--experimental-faster-testing cannot resolve the project's own package: URIs — regression in #169556

Steps to reproduce

On a path containing no hyphens (so #161083 is not also in play):

flutter create --project-name sample --platforms=macos sample
cd sample
rm test/widget_test.dart

echo 'const int answer = 42;' > lib/foo.dart

cat > test/one_test.dart <<'EOF'
import 'package:flutter_test/flutter_test.dart';
import 'package:sample/foo.dart';

void main() {
  test('one', () => expect(answer, 42));
}
EOF

cat > test/two_test.dart <<'EOF'
import 'package:flutter_test/flutter_test.dart';

void main() {
  test('two', () => expect(2 + 2, 4));
}
EOF

flutter pub get
flutter test test/one_test.dart test/two_test.dart                              # passes
flutter test --experimental-faster-testing test/one_test.dart test/two_test.dart # fails

Two test files are needed because the flag is ignored for a single file. one_test.dart must import the project's own package by package: URI — that is what triggers this. (--platforms is incidental; only lib/ and test/ matter.)

Expected results

Both commands pass.

Actual results

Plain flutter test passes (+2: All tests passed!). With --experimental-faster-testing:

test/one_test.dart:2:8: Error: Error when reading '../../lib/foo.dart': No such file or directory
import 'package:sample/foo.dart';
       ^
test/one_test.dart:5:28: Error: Undefined name 'answer'.
  test('one', () => expect(answer, 42));
                           ^^^^^^
00:00 +1 -1: Some tests failed.
Failing tests:
  test/one_test.dart: one

Exit code 1. two_test.dart, which imports nothing from the project, still passes — only the file with the package: self-import fails. The import is a package URI, but it is reported as a missing relative path pointing outside the project.

Root cause

packages/flutter_tools/lib/src/test/runner.dart, in _generateIsolateSpawningTesterPackageConfig:

projectPackageConfig = PackageConfig.parseBytes(
  packageConfigFile.readAsBytesSync(),
  Uri.file(flutterProject.directory.path),   // base URI
);

PackageConfig.parseBytes resolves relative URIs against baseUri; its dartdoc says the base "can be the URI of that file, or of the directory it occurs in" — the package_config.json itself, or .dart_tool/. It is given the project directory instead, one level above .dart_tool/, and via Uri.file without a trailing slash, so the last segment is stripped as if it were a filename.

The generated project's root package entry is:

{"name": "sample", "rootUri": "../", "packageUri": "lib/", "languageVersion": "3.12"}

Resolving "rootUri": "../" against the wrong base therefore lands two levels too high:

/private/lib/foo.dart, printed by the CFE relative to the CWD, is exactly the reported ../../lib/foo.dart.

The two adjacent parseBytes call sites in the same file already pass a file URI — only the project's own config is given a directory path:

runner.dart:214,216  Uri.file(flutterProject.directory.path)        <-- this bug
runner.dart:238,240  flutterToolsPackageConfigFile.uri              <-- correct
runner.dart:633,635  isolateSpawningTesterPackageConfigFile.uri     <-- correct

This is a regression

Introduced by #169556 ("Workspace", merged 2025-06-03):

  packages/flutter_tools/lib/src/test/runner.dart
- projectPackageConfigFile.uri,
+ Uri.file(flutterProject.directory.path),

Restoring packageConfigFile.uri as the base resolves it.

Reachability

This sits behind path sanitization. On 3.44.x, pathToImport uses a chained .replaceAll('.', '_').replaceAll(':', '_').replaceAll('/', '_') (runner.dart:277-282), so hyphenated paths fail earlier with invalid Dart identifiers (#161083) and never reach this. From 3.45.0-0.1.pre, pathToImport sanitizes with .replaceAll(RegExp(r'[^a-zA-Z0-9]'), '_') (runner.dart:283), so hyphenated paths now get through and hit this instead.

Relationship to existing issues

• Distinct from --experimental-faster-testing doesn't sanitize paths #161083 (path sanitization) — the bug that currently hides this one.
• Distinct from flutter test: (includes patch) experimental faster testing - support for paths with '-' character and also workspaces #168657 — its patch predates this regression (3.29.2 still passed projectPackageConfigFile.uri) and targets workspace lookup, not the base URI.

Versions

Reproduced with the steps above on:

• 3.44.6 stable (ee80f08bbf, Dart 3.12.2) — base URI at runner.dart:216
• 3.47.0-0.4.pre beta (034409942b, 2026-08-04) — base URI at runner.dart:219

Also present in 3.44.4 (runner.dart:216) and unchanged on master as of 2026-08-07.

Flutter doctor

[✓] Flutter (Channel stable, 3.44.6, on macOS 26.6.1 25G76 darwin-arm64, locale en-US) [208ms]
    • Flutter version 3.44.6 on channel stable at /Users/USER/fvm/versions/3.44.6
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision ee80f08bbf (4 weeks ago), 2026-07-08 15:02:06 -0700
    • Engine revision 83675ed276
    • Dart version 3.12.2
    • DevTools version 2.57.0
    • Feature flags: enable-web, enable-linux-desktop, enable-macos-desktop, enable-windows-desktop, enable-android, enable-ios, cli-animations, enable-native-assets, no-enable-swift-package-manager, omit-legacy-version-file, enable-lldb-debugging, enable-uiscene-migration

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    • Android SDK at /Users/USER/Library/Android/sdk
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    • Platform android-36.1, build-tools 35.0.1
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      This JDK is specified in your Flutter configuration.
      To change the current JDK, run: `flutter config --jdk-dir="path/to/jdk"`.
    • Java version OpenJDK Runtime Environment Homebrew (build 17.0.20+0)
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[✓] Xcode - develop for iOS and macOS (Xcode 26.6) [459ms]
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 17F113
    • CocoaPods version 1.17.0

[✓] Chrome - develop for the web [5ms]
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Connected device (4 available) [5.8s]
    • <device> • <redacted> • ios            • iOS 26.5.2 23F84
    • <device> • <redacted> • ios            • iOS 26.6 23G71
    • macOS (desktop)                     • macos                     • darwin-arm64   • macOS 26.6.1 25G76 darwin-arm64
    • Chrome (web)                        • chrome                    • web-javascript • Google Chrome 151.0.7922.109
    ! Error: Browsing on the local area network for <device>. Ensure the device is unlocked and attached with a cable or associated with the same local area network as this Mac.
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[✓] Network resources [407ms]
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