Resolving and piping the view ID through the WidgetController and the TestPointer so that clicks wind up on the right view #178941

mattkae · 2025-11-21T19:38:57Z

What's new?

While coming up with a scheme for testing multi-window, I realize that issuing taps in testWidgets across views was not working because the view was always being set to 0
The fix is to resolve the view when we can, and provide an optional view in the other methods

Pre-launch Checklist

I read the [Contributor Guide] and followed the process outlined there for submitting PRs.
I read the [Tree Hygiene] wiki page, which explains my responsibilities.
I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
I signed the [CLA].
I listed at least one issue that this PR fixes in the description above.
I updated/added relevant documentation (doc comments with ///).
I added new tests to check the change I am making, or this PR is [test-exempt].
I followed the [breaking change policy] and added [Data Driven Fixes] where supported.
All existing and new tests are passing.

flutter-dashboard · 2025-11-21T19:39:00Z

It looks like this pull request may not have tests. Please make sure to add tests or get an explicit test exemption before merging.

If you are not sure if you need tests, consider this rule of thumb: the purpose of a test is to make sure someone doesn't accidentally revert the fix. Ask yourself, is there anything in your PR that you feel it is important we not accidentally revert back to how it was before your fix?

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Code Review

This pull request adds viewId parameters to various testing APIs to support multi-window testing. The changes correctly pipe the viewId through TestPointer and WidgetController methods, which is a good improvement for multi-view testing scenarios. I've found a couple of issues: one method has an unused parameter, and another has a bug where the view ID is not correctly resolved from the provided Finder. The rest of the changes look solid.

packages/flutter_test/lib/src/controller.dart

… TestPointer so that clicks wind up on the right view

packages/flutter_test/lib/src/controller.dart

knopp · 2025-11-24T15:34:17Z

I am wondering a bit whether viewId couldn't be a property on TestPointer instead of being specified in each method?

…ter into flutter_test_view_tapping

mattkae · 2025-11-24T20:10:08Z

@loic-sharma In tests, I get:

10:04 +11784 ~34 -6: /b/s/w/ir/x/w/flutter/packages/flutter/test/gestures/pointer_router_test.dart: Supports re-entrant cancellation [E]
  Binding has not yet been initialized.
  The "instance" getter on the WidgetsBinding binding mixin is only available once that binding has been initialized.
  Typically, this is done by calling "WidgetsFlutterBinding.ensureInitialized()" or "runApp()" (the latter calls the former). Typically this call is done in the "void main()" method. The "ensureInitialized" method is idempotent; calling it multiple times is not harmful. After calling that method, the "instance" getter will return the binding.
  In a test, one can call "TestWidgetsFlutterBinding.ensureInitialized()" as the first line in the test's "main()" method to initialize the binding.
  If WidgetsBinding is a custom binding mixin, there must also be a custom binding class, like WidgetsFlutterBinding, but that mixes in the selected binding, and that is the class that must be constructed before using the "instance" getter.
  package:flutter/src/foundation/binding.dart 314:9  BindingBase.checkInstance.<fn>
  package:flutter/src/foundation/binding.dart 401:6  BindingBase.checkInstance
  package:flutter/src/widgets/binding.dart 477:53    WidgetsBinding.instance
  package:flutter_test/src/test_pointer.dart 138:46  TestPointer.down
  test/gestures/pointer_router_test.dart 43:27       main.<fn>

I think others were using 0 there because it was a safe-ish value. Do I ensureInitialized() or should I just put it back to 0?

loic-sharma · 2025-11-24T21:42:07Z

EDIT: Updated after more digging.

@mattkae What do you think of:

Update TestPointer to switch from WidgetsFlutterBinding.instance to TestWidgetsFlutterBinding.instance
Update those test/gestures/pointer_router_test.dart tests to call TestWidgetsFlutterBinding.ensureInitialized().

I am wondering a bit whether viewId couldn't be a property on TestPointer instead of being specified in each method?

This might make it less convenient to write a test for a pointer interaction that spans multiple views. For example, I might want to check the content of two tooltips in two separate views. Let me ask the team for additional opinions though!

…ntroller_test

chunhtai

overall lgtm, just a minor comment

packages/flutter_test/lib/src/controller.dart

packages/flutter_test/lib/src/test_pointer.dart

loic-sharma

Looks good to me once pending comments are addressed!

…er and the TestPointer so that clicks wind up on the right view (flutter/flutter#178941)

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… TestPointer so that clicks wind up on the right view (flutter#178941) ## What's new? - While coming up with a scheme for testing multi-window, I realize that issuing taps in `testWidgets` across views was not working because the view was always being set to `0` - The fix is to resolve the view when we can, and provide an optional view in the other methods ## Pre-launch Checklist - [x] I read the [Contributor Guide] and followed the process outlined there for submitting PRs. - [x] I read the [Tree Hygiene] wiki page, which explains my responsibilities. - [x] I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement]. - [x] I signed the [CLA]. - [x] I listed at least one issue that this PR fixes in the description above. - [x] I updated/added relevant documentation (doc comments with `///`). - [x] I added new tests to check the change I am making, or this PR is [test-exempt]. - [x] I followed the [breaking change policy] and added [Data Driven Fixes] where supported. - [x] All existing and new tests are passing.

mattkae requested review from justinmc, knopp and loic-sharma November 21, 2025 19:38

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… TestPointer so that clicks wind up on the right view

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Using FlutterView instead of an integer view id

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mattkae requested a review from loic-sharma November 24, 2025 15:21

Merge branch 'master' into flutter_test_view_tapping

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mattkae added 3 commits November 24, 2025 13:35

Reset hitTestOnBinding

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Merge branch 'flutter_test_view_tapping' of github.com:canonical/flut…

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…ter into flutter_test_view_tapping

Fix dart analyze

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Using TestWidgetsFlutterBinding

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github-actions bot added f: routes Navigator, Router, and related APIs. f: gestures flutter/packages/flutter/gestures repository. labels Nov 25, 2025

mattkae added 4 commits November 25, 2025 09:56

FlutterView should optionally resolve

dc2601b

Dart format

3549937

Adding TestWidgetsFlutterBinding.ensureInitialized for live_widget_co…

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…ntroller_test

Defaulting to viewId zero

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Use WidgetsBinding

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mattkae added 4 commits November 26, 2025 09:08

Pull request feedback

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Remove unused import

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Merge branch 'master' into flutter_test_view_tapping

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Merge branch 'master' into flutter_test_view_tapping

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mattkae added this pull request to the merge queue Dec 1, 2025

Merged via the queue into flutter:master with commit a99fb28 Dec 1, 2025
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a99fb2861 Resolving and piping the view ID through the WidgetControll…

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…er and the TestPointer so that clicks wind up on the right view (flutter/flutter#178941)

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Roll Flutter from 05d6005dd85c to 14063cfd0bc1 (26 revisions) flutter/packages#10548

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a99fb2861 Resolving and piping the view ID through the WidgetControll…

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…er and the TestPointer so that clicks wind up on the right view (flutter/flutter#178941)

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Roll Flutter from 05d6005dd85c to 271eb460369e (27 revisions) flutter/packages#10550

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a99fb2861 Resolving and piping the view ID through the WidgetControll…

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…er and the TestPointer so that clicks wind up on the right view (flutter/flutter#178941)

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ExpansionTile throws: Announce message 'viewId' property must be a FlutterViewId #179563

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Resolving and piping the view ID through the WidgetController and the TestPointer so that clicks wind up on the right view #178941

Resolving and piping the view ID through the WidgetController and the TestPointer so that clicks wind up on the right view #178941

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Resolving and piping the view ID through the WidgetController and the TestPointer so that clicks wind up on the right view #178941

Resolving and piping the view ID through the WidgetController and the TestPointer so that clicks wind up on the right view #178941

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mattkae commented Nov 21, 2025

What's new?

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loic-sharma commented Nov 24, 2025 •

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