ci: Dynamically fetch Flutter versions for the CI test matrix instead…

.github/workflows/main.yml

@@ -7,12 +7,24 @@ on:
     branches: [ master ]
 
 jobs:
+  setup_flutter_versions:
+    runs-on: ubuntu-latest
+    outputs:
+      flutter-versions: ${{ steps.id_flutter_versions.outputs.versions }}
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dart-lang/setup-dart@v1
+      - name: Fetch Flutter versions
+        id: id_flutter_versions
+        run: dart tool/fetch_versions.dart >> $GITHUB_OUTPUT
+
   test_flutter_versions:
+    needs: setup_flutter_versions
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
-        flutter: [ '3.24.0', '3.27.0', '3.29.0', '3.32.0', '3.35.0', 'stable', 'beta' ]
+        flutter: ${{ fromJson(needs.setup_flutter_versions.outputs.flutter-versions) }}
     name: Tests on Flutter ${{ matrix.flutter }}
     steps:
       - uses: actions/checkout@v4

test/fetch_versions_test.dart

@@ -0,0 +1,80 @@
+import 'package:flutter_test/flutter_test.dart';
+import '../tool/fetch_versions.dart';
+
+void main() {
+  test(
+      'parseVersions extracts last 5 minor versions, skips 1st, returns 4 + stable/beta',
+      () {
+    final json = {
+      "releases": [
+        // Minor 3.38
+        {
+          "version": "3.38.5",
+          "channel": "stable",
+          "release_date": "2025-12-12T10:00:00Z"
+        },
+        {
+          "version": "3.38.4",
+          "channel": "stable",
+          "release_date": "2025-12-11T10:00:00Z"
+        },
+
+        // Minor 3.35
+        {
+          "version": "3.35.7",
+          "channel": "stable",
+          "release_date": "2025-11-12T10:00:00Z"
+        },
+
+        // Minor 3.32
+        {
+          "version": "3.32.8",
+          "channel": "stable",
+          "release_date": "2025-10-12T10:00:00Z"
+        },
+
+        // Minor 3.29
+        {
+          "version": "3.29.3",
+          "channel": "stable",
+          "release_date": "2025-09-12T10:00:00Z"
+        },
+
+        // Minor 3.27
+        {
+          "version": "3.27.4",
+          "channel": "stable",
+          "release_date": "2025-08-12T10:00:00Z"
+        },
+
+        // Minor 3.24
+        {
+          "version": "3.24.2",
+          "channel": "stable",
+          "release_date": "2025-07-12T10:00:00Z"
+        },
+
+        // Beta (ignored by filter, but 'beta' string is added manually)
+        {
+          "version": "3.40.0-beta",
+          "channel": "beta",
+          "release_date": "2025-12-13T10:00:00Z"
+        },
+      ]
+    };
+
+    final versions = parseVersions(json);
+
+    expect(versions, [
+      // "3.38.5", // Skipped
+      "3.35.7",
+      "3.32.8",
+      "3.29.3",
+      "3.27.4",
+      // "3.24.2", // Removed
+      "stable",
+      "beta"
+    ]);
+    expect(versions.length, 6);
+  });
+}

tool/fetch_versions.dart

@@ -0,0 +1,77 @@
+import 'dart:convert';
+import 'dart:io';
+
+Future<void> main() async {
+  try {
+    final json = await _fetchJson();
+    final versions = parseVersions(json);
+    print('versions=${jsonEncode(versions)}');
+  } catch (e) {
+    stderr.writeln('Error: $e');
+    exit(1);
+  }
+}
+
+Future<Map<String, dynamic>> _fetchJson() async {
+  final url = Uri.parse(
+      'https://storage.googleapis.com/flutter_infra_release/releases/releases_linux.json');
+  final httpClient = HttpClient();
+  try {
+    final request = await httpClient.getUrl(url);
+    final response = await request.close();
+    if (response.statusCode != 200) {
+      throw HttpException('Failed to fetch releases: ${response.statusCode}');
+    }
+    final responseBody = await response.transform(utf8.decoder).join();
+    return jsonDecode(responseBody) as Map<String, dynamic>;
+  } finally {
+    httpClient.close();
+  }
+}
+
+List<String> parseVersions(Map<String, dynamic> json) {
+  final releases = (json['releases'] as List).cast<Map<String, dynamic>>();
+
+  // Filter for stable channel
+  final stableReleases = releases.where((r) => r['channel'] == 'stable');
+
+  // Group by Major.Minor (e.g. 3.38)
+  final Map<String, Map<String, dynamic>> latestByMinor = {};
+
+  for (final release in stableReleases) {
+    final version = release['version'] as String;
+    final parts = version.split('.');
+    if (parts.length < 2) continue;
+    final minor = '${parts[0]}.${parts[1]}';
+
+    final releaseDate = DateTime.parse(release['release_date']);
+
+    if (!latestByMinor.containsKey(minor)) {
+      latestByMinor[minor] = release;
+    } else {
+      final currentBest = latestByMinor[minor]!;
+      final currentBestDate = DateTime.parse(currentBest['release_date']);
+      // Keep the most recent patch
+      if (releaseDate.isAfter(currentBestDate)) {
+        latestByMinor[minor] = release;
+      }
+    }
+  }
+
+  // Sort groups by release date descending
+  final sortedByDate = latestByMinor.values.toList()
+    ..sort((a, b) {
+      final dateA = DateTime.parse(a['release_date']);
+      final dateB = DateTime.parse(b['release_date']);
+      return dateB.compareTo(dateA);
+    });
+
+  // Take the last 5 minor versions
+  final top5 = sortedByDate.take(5).map((r) => r['version'] as String).toList();
+
+  // Skip the first one (latest stable) to avoid duplication with 'stable' channel
+  // Return the next 4
+  final historicVersions = top5.skip(1).toList();
+
+  return [...historicVersions, 'stable', 'beta'];
+}