[tool] Add initial file-based command skipping (#8928)

Adds initial file-based filtering. This does not attempt to be comprehensive, just to get some low-hanging fruit, and to create a blueprint for anyone to follow in the future when adding more filtering. I expect that once this is in place, what will happen is that as we notice cases where PRs are hitting slow or flaky tests that they clearly don't need to, we can incrementally improve the filtering on demand.

Fixes flutter/flutter#136394

Author: stuartmorgan-g

script/tool/lib/src/analyze_command.dart

@@ -6,6 +6,7 @@ import 'dart:io' as io;
 
 import 'package:file/file.dart';
 
+import 'common/file_filters.dart';
 import 'common/output_utils.dart';
 import 'common/package_looping_command.dart';
 import 'common/repository_package.dart';
@@ -92,6 +93,13 @@ class AnalyzeCommand extends PackageLoopingCommand {
     return false;
   }
 
+  @override
+  bool shouldIgnoreFile(String path) {
+    return isRepoLevelNonCodeImpactingFile(path) ||
+        isNativeCodeFile(path) ||
+        isPackageSupportFile(path);
+  }
+
   @override
   Future<void> initializeRun() async {
     _allowedCustomAnalysisDirectories = getYamlListArg(_customAnalysisFlag);

script/tool/lib/src/build_examples_command.dart

@@ -6,6 +6,7 @@ import 'package:file/file.dart';
 import 'package:yaml/yaml.dart';
 
 import 'common/core.dart';
+import 'common/file_filters.dart';
 import 'common/output_utils.dart';
 import 'common/package_looping_command.dart';
 import 'common/plugin_utils.dart';
@@ -134,6 +135,11 @@ class BuildExamplesCommand extends PackageLoopingCommand {
     return getNullableBoolArg(_swiftPackageManagerFlag);
   }
 
+  @override
+  bool shouldIgnoreFile(String path) {
+    return isRepoLevelNonCodeImpactingFile(path) || isPackageSupportFile(path);
+  }
+
   @override
   Future<void> initializeRun() async {
     final List<String> platformFlags = _platforms.keys.toList();

script/tool/lib/src/common/file_filters.dart

@@ -0,0 +1,53 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/// Returns true for repository-level paths of files that do not affect *any*
+/// code-related commands (example builds, Dart analysis, native code analysis,
+/// native tests, Dart tests, etc.) for use in command-ignored-files lists for
+/// commands that are only affected by package code.
+bool isRepoLevelNonCodeImpactingFile(String path) {
+  return <String>[
+    'AUTHORS',
+    'CODEOWNERS',
+    'CONTRIBUTING.md',
+    'LICENSE',
+    'README.md',
+    // This deliberate lists specific files rather than excluding the whole
+    // .github directory since it's better to have false negatives than to
+    // accidentally skip tests if something is later added to the directory
+    // that could affect packages.
+    '.github/PULL_REQUEST_TEMPLATE.md',
+    '.github/dependabot.yml',
+    '.github/labeler.yml',
+    '.github/post_merge_labeler.yml',
+    '.github/workflows/pull_request_label.yml',
+  ].contains(path);
+}
+
+/// Returns true for native (non-Dart) code files, for use in command-ignored-
+/// files lists for commands that aren't affected by native code (e.g., Dart
+/// analysis and unit tests).
+bool isNativeCodeFile(String path) {
+  return path.endsWith('.c') ||
+      path.endsWith('.cc') ||
+      path.endsWith('.cpp') ||
+      path.endsWith('.h') ||
+      path.endsWith('.m') ||
+      path.endsWith('.swift') ||
+      path.endsWith('.java') ||
+      path.endsWith('.kt');
+}
+
+/// Returns true for package-level human-focused support files, for use in
+/// command-ignored-files lists for commands that aren't affected by files that
+/// aren't used in any builds.
+///
+/// This must *not* include metadata files that do affect builds, such as
+/// pubspec.yaml.
+bool isPackageSupportFile(String path) {
+  return path.endsWith('/AUTHORS') ||
+      path.endsWith('/CHANGELOG.md') ||
+      path.endsWith('/CONTRIBUTING.md') ||
+      path.endsWith('/README.md');
+}

script/tool/lib/src/common/package_looping_command.dart

@@ -109,6 +109,20 @@ abstract class PackageLoopingCommand extends PackageCommand {
   /// The package currently being run by [runForPackage].
   PackageEnumerationEntry? _currentPackageEntry;
 
+  /// When running against a merge base, this is called before [initializeRun]
+  /// for every changed file, to see if that file is a file that is guaranteed
+  /// *not* to require running this command.
+  ///
+  /// If every changed file returns true, then the command will be skipped.
+  /// Because this causes tests not to run, subclasses should be very
+  /// consevative about what returns true; for anything borderline it is much
+  /// better to err on the side of running tests unnecessarily than to risk
+  /// losing test coverage.
+  ///
+  /// [path] is a POSIX-style path regardless of the host platforrm, and is
+  /// relative to the git repo root.
+  bool shouldIgnoreFile(String path) => false;
+
   /// Called during [run] before any calls to [runForPackage]. This provides an
   /// opportunity to fail early if the command can't be run (e.g., because the
   /// arguments are invalid), and to set up any run-level state.
@@ -281,6 +295,14 @@ abstract class PackageLoopingCommand extends PackageCommand {
     baseSha = await gitVersionFinder.getBaseSha();
     changedFiles = await gitVersionFinder.getChangedFiles();
 
+    // Check whether the command needs to run.
+    if (changedFiles.isNotEmpty && changedFiles.every(shouldIgnoreFile)) {
+      _printColorized(
+          'SKIPPING ALL PACKAGES: No changed files affect this command',
+          Styles.DARK_GRAY);
+      return true;
+    }
+
     await initializeRun();
 
     final List<PackageEnumerationEntry> targetPackages =

script/tool/lib/src/dart_test_command.dart

@@ -5,6 +5,7 @@
 import 'package:file/file.dart';
 
 import 'common/core.dart';
+import 'common/file_filters.dart';
 import 'common/output_utils.dart';
 import 'common/package_looping_command.dart';
 import 'common/plugin_utils.dart';
@@ -65,6 +66,13 @@ class DartTestCommand extends PackageLoopingCommand {
   PackageLoopingType get packageLoopingType =>
       PackageLoopingType.includeAllSubpackages;
 
+  @override
+  bool shouldIgnoreFile(String path) {
+    return isRepoLevelNonCodeImpactingFile(path) ||
+        isNativeCodeFile(path) ||
+        isPackageSupportFile(path);
+  }
+
   @override
   Future<PackageResult> runForPackage(RepositoryPackage package) async {
     if (!package.testDirectory.existsSync()) {

script/tool/lib/src/drive_examples_command.dart

@@ -9,6 +9,7 @@ import 'dart:io';
 import 'package:file/file.dart';
 
 import 'common/core.dart';
+import 'common/file_filters.dart';
 import 'common/output_utils.dart';
 import 'common/package_looping_command.dart';
 import 'common/plugin_utils.dart';
@@ -68,6 +69,11 @@ class DriveExamplesCommand extends PackageLoopingCommand {
 
   Map<String, List<String>> _targetDeviceFlags = const <String, List<String>>{};
 
+  @override
+  bool shouldIgnoreFile(String path) {
+    return isRepoLevelNonCodeImpactingFile(path) || isPackageSupportFile(path);
+  }
+
   @override
   Future<void> initializeRun() async {
     final List<String> platformSwitches = <String>[

script/tool/lib/src/firebase_test_lab_command.dart

@@ -8,6 +8,7 @@ import 'package:file/file.dart';
 import 'package:uuid/uuid.dart';
 
 import 'common/core.dart';
+import 'common/file_filters.dart';
 import 'common/flutter_command_utils.dart';
 import 'common/gradle.dart';
 import 'common/output_utils.dart';
@@ -122,6 +123,11 @@ class FirebaseTestLabCommand extends PackageLoopingCommand {
     _firebaseProjectConfigured = true;
   }
 
+  @override
+  bool shouldIgnoreFile(String path) {
+    return isRepoLevelNonCodeImpactingFile(path) || isPackageSupportFile(path);
+  }
+
   @override
   Future<PackageResult> runForPackage(RepositoryPackage package) async {
     final List<PackageResult> results = <PackageResult>[];

script/tool/lib/src/lint_android_command.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'common/core.dart';
+import 'common/file_filters.dart';
 import 'common/flutter_command_utils.dart';
 import 'common/gradle.dart';
 import 'common/output_utils.dart';
@@ -29,6 +30,15 @@ class LintAndroidCommand extends PackageLoopingCommand {
   final String description = 'Runs "gradlew lint" on Android plugins.\n\n'
       'Requires the examples to have been build at least once before running.';
 
+  @override
+  bool shouldIgnoreFile(String path) {
+    return isRepoLevelNonCodeImpactingFile(path) ||
+        isPackageSupportFile(path) ||
+        // These are part of the build, but don't affect native code analysis.
+        path.endsWith('/pubspec.yaml') ||
+        path.endsWith('.dart');
+  }
+
   @override
   Future<PackageResult> runForPackage(RepositoryPackage package) async {
     if (!pluginSupportsPlatform(platformAndroid, package,

script/tool/lib/src/native_test_command.dart

@@ -9,6 +9,7 @@ import 'package:meta/meta.dart';
 
 import 'common/cmake.dart';
 import 'common/core.dart';
+import 'common/file_filters.dart';
 import 'common/flutter_command_utils.dart';
 import 'common/gradle.dart';
 import 'common/output_utils.dart';
@@ -114,6 +115,13 @@ this command.
 
   Set<String> _xcodeWarningsExceptions = <String>{};
 
+  @override
+  bool shouldIgnoreFile(String path) {
+    return isRepoLevelNonCodeImpactingFile(path) || isPackageSupportFile(path);
+    // It may seem tempting to filter out *.dart, but that would skip critical
+    // testing since native integration tests run the full compiled application.
+  }
+
   @override
   Future<void> initializeRun() async {
     _platforms = <String, _PlatformDetails>{

script/tool/lib/src/xcode_analyze_command.dart

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 import 'common/core.dart';
+import 'common/file_filters.dart';
 import 'common/flutter_command_utils.dart';
 import 'common/output_utils.dart';
 import 'common/package_looping_command.dart';
@@ -47,6 +48,15 @@ class XcodeAnalyzeCommand extends PackageLoopingCommand {
   final String description =
       'Runs Xcode analysis on the iOS and/or macOS example apps.';
 
+  @override
+  bool shouldIgnoreFile(String path) {
+    return isRepoLevelNonCodeImpactingFile(path) ||
+        isPackageSupportFile(path) ||
+        // These are part of the build, but don't affect native code analysis.
+        path.endsWith('/pubspec.yaml') ||
+        path.endsWith('.dart');
+  }
+
   @override
   Future<void> initializeRun() async {
     if (!(getBoolArg(platformIOS) || getBoolArg(platformMacOS))) {