create gesture recognizers on attach and dispose on detach to avoid leaks - #42076

It looks like this pull request may not have tests. Please make sure to add tests before merging. If you need an exemption to this rule, contact Hixie.

Reviewers: Read the Tree Hygiene page and make sure this patch meets those guidelines before LGTMing.

First of all, Welcome and thank you for contributing to flutter !

The change looks good, but we would like to have test to make sure no one break it in the future. Can you add a test for this change?

Thanks :)
Like I said on the description, I don't mind adding test, but I don't know how/what to test here. It's only internal stuff on the class that has moved and wasn't tested previously.
Can you explain me what kind of tests are expected ? I would gladly add them

Yes, it seems extreme hard to test this method.... Someone might have a better idea

I can only think of an indirect way of testing this

test('editale test', () {
    final TextSelectionDelegate delegate = FakeEditableTextState();
    final RenderEditable editable = RenderEditable(
      backgroundCursorColor: Colors.grey,
      selectionColor: Colors.black,
      textDirection: TextDirection.ltr,
      cursorColor: Colors.red,
      offset: ViewportOffset.zero(),
      textSelectionDelegate: delegate,
      text: const TextSpan(
        text: 'test',
        style: TextStyle(
          height: 1.0, fontSize: 10.0, fontFamily: 'Ahem',
        ),
      ),
      startHandleLayerLink: LayerLink(),
      endHandleLayerLink: LayerLink(),
      selection: const TextSelection(
        baseOffset: 0,
        extentOffset: 3,
        affinity: TextAffinity.upstream,
      ),
      onSelectionChanged: (_, __, ___) { },
    );
    final PipelineOwner owner = PipelineOwner(onNeedVisualUpdate: () { });
    // Implement CustomTestWidgetsFlutterBinding that implement a spy into
    // GestureBinding.instance.pointerRouter you can use TestWidgetsFlutterBinding
    // as template
    CustomTestWidgetsFlutterBinding.ensureInitialized();
    editable.attach(owner);
    // This should register pointer into GestureBinding.instance.pointerRouter.
    editable.handleEvent(const PointerDownEvent(), BoxHitTestEntry(editable, const Offset(10,10)));
    editable.detach();
    // Make sure GestureBinding.instance.pointerRouter is removed
    // ...
  });

When Rendereditable handle a pointer event it will use taprecognizer to register the pointer into GestureBinding.instance.pointerRouter.
In theory we can check GestureBinding.instance.pointerRouter is empty after rendereditable is detached. However, there is no public api to spy into what is in the tracked pointer in GestureBinding.instance.pointerRouter. What you can do is to override the GestureBinding that can spy into GestureBinding.instance.pointerRouter.

Let me know if any of the code above is unclear.

By the way, this test should live in https://github.com/flutter/flutter/blob/master/packages/flutter/test/rendering/editable_test.dart

@chunhtai ok I finally was able to make that test !! I was struggling to spy the GestureBinding. Let me know if it's ok

@chunhtai I have a problem, look like _GestureBindingSpy() have to be called before the test start, but if I do so all other tests are failing.
What I need is a setUp(() => _GestureBindingSpy()); but only for my test and not the other.
Is there a way to achieve this ? Or should I move my tests into it's own file (editable_gesture_test.dart) ? Let me know :)

I've push it on another file to be sure all the CI builds were green :) all good

@goderbauer I have made the changes, but look like some builds need to be restart (errors doesn't look like happening because of my changes)

Thank you again for the contribution @jaumard ! 🎉