Faking Azure AD identity in ASP.NET Core unit tests

When testing ASP.NET Core controllers in application that uses Azure AD we need usually current user at least for some tests. As there is no authenticated user when unit testing, we need to create one by our own. This blog post shows how to create claims identity for ASP.NET Core unit tests.

To have Azure AD user available we have to create fake claims identity and fill it with claims that test expects. Then we create the instance of constructor and initiate controller and HTTP context. The latter one contains identity.

Consider the following controller action.

public IActionResult Index()
{
    var name = User.Identity.Name;
 
    // Do something with name
 
    return View();
}

Test like this will probably fail with exception as there is no code that deals with current user identity.

[Fact]
public void SampleTest()
{
    var controller = new HomeController();
 
    controller.Index();
}

Let’s organize typical claims identity with some claims to controller.

[Fact]
public void SampleTest()
{
    var user = new ClaimsPrincipal(new ClaimsIdentity(new Claim[]
    {
            new Claim(ClaimTypes.NameIdentifier, "SomeValueHere"),
            new Claim(ClaimTypes.Name, "gunnar@somecompany.com")
            // other required and custom claims
    }), "TestAuthentication");
 
    var controller = new HomeController();
    controller.ControllerContext = new ControllerContext()
    {
        HttpContext = new DefaultHttpContext { User = user }
    };
 
    controller.Index();
}

Now we have fake claims identity available and our controller will use this. When running this test in Visual Studio we can see that controller has current user now.

It is also possible to use factory classes for identity. In this case we have one class for production and this returns the current identity controller has. Another class is for testing and this class creates and returns fake identity. As I don’t see much benefit on using factories with no additional value I suggest to go with directly created fake identity. Creating the identity can be moved to some helper method in test class if it is needed in multiple tests.