Ensure release notes show most recent notes for pre-release version

packages/devtools_app/lib/src/framework/about_dialog.dart

@@ -38,7 +38,8 @@ class DevToolsAboutDialog extends StatelessWidget {
                   'release notes',
                   style: theme.linkTextStyle,
                 ),
-                onTap: () => releaseNotesController.toggleVisibility(true),
+                onTap: () =>
+                    unawaited(releaseNotesController.openLatestReleaseNotes()),
               ),
             ],
           ),

packages/devtools_app/lib/src/framework/release_notes/release_notes.dart

@@ -15,7 +15,10 @@ import '../../shared/side_panel.dart';
 
 final _log = Logger('release_notes');
 
-const debugTestReleaseNotes = false;
+// This is not const because it is manipulated for testing as well as for
+// local development.
+bool debugTestReleaseNotes = false;
+const debugUseStagedFlutterWebsite = false;
 const releaseNotesKey = Key('release_notes');
 
 class ReleaseNotesViewer extends SidePanelViewer {
@@ -37,17 +40,17 @@ class ReleaseNotesController extends SidePanelController {
 
   static const _unsupportedPathSyntax = '{{site.url}}';
 
-  String get _flutterDocsSite => debugTestReleaseNotes
+  String get _flutterDocsSite => debugUseStagedFlutterWebsite
       ? 'https://flutter-website-dt-staging.web.app'
       : 'https://docs.flutter.dev';
 
   void _init() {
     if (debugTestReleaseNotes || server.isDevToolsServerAvailable) {
-      _maybeFetchReleaseNotes();
+      _maybeShowReleaseNotes();
     }
   }
 
-  void _maybeFetchReleaseNotes() async {
+  void _maybeShowReleaseNotes() async {
     SemanticVersion previousVersion = SemanticVersion();
     if (server.isDevToolsServerAvailable) {
       final lastReleaseNotesShownVersion =
@@ -56,63 +59,102 @@ class ReleaseNotesController extends SidePanelController {
         previousVersion = SemanticVersion.parse(lastReleaseNotesShownVersion);
       }
     }
+    await _fetchAndShowReleaseNotes(
+      versionFloor: debugTestReleaseNotes ? null : previousVersion,
+    );
+  }
+
+  /// Fetches and shows the most recent release notes for the current DevTools
+  /// version, decreasing the patch version by 1 each time until we find release
+  /// notes or until we hit [versionFloor].
+  Future<void> _fetchAndShowReleaseNotes({
+    SemanticVersion? versionFloor,
+  }) async {
+    versionFloor ??= SemanticVersion();
+
     // Parse the current version instead of using [devtools.version] directly to
     // strip off any build metadata (any characters following a '+' character).
     // Release notes will be hosted on the Flutter website with a version number
     // that does not contain any build metadata.
-    final parsedCurrentVersion = SemanticVersion.parse(devtools.version);
-    final parsedCurrentVersionStr = parsedCurrentVersion.toString();
-    if (parsedCurrentVersion > previousVersion) {
-      try {
-        await _fetchReleaseNotes(parsedCurrentVersion);
-      } catch (e) {
-        // Fail gracefully if we cannot find release notes for the current
-        // version of DevTools.
-        markdownText = null;
-        toggleVisibility(false);
-        _log.warning(
-          'Warning: could not find release notes for DevTools version '
-          '$parsedCurrentVersionStr. $e',
-        );
+    final parsedVersion = SemanticVersion.parse(devtools.version);
+    var notesVersion = latestVersionToCheckForReleaseNotes(parsedVersion);
+    try {
+      // Try all patch versions for this major.minor combination until we find
+      // release notes (e.g. 2.11.4 -> 2.11.3 -> 2.11.2 -> ...).
+      final attemptedVersions = <String>[];
+      var attempts = notesVersion.patch;
+      while (attempts >= 0 && notesVersion > versionFloor) {
+        final versionString = notesVersion.toString();
+        try {
+          String releaseNotesMarkdown = await http.read(
+            Uri.parse(_releaseNotesUrl(versionString)),
+          );
+          // This is a workaround so that the images in release notes will appear.
+          // The {{site.url}} syntax is best practices for the flutter website
+          // repo, where these release notes are hosted, so we are performing this
+          // workaround on our end to ensure the images render properly.
+          releaseNotesMarkdown = releaseNotesMarkdown.replaceAll(
+            _unsupportedPathSyntax,
+            _flutterDocsSite,
+          );
+
+          markdown.value = releaseNotesMarkdown;
+          toggleVisibility(true);
+          if (server.isDevToolsServerAvailable) {
+            unawaited(
+              server.setLastShownReleaseNotesVersion(versionString),
+            );
+          }
+          return;
+        } catch (e) {
+          attempts--;
+          attemptedVersions.add(versionString);
+          if (attempts < 0) {
+            // ignore: avoid-throw-in-catch-block, false positive
+            throw Exception(
+              'Could not find release notes for DevTools versions '
+              '${attemptedVersions.join(', ')}.'
+              '\n$e',
+            );
+          }
+          notesVersion = notesVersion.downgrade(downgradePatch: true);
+        }
       }
+    } catch (e) {
+      // Fail gracefully if we cannot find release notes for the current
+      // version of DevTools.
+      markdown.value = null;
+      toggleVisibility(false);
+      _log.warning('Warning: $e');
     }
   }
 
-  Future<void> _fetchReleaseNotes(SemanticVersion version) async {
-    final currentVersionString = version.toString();
-
-    // Try all patch versions for this major.minor combination until we find
-    // release notes (e.g. 2.11.4 -> 2.11.3 -> 2.11.2 -> ...).
-    var attempts = version.patch;
-    while (attempts >= 0) {
-      final versionString = version.toString();
-      try {
-        String releaseNotesMarkdown = await http.read(
-          Uri.parse(_releaseNotesUrl(versionString)),
-        );
-        // This is a workaround so that the images in release notes will appear.
-        // The {{site.url}} syntax is best practices for the flutter website
-        // repo, where these release notes are hosted, so we are performing this
-        // workaround on our end to ensure the images render properly.
-        releaseNotesMarkdown = releaseNotesMarkdown.replaceAll(
-          _unsupportedPathSyntax,
-          _flutterDocsSite,
-        );
+  @visibleForTesting
+  SemanticVersion latestVersionToCheckForReleaseNotes(
+    SemanticVersion currentVersion,
+  ) {
+    // If the current version is a pre-release, downgrade the minor to find the
+    // previous DevTools release, and start looking for release notes from this
+    // value. Release notes will never be published for pre-release versions.
+    if (currentVersion.isPreRelease) {
+      // It is very unlikely the patch value of the DevTools version will ever
+      // be above this number. This is a safe number to start looking for
+      // release notes at.
+      const safeStartPatch = 10;
+      currentVersion = SemanticVersion(
+        major: currentVersion.major,
+        minor: currentVersion.minor - 1,
+        patch: safeStartPatch,
+      );
+    }
+    return currentVersion;
+  }
 
-        markdownText = releaseNotesMarkdown;
-        toggleVisibility(true);
-        unawaited(
-          server.setLastShownReleaseNotesVersion(currentVersionString),
-        );
-        return;
-      } catch (_) {
-        attempts--;
-        if (attempts < 0) {
-          rethrow;
-        }
-        version = version.downgrade(downgradePatch: true);
-      }
+  Future<void> openLatestReleaseNotes() async {
+    if (markdown.value == null) {
+      await _fetchAndShowReleaseNotes();
     }
+    toggleVisibility(true);
   }
 
   String _releaseNotesUrl(String currentVersion) {

packages/devtools_app/lib/src/shared/side_panel.dart

@@ -194,9 +194,7 @@ class SidePanel extends AnimatedWidget {
 }
 
 class SidePanelController {
-  ValueListenable<String?> get markdown => _markdown;
-
-  final _markdown = ValueNotifier<String?>(null);
+  final markdown = ValueNotifier<String?>(null);
 
   ValueListenable<bool> get isVisible => _isVisible;
 
@@ -205,8 +203,4 @@ class SidePanelController {
   void toggleVisibility(bool visible) {
     _isVisible.value = visible;
   }
-
-  set markdownText(String? markdownText) {
-    _markdown.value = markdownText;
-  }
 }

packages/devtools_app/release_notes/README.md

@@ -1,13 +1,13 @@
 ## Generating Release notes
-- Release notes for DevTools are hosted on the flutter website (see [archive](https://docs.flutter.dev/development/tools/devtools/release-notes)).
+- Release notes for DevTools are hosted on the flutter website (see [archive](https://docs.flutter.dev/tools/devtools/release-notes)).
 - To add release notes for the latest release, create a PR with the appropriate changes for your release.
     - The [NEXT_RELEASE_NOTES.md](NEXT_RELEASE_NOTES.md) file contains the running release notes for the current version.
     - see example [PR](https://github.com/flutter/website/pull/6791) for an idea of how to add those to the Flutter website.
     - NOTE: when adding images, be cognizant that the images will be rendered in a relatively small window in DevTools, and should be sized accordingly.
 - Test these changes locally before creating the PR.
     - See [README.md](https://github.com/flutter/website/blob/main/README.md)
 for getting setup to run the Flutter website locally.
-    - Release notes can be found at [http://localhost:4002/development/tools/devtools/release-notes/](http://localhost:4002/development/tools/devtools/release-notes/)
+    - Release notes can be found at [http://localhost:4002/development/tools/devtools/release-notes/](http://localhost:4002/tools/devtools/release-notes/)
 
 - Once you are satisfied with the release notes
     - stage the Flutter website on Firebase
@@ -47,7 +47,7 @@ for getting setup to run the Flutter website locally.
     ```
 
 ### Testing the release notes in DevTools
-- In `release_notes.dart` flip the `debugTestReleaseNotes` flag to true.
+- In `release_notes.dart` flip the `debugTestReleaseNotes` and `debugUseStagedFlutterWebsite` flags to true.
 
 - from the main `devtools/` directory, run the following:
     ```shell
@@ -64,4 +64,3 @@ Serving DevTools at http://127.0.0.1:57336.
 
 - Visit the DevTools link
 - verify the release notes viewer displays the new release notes as expected.
-

packages/devtools_app/test/shared/release_notes_test.dart

@@ -0,0 +1,29 @@
+// Copyright 2023 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:devtools_app/devtools_app.dart';
+import 'package:devtools_shared/devtools_shared.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  group('$ReleaseNotesController', () {
+    late ReleaseNotesController controller;
+    setUp(() {
+      debugTestReleaseNotes = true;
+      controller = ReleaseNotesController();
+    });
+
+    test('latestVersionToCheckForReleaseNotes', () {
+      var version = controller.latestVersionToCheckForReleaseNotes(
+        SemanticVersion.parse('2.24.5-dev.1'),
+      );
+      expect(version.toString(), '2.23.10');
+
+      version = controller.latestVersionToCheckForReleaseNotes(
+        SemanticVersion.parse('2.24.1'),
+      );
+      expect(version.toString(), '2.24.1');
+    });
+  });
+}