throw more specific toolexit when git fails during upgrade (#57162)

packages/flutter_tools/lib/src/commands/upgrade.dart

@@ -219,12 +219,23 @@ class UpgradeCommandRunner {
           workingDirectory: workingDirectory,
       );
       revision = result.stdout.trim();
-    } on Exception {
+    } on Exception catch (e) {
+      final String errorString = e.toString();
+      if (errorString.contains('fatal: HEAD does not point to a branch')) {
         throwToolExit(
-        'Unable to upgrade Flutter: no origin repository configured. '
-        "Run 'git remote add origin "
-        "https://github.com/flutter/flutter' in $workingDirectory",
+          'You are not currently on a release branch. Use git to '
+          'check out an official branch (\'stable\', \'beta\', \'dev\', or \'master\') '
+          'and retry, for example:\n'
+          '  git checkout stable'
         );
+      } else if (errorString.contains('fatal: no upstream configured for branch')) {
+        throwToolExit(
+          'Unable to upgrade Flutter: no origin repository configured. '
+          'Run \'git remote add origin '
+          'https://github.com/flutter/flutter\' in $workingDirectory');
+      } else {
+        throwToolExit(errorString);
+      }
     }
     return revision;
   }

packages/flutter_tools/test/commands.shard/permeable/upgrade_test.dart

@@ -160,7 +160,7 @@ void main() {
       Platform: () => fakePlatform,
     });
 
-    testUsingContext('fetchRemoteRevision', () async {
+    testUsingContext('fetchRemoteRevision returns revision if git succeeds', () async {
       const String revision = 'abc123';
       when(processManager.run(
         <String>['git', 'fetch', '--tags'],
@@ -185,6 +185,60 @@ void main() {
       Platform: () => fakePlatform,
     });
 
+    testUsingContext('fetchRemoteRevision throws toolExit if HEAD is detached', () async {
+      when(processManager.run(
+        <String>['git', 'fetch', '--tags'],
+        environment:anyNamed('environment'),
+        workingDirectory: anyNamed('workingDirectory')),
+      ).thenAnswer((Invocation invocation) async {
+        return FakeProcessResult()..exitCode = 0;
+      });
+      when(processManager.run(
+        <String>['git', 'rev-parse', '--verify', '@{u}'],
+        environment:anyNamed('environment'),
+        workingDirectory: anyNamed('workingDirectory')),
+      ).thenThrow(const ProcessException(
+        'git',
+        <String>['rev-parse', '--verify', '@{u}'],
+        'fatal: HEAD does not point to a branch',
+      ));
+      expect(
+        () async => await realCommandRunner.fetchRemoteRevision(),
+        throwsToolExit(message: 'You are not currently on a release branch.'),
+      );
+    }, overrides: <Type, Generator>{
+      ProcessManager: () => processManager,
+      Platform: () => fakePlatform,
+    });
+
+    testUsingContext('fetchRemoteRevision throws toolExit if no upstream configured', () async {
+      when(processManager.run(
+        <String>['git', 'fetch', '--tags'],
+        environment:anyNamed('environment'),
+        workingDirectory: anyNamed('workingDirectory')),
+      ).thenAnswer((Invocation invocation) async {
+        return FakeProcessResult()..exitCode = 0;
+      });
+      when(processManager.run(
+        <String>['git', 'rev-parse', '--verify', '@{u}'],
+        environment:anyNamed('environment'),
+        workingDirectory: anyNamed('workingDirectory')),
+      ).thenThrow(const ProcessException(
+        'git',
+        <String>['rev-parse', '--verify', '@{u}'],
+        'fatal: no upstream configured for branch',
+      ));
+      expect(
+        () async => await realCommandRunner.fetchRemoteRevision(),
+        throwsToolExit(
+          message: 'Unable to upgrade Flutter: no origin repository configured\.',
+        ),
+      );
+    }, overrides: <Type, Generator>{
+      ProcessManager: () => processManager,
+      Platform: () => fakePlatform,
+    });
+
     testUsingContext('git exception during attemptReset throwsToolExit', () async {
       const String revision = 'abc123';
       const String errorMessage = 'fatal: Could not parse object ´$revision´';