Add changelog updater

pkgs/repo_manage/lib/changelog_updater.dart

@@ -0,0 +1,93 @@
+// Copyright (c) 2026, the Dart project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'dart:convert';
+import 'dart:io';
+
+import 'src/common.dart';
+
+String updateChangelogContent(String changelog, String message) {
+  final lines = LineSplitter.split(changelog).toList();
+  var currentVersion = '0.0.1';
+  var currentVersionLine = 0;
+
+  for (var i = 0; i < lines.length; i++) {
+    final line = lines[i].trim();
+    if (line.startsWith('## ')) {
+      final content = line.substring(3).trim();
+      final version = content.split(' ').first;
+      if (version.startsWith(RegExp(r'\d'))) {
+        currentVersion = version;
+        currentVersionLine = i;
+        break;
+      }
+    }
+  }
+
+  final isWip = currentVersion.endsWith('-wip');
+
+  final output = <String>[];
+  if (isWip) {
+    var sectionEnd = lines.indexWhere(
+            (line) => line.startsWith('## '), currentVersionLine + 1) -
+        1;
+    if (sectionEnd < 0) {
+      sectionEnd = lines.length;
+    }
+
+    output.addAll(lines.take(sectionEnd));
+    output.add('- $message');
+    output.addAll(lines.skip(sectionEnd));
+  } else {
+    output.addAll([
+      '## $currentVersion-wip',
+      '',
+      '- $message',
+      '',
+      ...lines,
+    ]);
+  }
+
+  return '${output.join('\n')}\n';
+}
+
+class ChangelogUpdaterCommand extends ReportCommand {
+  ChangelogUpdaterCommand()
+      : super('changelog', 'Update a changelog with a new entry.') {
+    argParser.addOption(
+      'changelog',
+      abbr: 'c',
+      help: 'Path to the changelog file to update. Defaults to CHANGELOG.md.',
+    );
+  }
+
+  @override
+  Future<int> run() async {
+    final args = argResults?.rest ?? const <String>[];
+    if (args.isEmpty) {
+      stderr.writeln('''
+Usage: dart run report.dart changelog [--changelog <path>] "Your changelog message"''');
+      stderr
+          .writeln('If no --changelog path is provided, CHANGELOG.md is used.');
+      return 1;
+    }
+
+    final message = args.join(' ');
+    final changelogFile =
+        File(argResults?['changelog'] as String? ?? 'CHANGELOG.md');
+
+    if (!changelogFile.existsSync()) {
+      stderr.writeln('Error: ${changelogFile.path} not found.');
+      return 1;
+    }
+
+    final newChangelog = updateChangelogContent(
+      changelogFile.readAsStringSync(),
+      message,
+    );
+    changelogFile.writeAsStringSync(newChangelog);
+    stdout.writeln('Changelog updated successfully.');
+    return 0;
+  }
+}

pkgs/repo_manage/lib/src/common.dart

@@ -10,6 +10,7 @@ import 'package:github/github.dart';
 import 'package:graphql/client.dart';
 
 import '../branches.dart';
+import '../changelog_updater.dart';
 import '../contributors.dart';
 import '../issue_transfer.dart';
 import '../labels.dart';
@@ -80,6 +81,7 @@ class ReportCommandRunner extends CommandRunner<int> {
       : super('report',
             'Run various reports on Dart and Flutter related repositories.') {
     addCommand(BranchesCommand());
+    addCommand(ChangelogUpdaterCommand());
     addCommand(ContributorsCommand());
     addCommand(LabelsCommand());
     addCommand(LabelsUpdateCommand());

pkgs/repo_manage/pubspec.yaml

@@ -3,6 +3,10 @@ description: Miscellaneous issue, repo, and PR query tools.
 
 publish_to: none
 
+executables:
+  report:
+
+
 environment:
   sdk: ^3.3.0
 
@@ -15,3 +19,4 @@ dependencies:
 
 dev_dependencies:
   dart_flutter_team_lints: ^3.0.0
+  test: ^1.25.0

pkgs/repo_manage/test/changelog_updater_test.dart

@@ -0,0 +1,66 @@
+import 'dart:io';
+
+import 'package:repo_manage/changelog_updater.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('updateChangelogContent', () {
+    test('adds an entry to a wip changelog', () {
+      expectGolden(
+        inputPath: 'test/data/changelog_wip.md',
+        goldenPath: 'test/data/golden/changelog_wip.golden',
+        message: 'Add new feature',
+      );
+    });
+
+    test('creates a new wip section from a released changelog', () {
+      expectGolden(
+        inputPath: 'test/data/changelog_release.md',
+        goldenPath: 'test/data/golden/changelog_release.golden',
+        message: 'Fix regression',
+      );
+    });
+
+    test('creates a starter changelog when none is present', () {
+      expectGolden(
+        inputPath: 'test/data/changelog_empty.md',
+        goldenPath: 'test/data/golden/changelog_empty.golden',
+        message: 'Initial entry',
+      );
+    });
+
+    test('handles complex timezone formatting', () {
+      expectGolden(
+        inputPath: 'test/data/changelog_complex_timezone.md',
+        goldenPath: 'test/data/golden/changelog_complex_timezone.golden',
+        message: 'Add new feature',
+      );
+    });
+
+    test('handles complex timezone formatting with WIP suffix', () {
+      expectGolden(
+        inputPath: 'test/data/changelog_complex_timezone_wip.md',
+        goldenPath: 'test/data/golden/changelog_complex_timezone_wip.golden',
+        message: 'Add new feature',
+      );
+    });
+  });
+}
+
+void expectGolden({
+  required String inputPath,
+  required String goldenPath,
+  required String message,
+}) {
+  final input = File(inputPath).readAsStringSync();
+  final output = updateChangelogContent(input, message);
+  final goldenFile = File(goldenPath);
+
+  if (!goldenFile.existsSync()) {
+    goldenFile.parent.createSync(recursive: true);
+    goldenFile.writeAsStringSync(output);
+    return;
+  }
+
+  expect(output, goldenFile.readAsStringSync());
+}