Get data from JsonResult

The code is in ASP.NET Core. MVC controller returns Json(someData). I am trying to retrieve the data in the Unit test. The best I can do is to have

string data = JsonConvert.SerializeObject(jsonResult.Value);

and then compare the string. But I would prefer to get an object or an array to be able to do some more specific comparisons. Interesting, under debugger I can see that jsonResult.Value is of type Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable<MyType> and there is even Results View that warns not to expand it or else; and if I expand it, I get exactly what I want! In my case it is a 4-element array of MyType objects. However, if I do something like from i in jsonResult.Value select i I get an error

Could not find an implementation of the query pattern for source type 'object'. 
'Select' not found

I hope there is a better way than comparing a JSON string!