During golden test image comparison 2 lists of a different type are compared with the method "identical", so this will never be true. The test image is a _Uint8ArrayView while the master image is an Uint8List. So that results in always a heavy computation to get the difference between the test and the master image.
When you run this test snippet I go from 51 seconds to 14 seconds:
```dart
import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';
void main() {
for (int i = 0; i < 100; i++) {
testWidgets('Small test', (WidgetTester tester) async {
await tester.pumpWidget(Directionality(textDirection: TextDirection.ltr, child: Text('jo')));
await expectLater(find.byType(Text), matchesGoldenFile('main.png'));
});
}
}
```
Update the `matchesGoldenFile()` / `LocalComparisonOutput` code to generate failure images for golden tests that fail when the image sizes do not match. This can make it far quicker to identify what is wrong with the test image.
Fixes https://github.com/flutter/flutter/issues/141488
- [ x I read and followed the [Flutter Style Guide], including [Features we expect every widget to implement].
* Update project.pbxproj files to say Flutter rather than Chromium
Also, the templates now have an empty organization so that we don't cause people to give their apps a Flutter copyright.
* Update the copyright notice checker to require a standard notice on all files
* Update copyrights on Dart files. (This was a mechanical commit.)
* Fix weird license headers on Dart files that deviate from our conventions; relicense Shrine.
Some were already marked "The Flutter Authors", not clear why. Their
dates have been normalized. Some were missing the blank line after the
license. Some were randomly different in trivial ways for no apparent
reason (e.g. missing the trailing period).
* Clean up the copyrights in non-Dart files. (Manual edits.)
Also, make sure templates don't have copyrights.
* Fix some more ORGANIZATIONNAMEs
* Fixing LocalFileComparator output
* Fixing path separators for windows failures
* Windows path issues
* Testing
* ++
* ++
* Fixing base directory - windows
* Clean up
* Upgrade everything except matcher.
* Roll matcher (and test)
* Adjust tests that depend on flutter:test directly to depend on a shim
* Require use of package:test shim and remove other references to package:test
This will allow external tools that wrap our test harness to share the
code that generates the test bootstrap.
This change exposed an issue whereby the LocalGoldenFileComparator
was being too strict in its URI handling, so this changes relaxes
that constraint as well (and adds associated tests).
In order to avoid checking binaries into flutter/flutter,
this comparator can be used to retrieve golden files from
a sibling flutter/goldens repository.
https://github.com/flutter/flutter/issues/16859
* Add a `matchesGoldenFile()` async matcher that will match
a finder's widget's rasterized image against a golden file.
* Add support for pluggable image comparison backends
* Add a default backend that does simplistic PNG byte
comparison on locally stored golden files.
* Add support for `flutter test --update-goldens`, which will
treat the rasterized image bytes produced during the test
as the new golden bytes and update the golden file accordingly
Still TODO:
* Add support for the `flutter_test_config.dart` test config hook
* Utilize `flutter_test_config.dart` in `packages/flutter/test`
to install a backend that retrieves golden files from a dedicated
`flutter/goldens` repo
https://github.com/flutter/flutter/issues/16859
