Unit Test Controller mocking ISession

Question

I want to Unit Test my Controller, but I'm having issues reading values from HttpContext.Session.
I want to mock this piece from my Controller: HttpContext.Session.Get<int>(Foo)

With Mock HttpContext for unit testing a .NET core MVC controller? and How to mock Session Object in asp net core I was able to come to the following solution:

My Test:

public void GetFoos_AllGood_ReturnList()
{
  //Arrange
  Mock<ISession> sessionMock = new Mock<ISession>();
  var fooSessionValue = new byte[0];

  Web.Controllers.FooController fooController = new Web.Controllers.FooController();
  fooController.ControllerContext.HttpContext = new DefaultHttpContext();
  fooController.ControllerContext.HttpContext.Request.Headers["Foo"] = 0;

  Mock<IServiceCollection> mock = new Mock<IServiceCollection>();
  mock.Object.AddSession(); // Tried this, but failed

  //Setup
  sessionMock.Setup(_ => _.Set("Foo", It.IsAny<byte[]>())).Callback<string, byte[]>((k, v) => fooSessionValue = v);
  sessionMock.Setup(_ => _.TryGetValue("Foo", out fooSessionValue)).Returns(true);
  mockWebDataManager.Setup(b => b.GetFoos(It.IsAny<FooArgs>())).Returns(new FooResult() { Foos = new List<Foo>() });

  //Act
  var result = fooController.GetFoos() as JsonResult;

  //Assert
  Assert.NotNull(result);
  Assert.Equal(200, result.StatusCode);
}

My Controller:

internal virtual DataArgs CreateArgs()
{
  return new FooArgs
  {
     HttpContext.Session.Get<int>(Foo) // I want to Mock this value    
  };
}

[HttpGet]
public IActionResult GetFoos()
{
  FooArgs args = CreateArgs();
  ...
}

Answer 1

If anyone faces the same issue one day, here you go:

public void GetFoos_AllGood_ReturnList()
{
  //Arrange
  Mock<ISession> sessionMock = new Mock<ISession>();

  Web.Controllers.FooController fooController = new Web.Controllers.FooController();
  fooController.ControllerContext.HttpContext = new DefaultHttpContext();
  fooController.ControllerContext.HttpContext.Request.Headers["Foo"] = 0; 
  fooController.ControllerContext.HttpContext.Session = sessionMock.Object;

  //Act
  var result = fooController.GetFoos() as JsonResult;

  //Assert
  Assert.NotNull(result);
}