Have the following assignment. Have to create an unit test using c#

controller File.cs

public class API_FIRM_LINKController : ODataController

private Entities db =new Entities();

file.cs

public SingleResult GetAPI_FIRM_LINK([FromODataUri] Guid key) {

return SingleResult.Create(db.API_FIRM_LINK.Where(aPI_FIRM_LINK => aPI_FIRM_LINK.ApiFirmLInkId == key ));

}

Here is where I need help with it : I have some work done but needs work. Thanks

//Arrange

var controller = new API_FIRM_LINK();

//ACT

var result = controller.GetAPI_FIRM_LINK();

//ASSERT

Assert.IsNotNull(result);

Console.Write(result);