Do not retry if pub get is run in offline mode (#90394)

packages/flutter_tools/lib/src/dart/pub.dart

@@ -27,6 +27,10 @@ const String _kPubEnvironmentKey = 'PUB_ENVIRONMENT';
 /// The console environment key used by the pub tool to find the cache directory.
 const String _kPubCacheEnvironmentKey = 'PUB_CACHE';
 
+/// The UNAVAILABLE exit code returned by the pub tool.
+/// (see https://github.com/dart-lang/pub/blob/master/lib/src/exit_codes.dart)
+const int _kPubExitCodeUnavailable = 69;
+
 typedef MessageFilter = String Function(String message);
 
 /// Represents Flutter-specific data that is added to the `PUB_ENVIRONMENT`
@@ -250,7 +254,7 @@ class _DefaultPub implements Pub {
         context: context,
         directory: directory,
         failureMessage: 'pub $command failed',
-        retry: true,
+        retry: !offline,
         flutterRootOverride: flutterRootOverride,
       );
       status.stop();
@@ -303,7 +307,7 @@ class _DefaultPub implements Pub {
     int attempts = 0;
     int duration = 1;
     int code;
-    loop: while (true) {
+    while (true) {
       attempts += 1;
       code = await _processUtils.stream(
         _pubCommand(arguments),
@@ -311,15 +315,15 @@ class _DefaultPub implements Pub {
         mapFunction: filterWrapper, // may set versionSolvingFailed, lastPubMessage
         environment: await _createPubEnvironment(context, flutterRootOverride),
       );
-      String message;
-      switch (code) {
-        case 69: // UNAVAILABLE in https://github.com/dart-lang/pub/blob/master/lib/src/exit_codes.dart
+      String? message;
+      if (retry) {
+        if (code == _kPubExitCodeUnavailable) {
           message = 'server unavailable';
-          break;
-        default:
-          break loop;
+        }
+      }
+      if (message == null) {
+        break;
       }
-      assert(message != null);
       versionSolvingFailed = false;
       _logger.printStatus(
         '$failureMessage ($message) -- attempting retry $attempts in $duration '

packages/flutter_tools/test/general.shard/dart/pub_get_test.dart

@@ -594,6 +594,54 @@ void main() {
     expect(processManager, hasNoRemainingExpectations);
   });
 
+  testWithoutContext('pub get offline does not retry', () async {
+    String? error;
+
+    const FakeCommand pubGetCommand = FakeCommand(
+      command: <String>[
+          'bin/cache/dart-sdk/bin/dart',
+          '__deprecated_pub',
+          '--verbosity=warning',
+          'get',
+          '--no-precompile',
+          '--offline',
+      ],
+      exitCode: 69,
+      environment: <String, String>{'FLUTTER_ROOT': '', 'PUB_ENVIRONMENT': 'flutter_cli:flutter_tests'},
+    );
+    final FakeProcessManager processManager = FakeProcessManager.list(<FakeCommand>[
+      pubGetCommand,
+    ]);
+    final BufferLogger logger = BufferLogger.test();
+    final FileSystem fileSystem = MemoryFileSystem.test();
+    final Pub pub = Pub(
+      fileSystem: fileSystem,
+      logger: logger,
+      processManager: processManager,
+      usage: TestUsage(),
+      platform: FakePlatform(
+        environment: const <String, String>{},
+      ),
+      botDetector: const BotDetectorAlwaysNo(),
+    );
+
+    FakeAsync().run((FakeAsync time) {
+      expect(logger.statusText, '');
+      pub.get(context: PubContext.flutterTests, offline: true).then((void value) {
+        error = 'test completed unexpectedly';
+      }, onError: (dynamic thrownError) {
+        error = 'test failed unexpectedly: $thrownError';
+      });
+      time.elapse(const Duration(milliseconds: 500));
+      expect(logger.statusText,
+        'Running "flutter pub get" in /...\n'
+      );
+    });
+    expect(logger.errorText, isEmpty);
+    expect(error, 'test failed unexpectedly: Exception: pub get failed (69; no message)');
+    expect(processManager, hasNoRemainingExpectations);
+  });
+
   testWithoutContext('pub get 66 shows message from pub', () async {
     final BufferLogger logger = BufferLogger.test();
     final FileSystem fileSystem = MemoryFileSystem.test();