_types()         {             // NOTE: This is an *invalid* query, but it should be an *executable* query.              var query = @"                 query AQuery {                   __typename                   name                   pets {                     __typename                     name                     barks                     meows                   }                 }             ";              var expected = @"                 {                   ""__typename"": ""Person"",                   ""name"": ""John"",                   ""pets"": [                     { ""__typename"":  ""Cat"", ""name"": ""Garfield"", ""meows"": false },                     { ""__typename"":  ""Dog"", ""name"": ""Odie"", ""barks"": true }                   ]                 }             ";              AssertQuerySuccess(query, expected, root: _john, rules: Enumerable.Empty<IValidationRule>());         }          [Fact]         public void executes_u