I've discussed with @LongCatIsLooong, who proposed that we could also set the view size to be zero.
This also reflects the actual goal of the original issue, that is to ensure widgets to not crash in a 0x0 view (the warmup frame). Specifically for DropdownMenu, it would be something like this:

  testWidgets('DropdownMenu does not crash at zero area', (WidgetTester tester) async {
    tester.view.physicalSize = Size.zero;
    final TextEditingController controller = TextEditingController(text: 'I');
    addTearDown(controller.dispose);

    await tester.pumpWidget(
      MaterialApp(
        home: Scaffold(
          body: Center(
            child: DropdownMenu<TestMenu>(
              dropdownMenuEntries: menuChildren,
              controller: controller,
            ),
          ),
        ),
      ),
    );
    expect(tester.getSize(find.byType(DropdownMenu<TestMenu>)), Size.zero);
    controller.selection = const TextSelection.collapsed(offset: 0);
    await tester.pump();
    expect(find.byType(MenuItemButton), findsWidgets);
  });

Notable points:

• This snippet now set the physicalSize to be zero to align more closely to the original issue.
• The controller is needed for this widget specifically because a zero-sized widget can't be tapped.
• The target widget should have a 0x0 size even without the SizedBox.shrink. Nevertheless we can still verify its size.
• This snippet does not verify the overlay's size, partly because I find no easy way (no public accessor to the overlay layer), but also that the overlay stack is not surrounded by anything there should be minimum possibility of human error; being able to render it in a 0x0 view should be enough.

Either this way or the previous way (with SizedBox.shrink) should be ok for simpler widgets without overlays (so no need to change existing tests or PRs), but this one is probably better for overlays. What do you think?

If I understand correctly, it is meaningless to make any spatial interaction with a widget that occupies a zero area of the screen, and people cannot make any spatial interaction with the widget when starting up the framework in a 0x0 environment, as the original purpose of the issue had been stated in #6537 (comment).

If I understand correctly, it is meaningless to make any spatial interaction with a widget that occupies a zero area of the screen, and people cannot make any spatial interaction with the widget when starting up the framework in a 0x0 environment, as the original purpose of the issue had been stated in #6537 (comment).

The idea is not to test whether a zero-size widget is interactable, but to verify that the content in the pop-up can also be rendered in a zero-size constraints, which matters because:

• Since a controller option is publicly available, it is legal and possible for developers to show a pop up in the same way as our test, i.e. the pop up doesn't have to be triggered by a gesture, which is worth verifying.
• Although the 0x0 case isn't interactable, constraints of non-zero small constraints (such as 4x4 pixels) are interactable, which are worth verifying.

@dkwingsmt I see that you approved my changes. Do you want me to apply these changes: #174809 (comment)? Or what?

@ahmedsameha1 Sorry I didn't meant to approve it. Yes, can you apply the change in the comment?

autosubmit label was removed for flutter/flutter/174809, because - The status or check suite Windows framework_tests_libraries has failed. Please fix the issues identified (or deflake) before re-applying this label.

• The status or check suite Mac framework_tests_impeller has failed. Please fix the issues identified (or deflake) before re-applying this label.

autosubmit label was removed for flutter/flutter/174809, because - The status or check suite Windows framework_tests_libraries has failed. Please fix the issues identified (or deflake) before re-applying this label.

• The status or check suite Mac framework_tests_impeller has failed. Please fix the issues identified (or deflake) before re-applying this label.

Hi @ahmedsameha1, can you resolve the merge conflicts?