Catch and display version check errors during doctor (#44868)

packages/flutter_tools/lib/src/base/user_messages.dart

@@ -10,7 +10,7 @@ UserMessages get userMessages => context.get<UserMessages>();
 class UserMessages {
   // Messages used in FlutterValidator
   String flutterStatusInfo(String channel, String version, String os, String locale) =>
-      'Channel $channel, v$version, on $os, locale $locale';
+      'Channel ${channel ?? 'unknown'}, v${version ?? 'Unknown'}, on $os, locale $locale';
   String flutterVersion(String version, String flutterRoot) =>
       'Flutter version $version at $flutterRoot';
   String flutterRevision(String revision, String age, String date) =>

packages/flutter_tools/lib/src/doctor.dart

@@ -587,13 +587,22 @@ class FlutterValidator extends DoctorValidator {
   Future<ValidationResult> validate() async {
     final List<ValidationMessage> messages = <ValidationMessage>[];
     ValidationType valid = ValidationType.installed;
+    String versionChannel;
+    String frameworkVersion;
 
-    final FlutterVersion version = FlutterVersion.instance;
+    try {
+      final FlutterVersion version = FlutterVersion.instance;
+      versionChannel = version.channel;
+      frameworkVersion = version.frameworkVersion;
+      messages.add(ValidationMessage(userMessages.flutterVersion(frameworkVersion, Cache.flutterRoot)));
+      messages.add(ValidationMessage(userMessages.flutterRevision(version.frameworkRevisionShort, version.frameworkAge, version.frameworkDate)));
+      messages.add(ValidationMessage(userMessages.engineRevision(version.engineRevisionShort)));
+      messages.add(ValidationMessage(userMessages.dartRevision(version.dartSdkVersion)));
+    } on VersionCheckError catch (e) {
+      messages.add(ValidationMessage.error(e.message));
+      valid = ValidationType.partial;
+    }
 
-    messages.add(ValidationMessage(userMessages.flutterVersion(version.frameworkVersion, Cache.flutterRoot)));
-    messages.add(ValidationMessage(userMessages.flutterRevision(version.frameworkRevisionShort, version.frameworkAge, version.frameworkDate)));
-    messages.add(ValidationMessage(userMessages.engineRevision(version.engineRevisionShort)));
-    messages.add(ValidationMessage(userMessages.dartRevision(version.dartSdkVersion)));
     final String genSnapshotPath =
       artifacts.getArtifactPath(Artifact.genSnapshot);
 
@@ -609,7 +618,7 @@ class FlutterValidator extends DoctorValidator {
     }
 
     return ValidationResult(valid, messages,
-      statusInfo: userMessages.flutterStatusInfo(version.channel, version.frameworkVersion, os.name, platform.localeName),
+      statusInfo: userMessages.flutterStatusInfo(versionChannel, frameworkVersion, os.name, platform.localeName),
     );
   }
 }

packages/flutter_tools/test/commands.shard/hermetic/doctor_test.dart

@@ -20,6 +20,7 @@ import 'package:flutter_tools/src/reporting/reporting.dart';
 import 'package:flutter_tools/src/vscode/vscode.dart';
 import 'package:flutter_tools/src/vscode/vscode_validator.dart';
 import 'package:flutter_tools/src/web/workflow.dart';
+import 'package:flutter_tools/src/version.dart';
 import 'package:mockito/mockito.dart';
 import 'package:process/process.dart';
 import 'package:quiver/testing/async.dart';
@@ -35,9 +36,11 @@ final Map<Type, Generator> noColorTerminalOverride = <Type, Generator>{
 
 void main() {
   MockProcessManager mockProcessManager;
+  MockFlutterVersion mockFlutterVersion;
 
   setUp(() {
     mockProcessManager = MockProcessManager();
+    mockFlutterVersion = MockFlutterVersion();
   });
 
   group('doctor', () {
@@ -507,6 +510,34 @@ void main() {
       ProcessManager: () => mockProcessManager,
       Platform: _kNoColorOutputPlatform,
     });
+
+    testUsingContext('version checking does not work', () async {
+      final VersionCheckError versionCheckError = VersionCheckError('version error');
+
+      when(mockFlutterVersion.channel).thenReturn('unknown');
+      when(mockFlutterVersion.frameworkVersion).thenReturn('0.0.0');
+      when(mockFlutterVersion.frameworkDate).thenThrow(versionCheckError);
+
+      when(mockProcessManager.runSync(
+        <String>[artifacts.getArtifactPath(Artifact.genSnapshot)],
+        workingDirectory: anyNamed('workingDirectory'),
+        environment: anyNamed('environment'),
+      )).thenReturn(ProcessResult(101, 255, '', ''));
+
+      expect(await FlutterValidatorDoctor().diagnose(verbose: false), isTrue);
+
+      expect(testLogger.statusText, equals(
+        'Doctor summary (to see all details, run flutter doctor -v):\n'
+          '[!] Flutter (Channel unknown, v0.0.0, on fake OS name and version, locale en-US)\n'
+          '    ✗ version error\n\n'
+          '! Doctor found issues in 1 category.\n'
+      ));
+    }, overrides: <Type, Generator>{
+      OutputPreferences: () => OutputPreferences(wrapText: false),
+      ProcessManager: () => mockProcessManager,
+      Platform: _kNoColorOutputPlatform,
+      FlutterVersion: () => mockFlutterVersion,
+    });
   });
 
   testUsingContext('validate non-verbose output wrapping', () async {
@@ -1018,3 +1049,4 @@ class VsCodeValidatorTestTargets extends VsCodeValidator {
 }
 
 class MockProcessManager extends Mock implements ProcessManager {}
+class MockFlutterVersion extends Mock implements FlutterVersion {}