How to mock a HttpResponse in Asp.NetCore controller?

Question

I am working on a Asp.NetCore application, and one of the controllers looks like this:

[HttpPost, Route("setCookies")]
public int SetCookies([FromBody] Dictionary<string, string> cookies)
{
    foreach (var cookie in cookies)
    {
        Response.Cookies.Append(cookie.Key, cookie.Value, new CookieOptions() { Path = "/", HttpOnly = true });
    }

    return 1;
}

And now I am trying to add unit test case for this controller.

After I create an instance of the controller by

var _controller = new Controller();

and call the method

_controller.SetCookies(<some parameter>);

It shows that Response is null.

I checked the metadate and it shows that Response is a readonly property in the abstract base class ControllerBase like this:

public HttpResponse Response { get; }

So, is there anyway to mock the Response property?

Answer 1

The request and response are associated with the controller's current HttpContext, which you will need to set via the ControllerContext when setting up the controller.

//...
//Arrange
HttpContext httpContext = new DefaultHttpContext();
//Controller needs a controller context 
var controllerContext = new ControllerContext() {
    HttpContext = httpContext,
};
//assign context to controller
var _controller = new MyController(){
    ControllerContext = controllerContext,
};

//Act
int actual = _controller.SetCookies(<some parameter>);

//...

The DefaultHttpContext used in the example above, will have a non-null empty request and response by default. This should give you access to the response to exercise your unit test as desired.