How to get content value in Xunit when result returned in IActionResult type

I have a unit test project using Xunit and the method we are testing returns IActionResult.

I saw some people suggest using "NegotiatedContentResult" to get the content of the IActionResult but that doesn't work in Xunit.

So I wonder how to get the content value of an IActionResult in Xunit?

Test code example is provided below:

public void GetTest()
    {
        var getTest = new ResourcesController(mockDb);

        var result = getTest.Get("1");

        //Here I want to convert the result to my model called Resource and
        //compare the attribute Description like below.
        Resource r = ?? //to get the content value of the IActionResult

        Assert.Equal("test", r.Description);
    }

Does anyone know how to do this in XUnit?

Thanks!