extracted from HttpContext.

/// <summary>
/// Gets the <see cref="ClaimsPrincipal"/> for user associated with the executing action.
/// </summary>
public ClaimsPrincipal User => HttpContext?.User;

and the controller accesses the HttpContext via ControllerContext

/// <summary>
/// Gets the <see cref="Http.HttpContext"/> for the executing action.
/// </summary>
public HttpContext HttpContext => ControllerContext.HttpContext;

You will notice that these two are read only properties. The good news is that ControllerContext property allows for setting it's value so that will be your way in.

So the target is to get at that object. In Core HttpContext is abstract so it is a lot easier to mock.

Assuming a controller like

public class MyController : Controller {
    IMyContext _context;

    public MyController(IMyContext context) {
        _context = context;
    }

    public IActionResult Index() {
        SettingsViewModel svm = _context.MySettings(User.Identity.Name);
        return View(svm);
    }

    //...other code removed for brevity 
}

Using Moq, a test could look like this

public void Given_User_Index_Should_Return_ViewResult_With_Model() {
    //Arrange 
    var username = "FakeUserName";
    var identity = new GenericIdentity(username, "");

    var mockPrincipal = new Mock<ClaimsPrincipal>();
    mockPrincipal.Setup(x => x.Identity).Returns(identity);
    mockPrincipal.Setup(x => x.IsInRole(It.IsAny<string>())).Returns(true);

    var mockHttpContext = new Mock<HttpContext>();
    mockHttpContext.Setup(m => m.User).Returns(mockPrincipal.Object);

    var model = new SettingsViewModel() {
        //...other code removed for brevity
    };

    var mockContext = new Mock<IMyContext>();
    mockContext.Setup(m => m.MySettings(username)).Returns(model);

    var controller = new MyController(mockContext.Object) {
        ControllerContext = new ControllerContext {
            HttpContext = mockHttpContext.Object
        }
    };

    //Act
    var viewResult = controller.Index() as ViewResult;

    //Assert
    Assert.IsNotNull(viewResult);
    Assert.IsNotNull(viewResult.Model);
    Assert.AreEqual(model, viewResult.Model);
}

There is also the possibility to use the existing classes, and mock only when needed.

var user = new Mock<ClaimsPrincipal>();
_controller.ControllerContext = new ControllerContext
{
    HttpContext = new DefaultHttpContext
    {
        User = user.Object
    }
};

In my case, I needed to make use of Request.HttpContext.User.Identity.IsAuthenticated, Request.HttpContext.User.Identity.Name and some business logic sitting outside of the controller. I was able to use a combination of Nkosi's, Calin's and Poke's answer for this:

var identity = new Mock<IIdentity>();
identity.SetupGet(i => i.IsAuthenticated).Returns(true);
identity.SetupGet(i => i.Name).Returns("FakeUserName");

var mockPrincipal = new Mock<ClaimsPrincipal>();
mockPrincipal.Setup(x => x.Identity).Returns(identity.Object);

var mockAuthHandler = new Mock<ICustomAuthorizationHandler>();
mockAuthHandler.Setup(x => x.CustomAuth(It.IsAny<ClaimsPrincipal>(), ...)).Returns(true).Verifiable();

var controller = new MyController(...);

var mockHttpContext = new Mock<HttpContext>();
mockHttpContext.Setup(m => m.User).Returns(mockPrincipal.Object);

controller.ControllerContext = new ControllerContext();
controller.ControllerContext.HttpContext = new DefaultHttpContext()
{
    User = mockPrincipal.Object
};

var result = controller.Get() as OkObjectResult;
//Assert results

mockAuthHandler.Verify();

Mocking IPrincipal in ASP.NET Core

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