Implicit cast operator in ActionResult<bool> not working - asp.net-core

Question

I am following this guide to build my controllers. I do the following.
This is my controller:
// GET api/sth/{sthId}/isValid
[HttpGet("{sthId: int}/isValid")]
[ProducesResponseType(StatusCodes.Status200OK)]
[MyAuthorizeFilter]
public ActionResult<bool> Whatever(int sthId)
{
return this.myService.Whatever(sthId);
}
Theoretically, this should be converted to an Ok() ActionResult. However, If I write the following unit test:
[Fact]
public void Whatever()
{
this.myServiceMock.Setup(x => x.Whatever(It.IsAny<int>())).Returns(true);
-> I DEBUG HERE -> var result = this.myController.Whatever(1);
Assert.IsType<OkObjectResult>(result);
Assert.True((bool)result.Value);
}
I see that my result is an ActionResult<bool> indeed, whose Value is true as expected, but result.Result is null. So: no Ok action result whatsoever.
What am I missing? Do I have to write explicitly the return Ok() to get it? With the sentence
Implicit cast operators support the conversion of both T and ActionResult to ActionResult<T>. T converts to ObjectResult, which means return new ObjectResult(T); is simplified to return T;.
in the documentation I thought it was not necessary...?

Answer 1

The ActionResult<TValue> class:
wraps either an[sic] TValue instance or an ActionResult.
See also the source, its constructors assign either Value or Result, never both.
The MVC pipeline will assign a success status code to the response if no status code was explicitly set. But I can't find documentation for that claim.
This means the response as obtained in this test won't have a status code or OkActionResult anywhere. You can convert it to an ObjectResult, but that won't have a status code.

Answer 2

If you use something like swagger you will indeed get an OK from the server.
This happens to you because you dont perform an http request you simple call a method(your controller method) and you get a return type. You dont create a web server or something so no http status code is generated by .net core.
If you want to get status codes you should write test using http requests. Generally you could look up something like postman to perform your testing.