[ Widget Preview ] Add `--machine` mode #173654

bkonyi · 2025-08-12T21:30:24Z

Currently only outputs a single event with information about where the widget preview environment is served from:

[{"event":"widget_preview.started","params":{"url":"http://localhost:61383"}}]

Fixes #173545

Currently only outputs a single event with information about where the widget preview environment is served from: `[{"event":"widget_preview.started","params":{"url":"http://localhost:61383"}}]` Fixes #173545

gemini-code-assist

Code Review

This pull request adds a --machine mode to the widget-preview command, allowing it to output structured JSON events. The changes involve adding a new WidgetPreviewMachineAwareLogger to handle the conditional logging, updating the command to accept the --machine flag, and adding an integration test for the new mode.

My review focuses on the implementation of WidgetPreviewMachineAwareLogger. I've found a critical syntax error that would prevent compilation and suggested a refactoring to simplify the class and improve maintainability by better leveraging its superclass.

packages/flutter_tools/lib/src/commands/widget_preview.dart

DanTup

Some nits that you're free to ignore, but lgtm - thanks!

DanTup · 2025-08-12T22:36:50Z

packages/flutter_tools/test/integration.shard/widget_preview_machine_test.dart

+    bool useWebServer = false,
+  }) async {
+    expect(expectedEvents, isNotEmpty);
+    var i = 0;


nit: given the distance to where this variable is used is more than a few lines, maybe make the name more descriptive?

DanTup · 2025-08-12T22:39:15Z

packages/flutter_tools/test/integration.shard/widget_preview_machine_test.dart

+
+  group('flutter widget-preview start --machine', () {
+    testWithoutContext('launches in browser', () async {
+      await runWidgetPreviewMachineMode(expectedEvents: launchEvents);


It might be worth checking the event definitely has a valid URL in the args.

jyameo

lgtm!

LongCatIsLooong · 2025-08-13T21:06:27Z

The tree is red on this PR and it doesn't look like a flake:

flutter/packages/flutter_tools/lib/src/commands/widget_preview.dart:261:34: Error: The getter 'FlutterGlobalOptions' isn't defined for the type 'WidgetPreviewStartCommand'.
 - 'WidgetPreviewStartCommand' is from 'package:flutter_tools/src/commands/widget_preview.dart' ('flutter/packages/flutter_tools/lib/src/commands/widget_preview.dart').
Try correcting the name to the name of an existing getter, or defining a getter or field named 'FlutterGlobalOptions'.
    final bool machine = boolArg(FlutterGlobalOptions.kMachineFlag);
                                 ^^^^^^^^^^^^^^^^^^^^

DanTup · 2025-08-13T21:12:35Z

I think because the other change (1eb2f68) removed the import for ../runner/flutter_command_runner.dart. (Edit: I see a fix in the queue - #173731)

I thought the merge queue would've prevented this kind of issue by running the bots on each change based on the parent they'll be merged with? Does it not work that way?

bkonyi · 2025-08-13T21:18:41Z

Correct. There was some unfortunate timing between two PRs landing as one of them removed the import and landed after this PR pass it's presubmits. I have a fix in process of landing here: #173731 (review)

…

On Wed, Aug 13, 2025, 5:12 p.m. Danny Tuppeny ***@***.***> wrote: *DanTup* left a comment (flutter/flutter#173654) <#173654 (comment)> I think because the other change (1eb2f68 <1eb2f68>) removed the import for ../runner/flutter_command_runner.dart. I thought the merge queue would've prevented this kind of issue by running the bots on each change based on the parent they'll be merged with? Does it not work that way? — Reply to this email directly, view it on GitHub <#173654 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AFYWZYHXPPNNH5J6A7VEW2D3NOS5RAVCNFSM6AAAAACDXXMEN6VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTCOBVHA2TAMJZGY> . You are receiving this because you modified the open/close state.Message ID: ***@***.***>

DanTup · 2025-08-14T09:03:17Z

I thought this was what the merge queue was intended to solve, but I found

https://github.com/flutter/flutter/blob/master/docs/infra/merge_queue.md

At this time, no additional tests will run in the merge queue. A PR that passes presubmit checks will be allowed to land on the target branch immediately.

I guess that explains why it wasn't caught, though it makes me wonder why the queue is so slow if it's not running tests 🤔

bkonyi · 2025-08-14T13:22:39Z

I thought this was what the merge queue was intended to solve, but I found

https://github.com/flutter/flutter/blob/master/docs/infra/merge_queue.md

At this time, no additional tests will run in the merge queue. A PR that passes presubmit checks will be allowed to land on the target branch immediately.

I guess that explains why it wasn't caught, though it makes me wonder why the queue is so slow if it's not running tests 🤔

We definitely run some checks... I think? @jtmcdole, is the merge queue documentation up to date?

…3654)

flutter/flutter@34c2a3b...f4334d2 2025-08-14 [email protected] Roll Dart SDK from 9b4691f35139 to 214a7f829913 (2 revisions) (flutter/flutter#173769) 2025-08-14 [email protected] Roll Skia from b3e86773dae1 to dca5f05fee87 (4 revisions) (flutter/flutter#173763) 2025-08-14 [email protected] Roll Dart SDK from 73153bdc1459 to 9b4691f35139 (3 revisions) (flutter/flutter#173755) 2025-08-14 [email protected] Roll Skia from 5852eddfd404 to b3e86773dae1 (1 revision) (flutter/flutter#173750) 2025-08-14 [email protected] Allow empty initial time when using text input mode in showTimePicker dialog (flutter/flutter#172847) 2025-08-13 [email protected] Roll Skia from 525e2bf80559 to 5852eddfd404 (2 revisions) (flutter/flutter#173740) 2025-08-13 [email protected] [web] Popping a nameless route should preserve the correct route name (flutter/flutter#173652) 2025-08-13 [email protected] Make sure that a ChoiceChip doesn't crash in 0x0 environment (flutter/flutter#173322) 2025-08-13 [email protected] [ Tool ] Fix missing import for widget_preview.dart (flutter/flutter#173731) 2025-08-13 [email protected] Roll Skia from f7fdda3cd0e6 to 525e2bf80559 (7 revisions) (flutter/flutter#173727) 2025-08-13 [email protected] Do not include `:unittests` unless `enable_unittests` (flutter/flutter#173729) 2025-08-13 [email protected] Roll Packages from 08a9b2c to 6cb9113 (1 revision) (flutter/flutter#173726) 2025-08-13 [email protected] fix: selected date decorator renders outside PageView in `DatePickerDialog` dialog (flutter/flutter#171718) 2025-08-13 [email protected] [ Widget Preview ] Add `--machine` mode (flutter/flutter#173654) 2025-08-13 [email protected] Make sure that a Chip doesn't crash in 0x0 environment (flutter/flutter#173245) 2025-08-13 [email protected] feat: Cupertino sheet implement upward stretch on full sheet (flutter/flutter#168547) 2025-08-13 [email protected] Fix visual overlap of transparent routes barrier when using FadeForwardsPageTransitionsBuilder (flutter/flutter#167032) 2025-08-13 [email protected] Fix `ChipThemeData` lerp for `BorderSide` (flutter/flutter#173160) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected],[email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

Currently only outputs a single event with information about where the widget preview environment is served from: `[{"event":"widget_preview.started","params":{"url":"http://localhost:61383"}}]` Fixes flutter#173545

…r#9807) flutter/flutter@34c2a3b...f4334d2 2025-08-14 [email protected] Roll Dart SDK from 9b4691f35139 to 214a7f829913 (2 revisions) (flutter/flutter#173769) 2025-08-14 [email protected] Roll Skia from b3e86773dae1 to dca5f05fee87 (4 revisions) (flutter/flutter#173763) 2025-08-14 [email protected] Roll Dart SDK from 73153bdc1459 to 9b4691f35139 (3 revisions) (flutter/flutter#173755) 2025-08-14 [email protected] Roll Skia from 5852eddfd404 to b3e86773dae1 (1 revision) (flutter/flutter#173750) 2025-08-14 [email protected] Allow empty initial time when using text input mode in showTimePicker dialog (flutter/flutter#172847) 2025-08-13 [email protected] Roll Skia from 525e2bf80559 to 5852eddfd404 (2 revisions) (flutter/flutter#173740) 2025-08-13 [email protected] [web] Popping a nameless route should preserve the correct route name (flutter/flutter#173652) 2025-08-13 [email protected] Make sure that a ChoiceChip doesn't crash in 0x0 environment (flutter/flutter#173322) 2025-08-13 [email protected] [ Tool ] Fix missing import for widget_preview.dart (flutter/flutter#173731) 2025-08-13 [email protected] Roll Skia from f7fdda3cd0e6 to 525e2bf80559 (7 revisions) (flutter/flutter#173727) 2025-08-13 [email protected] Do not include `:unittests` unless `enable_unittests` (flutter/flutter#173729) 2025-08-13 [email protected] Roll Packages from 08a9b2c to 6cb9113 (1 revision) (flutter/flutter#173726) 2025-08-13 [email protected] fix: selected date decorator renders outside PageView in `DatePickerDialog` dialog (flutter/flutter#171718) 2025-08-13 [email protected] [ Widget Preview ] Add `--machine` mode (flutter/flutter#173654) 2025-08-13 [email protected] Make sure that a Chip doesn't crash in 0x0 environment (flutter/flutter#173245) 2025-08-13 [email protected] feat: Cupertino sheet implement upward stretch on full sheet (flutter/flutter#168547) 2025-08-13 [email protected] Fix visual overlap of transparent routes barrier when using FadeForwardsPageTransitionsBuilder (flutter/flutter#167032) 2025-08-13 [email protected] Fix `ChipThemeData` lerp for `BorderSide` (flutter/flutter#173160) If this roll has caused a breakage, revert this CL and stop the roller using the controls here: https://autoroll.skia.org/r/flutter-packages Please CC [email protected],[email protected] on the revert to ensure that a human is aware of the problem. To file a bug in Packages: https://github.com/flutter/flutter/issues/new/choose To report a problem with the AutoRoller itself, please file a bug: https://issues.skia.org/issues/new?component=1389291&template=1850622 Documentation for the AutoRoller is here: https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

Currently only outputs a single event with information about where the widget preview environment is served from: `[{"event":"widget_preview.started","params":{"url":"http://localhost:61383"}}]` Fixes flutter#173545

…3654)

Currently only outputs a single event with information about where the widget preview environment is served from: `[{"event":"widget_preview.started","params":{"url":"http://localhost:61383"}}]` Fixes flutter#173545

github-actions bot added the tool Affects the "flutter" command-line tool. See also t: labels. label Aug 12, 2025

bkonyi requested review from DanTup and jyameo August 12, 2025 21:30

gemini-code-assist bot reviewed Aug 12, 2025

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bkonyi added 2 commits August 12, 2025 17:33

Update tests

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bkonyi added the autosubmit Merge PR when tree becomes green via auto submit App label Aug 13, 2025

DanTup mentioned this pull request Aug 13, 2025

Ship an (experimental) integration of the Flutter Widget Preview Dart-Code/Dart-Code#5649

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Roll Flutter from 34c2a3b158b2 to c932faf75472 (17 revisions) flutter/packages#9806

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Roll Flutter from 34c2a3b158b2 to f4334d27934b (18 revisions) flutter/packages#9807

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