Duplicate keys in JSON and fuzzing problem

[ferretdb-bot]

dvyukov/go-fuzz-corpus#3
golang/go#14750
golang/go#48298

Something like that might be needed in the future:

// check if j contains objects with duplicate keys that not handled by encoding/json yet:
// * https://github.com/dvyukov/go-fuzz-corpus/issues/3
// * https://github.com/golang/go/issues/14750
// * https://github.com/golang/go/issues/48298
{
	var o1 interface{}
	if err := json.Unmarshal([]byte(j), &o1); err != nil {
		t.Skip(err)
	}

	b, err := json.Marshal(o1)
	if err != nil {
		t.Skip(err)
	}

	var o2 interface{}
	if err := json.Unmarshal(b, &o2); err != nil {
		t.Skip(err)
	}

	if !reflect.DeepEqual(o1, o2) {
		t.Skip("j contains objects with duplicate keys that not handled by encoding/json yet")
	}
}