Fix prepare_package.dart not updating base_url (#81941)

dev/bots/prepare_package.dart

@@ -577,7 +577,8 @@ class ArchivePublisher {
   /// This method will throw if the target archive already exists on cloud
   /// storage.
   Future<void> publishArchive([bool forceUpload = false]) async {
-    for (final String releaseFolder in <String>[oldGsReleaseFolder, newGsReleaseFolder]) {
+    for (final bool isNew in <bool>[false, true]) {
+      final String releaseFolder = isNew ? newGsReleaseFolder : oldGsReleaseFolder;
       final String destGsPath = '$releaseFolder/$destinationArchivePath';
       if (!forceUpload) {
         if (await _cloudPathExists(destGsPath) && !dryRun) {
@@ -591,7 +592,7 @@ class ArchivePublisher {
         dest: destGsPath,
       );
       assert(tempDir.existsSync());
-      await _updateMetadata('$releaseFolder/${getMetadataFilename(platform)}', newBucket: false);
+      await _updateMetadata('$releaseFolder/${getMetadataFilename(platform)}', newBucket: isNew);
     }
   }
 

dev/bots/test/prepare_package_test.dart

@@ -409,6 +409,88 @@ void main() {
         expect(contents, equals(encoder.convert(jsonData)));
       });
 
+      test('updates base_url from old bucket to new bucket', () async {
+        final String archivePath = path.join(tempDir.absolute.path, archiveName);
+        final String jsonPath = path.join(tempDir.absolute.path, releasesName);
+        final String gsJsonPath = 'gs://flutter_infra/releases/$releasesName';
+        final String newGsJsonPath = 'gs://flutter_infra_release/releases/$releasesName';
+        final String releasesJson = '''
+{
+  "base_url": "https://storage.googleapis.com/flutter_infra/releases",
+  "current_release": {
+    "beta": "3ea4d06340a97a1e9d7cae97567c64e0569dcaa2",
+    "dev": "5a58b36e36b8d7aace89d3950e6deb307956a6a0"
+  },
+  "releases": [
+    {
+      "hash": "5a58b36e36b8d7aace89d3950e6deb307956a6a0",
+      "channel": "dev",
+      "version": "v0.2.3",
+      "release_date": "2018-03-20T01:47:02.851729Z",
+      "archive": "dev/$platformName/flutter_${platformName}_v0.2.3-dev.zip",
+      "sha256": "4fe85a822093e81cb5a66c7fc263f68de39b5797b294191b6d75e7afcc86aff8"
+    },
+    {
+      "hash": "b9bd51cc36b706215915711e580851901faebb40",
+      "channel": "beta",
+      "version": "v0.2.2",
+      "release_date": "2018-03-16T18:48:13.375013Z",
+      "archive": "dev/$platformName/flutter_${platformName}_v0.2.2-dev.zip",
+      "sha256": "6073331168cdb37a4637a5dc073d6a7ef4e466321effa2c529fa27d2253a4d4b"
+    },
+    {
+      "hash": "$testRef",
+      "channel": "stable",
+      "version": "v0.0.0",
+      "release_date": "2018-03-20T01:47:02.851729Z",
+      "archive": "stable/$platformName/flutter_${platformName}_v0.0.0-dev.zip",
+      "sha256": "5dd34873b3a3e214a32fd30c2c319a0f46e608afb72f0d450b2d621a6d02aebd"
+    }
+  ]
+}
+''';
+        File(jsonPath).writeAsStringSync(releasesJson);
+        File(archivePath).writeAsStringSync('archive contents');
+        final Map<String, List<ProcessResult>> calls = <String, List<ProcessResult>>{
+          // This process fails because the file does NOT already exist
+          '$gsutilCall -- stat $gsArchivePath': <ProcessResult>[ProcessResult(0, 1, '', '')],
+          '$gsutilCall -- rm $gsArchivePath': null,
+          '$gsutilCall -- -h Content-Type:$archiveMime cp $archivePath $gsArchivePath': null,
+          '$gsutilCall -- cp $gsJsonPath $jsonPath': null,
+          '$gsutilCall -- rm $gsJsonPath': null,
+          '$gsutilCall -- -h Content-Type:application/json -h Cache-Control:max-age=60 cp $jsonPath $gsJsonPath': null,
+          '$gsutilCall -- stat $newGsArchivePath': <ProcessResult>[ProcessResult(0, 1, '', '')],
+          '$gsutilCall -- rm $newGsArchivePath': null,
+          '$gsutilCall -- -h Content-Type:$archiveMime cp $archivePath $newGsArchivePath': null,
+          '$gsutilCall -- cp $newGsJsonPath $jsonPath': null,
+          '$gsutilCall -- rm $newGsJsonPath': null,
+          '$gsutilCall -- -h Content-Type:application/json -h Cache-Control:max-age=60 cp $jsonPath $newGsJsonPath': null,
+        };
+        processManager.addCommands(convertResults(calls));
+        final File outputFile = File(path.join(tempDir.absolute.path, archiveName));
+        outputFile.createSync();
+        assert(tempDir.existsSync());
+        final ArchivePublisher publisher = ArchivePublisher(
+          tempDir,
+          testRef,
+          Branch.stable,
+          'v1.2.3',
+          outputFile,
+          false,
+          processManager: processManager,
+          subprocessOutput: false,
+          platform: platform,
+        );
+        assert(tempDir.existsSync());
+        await publisher.publishArchive();
+
+        final File releaseFile = File(jsonPath);
+        expect(releaseFile.existsSync(), isTrue);
+        final String contents = releaseFile.readAsStringSync();
+        final Map<String, dynamic> jsonData = json.decode(contents) as Map<String, dynamic>;
+        expect(jsonData['base_url'], 'https://storage.googleapis.com/flutter_infra_release/releases');
+      });
+
       test('publishArchive throws if forceUpload is false and artifact already exists on cloud storage', () async {
         final String archiveName = platform.isLinux ? 'archive.tar.xz' : 'archive.zip';
         final File outputFile = File(path.join(tempDir.absolute.path, archiveName));