Improve network resources doctor check (#120417)

...and various other minor cleanup:

* Moved "FLUTTER_STORAGE_BASE_URL" into a constant throughout the code. There are other strings that we should do that to but this one was relevant to the code I was changing.

* Fixed the logger's handling of slow warnings. Previously it deleted too much text. Fixed the test for that to actually verify it entirely, too.

* Made the logger delete the slow warning when it's finished.

* Fixed 'Please choose one (To quit, press "q/Q")' message to be the cleaner 'Please choose one (or "q" to quit)'.

* Added a debug toString to ValidationResult for debugging purposes (not used).

* In http_host_validator:

  - Shortened constant names to be clearer (e.g. kPubDevHttpHost -> kPubDev).
  - Added GitHub as a tested host since when you run `flutter` we hit that immediately.
  - Renamed the check "Network resources".
  - Updated the `slowWarning` of the check to say which hosts are pending.
  - Removed all timeout logic. Timeouts violate our style guide.
  - Removed `int.parse(... ?? '10')`; passing a constant to `int.parse` is inefficient.
  - Replaced the `_HostValidationResult` class with `String?` for simplicity.
  - Improved the error messages to be more detailed.
  - Removed all checks that dependened on the stringification of exceptions. That's very brittle.
  - Added a warning specifically for HandshakeException that talks about the implications (MITM attacks).
  - Replaced exception-message-parsing logic with just calling `Uri.tryParse` and validating the result.
  - Replaced a lot of list-filtering logic with just a single for loop to check the results.
  - Replaced code that added a constant to a known-empty list with just returning a constant list.
  - Revamped the logic for deciding which hosts to check to just use a single chain of if/else blocks instead of getters, lists literals with `if` expressions, `??`, functions, etc spread over multiple places in the code.

packages/flutter_tools/lib/src/android/gradle.dart

@@ -16,6 +16,7 @@ import '../base/deferred_component.dart';
 import '../base/file_system.dart';
 import '../base/io.dart';
 import '../base/logger.dart';
+import '../base/net.dart';
 import '../base/platform.dart';
 import '../base/process.dart';
 import '../base/terminal.dart';
@@ -696,7 +697,7 @@ void printHowToConsumeAar({
   1. Open ${fileSystem.path.join('<host>', 'app', 'build.gradle')}
   2. Ensure you have the repositories configured, otherwise add them:
 
-      String storageUrl = System.env.FLUTTER_STORAGE_BASE_URL ?: "https://storage.googleapis.com"
+      String storageUrl = System.env.$kFlutterStorageBaseUrl ?: "https://storage.googleapis.com"
       repositories {
         maven {
             url '${repoDirectory.path}'

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

@@ -1360,7 +1360,9 @@ class AnonymousSpinnerStatus extends Status {
     if (seemsSlow) {
       if (!timedOut) {
         timedOut = true;
-        _clear(_currentLineLength);
+        if (_currentLineLength > _lastAnimationFrameLength) {
+          _clear(_currentLineLength - _lastAnimationFrameLength);
+        }
       }
       if (_slowWarning == '' && slowWarningCallback != null) {
         _slowWarning = slowWarningCallback!();
@@ -1398,7 +1400,8 @@ class AnonymousSpinnerStatus extends Status {
     assert(timer!.isActive);
     timer?.cancel();
     timer = null;
-    _clear(_lastAnimationFrameLength);
+    _clear(_lastAnimationFrameLength + _slowWarning.length);
+    _slowWarning = '';
     _lastAnimationFrameLength = 0;
     super.finish();
   }

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

@@ -14,6 +14,7 @@ import 'logger.dart';
 import 'platform.dart';
 
 const int kNetworkProblemExitCode = 50;
+const String kFlutterStorageBaseUrl = 'FLUTTER_STORAGE_BASE_URL';
 
 typedef HttpClientFactory = HttpClient Function();
 
@@ -106,15 +107,16 @@ class Net {
       }
       response = await request.close();
     } on ArgumentError catch (error) {
-      final String? overrideUrl = _platform.environment['FLUTTER_STORAGE_BASE_URL'];
+      final String? overrideUrl = _platform.environment[kFlutterStorageBaseUrl];
       if (overrideUrl != null && url.toString().contains(overrideUrl)) {
         _logger.printError(error.toString());
         throwToolExit(
-          'The value of FLUTTER_STORAGE_BASE_URL ($overrideUrl) could not be '
+          'The value of $kFlutterStorageBaseUrl ($overrideUrl) could not be '
           'parsed as a valid url. Please see https://flutter.dev/community/china '
           'for an example of how to use it.\n'
           'Full URL: $url',
-          exitCode: kNetworkProblemExitCode,);
+          exitCode: kNetworkProblemExitCode,
+        );
       }
       _logger.printError(error.toString());
       rethrow;

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

@@ -274,7 +274,7 @@ class UserMessages {
       'Found $count devices with name or id matching $deviceId:';
   String get flutterMultipleDevicesFound => 'Multiple devices found:';
   String flutterChooseDevice(int option, String name, String deviceId) => '[$option]: $name ($deviceId)';
-  String get flutterChooseOne => 'Please choose one (To quit, press "q/Q")';
+  String get flutterChooseOne => 'Please choose one (or "q" to quit)';
   String get flutterSpecifyDeviceWithAllOption =>
       'More than one device connected; please specify a device with '
       "the '-d <deviceId>' flag, or use '-d all' to act on all devices.";

packages/flutter_tools/lib/src/cache.dart

@@ -107,8 +107,8 @@ class DevelopmentArtifact {
 ///
 /// To enable Flutter users in these environments, the Flutter tool supports
 /// custom artifact mirrors that the administrators of such environments may
-/// provide. To use an artifact mirror, the user defines the
-/// `FLUTTER_STORAGE_BASE_URL` environment variable that points to the mirror.
+/// provide. To use an artifact mirror, the user defines the [kFlutterStorageBaseUrl]
+/// (`FLUTTER_STORAGE_BASE_URL`) environment variable that points to the mirror.
 /// Flutter tool reads this variable and uses it instead of the default URLs.
 ///
 /// For more details on specific URLs used to download artifacts, see
@@ -450,15 +450,15 @@ class Cache {
   /// during the installation of the Flutter SDK.
   ///
   /// By default the base URL is https://storage.googleapis.com. However, if
-  /// `FLUTTER_STORAGE_BASE_URL` environment variable is provided, the
-  /// environment variable value is returned instead.
+  /// `FLUTTER_STORAGE_BASE_URL` environment variable ([kFlutterStorageBaseUrl])
+  /// is provided, the environment variable value is returned instead.
   ///
   /// See also:
   ///
   ///  * [cipdBaseUrl], which determines how CIPD artifacts are fetched.
   ///  * [Cache] class-level dartdocs that explain how artifact mirrors work.
   String get storageBaseUrl {
-    final String? overrideUrl = _platform.environment['FLUTTER_STORAGE_BASE_URL'];
+    final String? overrideUrl = _platform.environment[kFlutterStorageBaseUrl];
     if (overrideUrl == null) {
       return 'https://storage.googleapis.com';
     }
@@ -466,7 +466,7 @@ class Cache {
     try {
       Uri.parse(overrideUrl);
     } on FormatException catch (err) {
-      throwToolExit('"FLUTTER_STORAGE_BASE_URL" contains an invalid URI:\n$err');
+      throwToolExit('"$kFlutterStorageBaseUrl" contains an invalid URL:\n$err');
     }
     _maybeWarnAboutStorageOverride(overrideUrl);
     return overrideUrl;
@@ -479,8 +479,8 @@ class Cache {
   /// from [storageBaseUrl].
   ///
   /// By default the base URL is https://chrome-infra-packages.appspot.com/dl.
-  /// However, if `FLUTTER_STORAGE_BASE_URL` environment variable is provided,
-  /// then the following value is used:
+  /// However, if `FLUTTER_STORAGE_BASE_URL` environment variable is provided
+  /// ([kFlutterStorageBaseUrl]), then the following value is used:
   ///
   ///     FLUTTER_STORAGE_BASE_URL/flutter_infra_release/cipd
   ///
@@ -492,7 +492,7 @@ class Cache {
   ///    which contains information about CIPD.
   ///  * [Cache] class-level dartdocs that explain how artifact mirrors work.
   String get cipdBaseUrl {
-    final String? overrideUrl = _platform.environment['FLUTTER_STORAGE_BASE_URL'];
+    final String? overrideUrl = _platform.environment[kFlutterStorageBaseUrl];
     if (overrideUrl == null) {
       return 'https://chrome-infra-packages.appspot.com/dl';
     }
@@ -501,7 +501,7 @@ class Cache {
     try {
       original = Uri.parse(overrideUrl);
     } on FormatException catch (err) {
-      throwToolExit('"FLUTTER_STORAGE_BASE_URL" contains an invalid URI:\n$err');
+      throwToolExit('"$kFlutterStorageBaseUrl" contains an invalid URL:\n$err');
     }
 
     final String cipdOverride = original.replace(
@@ -1065,11 +1065,11 @@ class ArtifactUpdater {
         }
         continue;
       } on ArgumentError catch (error) {
-        final String? overrideUrl = _platform.environment['FLUTTER_STORAGE_BASE_URL'];
+        final String? overrideUrl = _platform.environment[kFlutterStorageBaseUrl];
         if (overrideUrl != null && url.toString().contains(overrideUrl)) {
           _logger.printError(error.toString());
           throwToolExit(
-            'The value of FLUTTER_STORAGE_BASE_URL ($overrideUrl) could not be '
+            'The value of $kFlutterStorageBaseUrl ($overrideUrl) could not be '
             'parsed as a valid url. Please see https://flutter.dev/community/china '
             'for an example of how to use it.\n'
             'Full URL: $url',

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

@@ -136,7 +136,7 @@ class UpdatePackagesCommand extends FlutterCommand {
   );
 
   Future<void> _downloadCoverageData() async {
-    final String urlBase = globals.platform.environment['FLUTTER_STORAGE_BASE_URL'] ?? 'https://storage.googleapis.com';
+    final String urlBase = globals.platform.environment[kFlutterStorageBaseUrl] ?? 'https://storage.googleapis.com';
     final Uri coverageUri = Uri.parse('$urlBase/flutter_infra_release/flutter/coverage/lcov.info');
     final List<int>? data = await _net.fetchUrl(
       coverageUri,

packages/flutter_tools/lib/src/doctor.dart

@@ -15,6 +15,7 @@ import 'base/context.dart';
 import 'base/file_system.dart';
 import 'base/io.dart';
 import 'base/logger.dart';
+import 'base/net.dart';
 import 'base/os.dart';
 import 'base/platform.dart';
 import 'base/terminal.dart';
@@ -528,11 +529,11 @@ class FlutterValidator extends DoctorValidator {
       messages.add(ValidationMessage(_userMessages.engineRevision(version.engineRevisionShort)));
       messages.add(ValidationMessage(_userMessages.dartRevision(version.dartSdkVersion)));
       messages.add(ValidationMessage(_userMessages.devToolsVersion(_devToolsVersion())));
-      final String? pubUrl = _platform.environment['PUB_HOSTED_URL'];
+      final String? pubUrl = _platform.environment[kPubDevOverride];
       if (pubUrl != null) {
         messages.add(ValidationMessage(_userMessages.pubMirrorURL(pubUrl)));
       }
-      final String? storageBaseUrl = _platform.environment['FLUTTER_STORAGE_BASE_URL'];
+      final String? storageBaseUrl = _platform.environment[kFlutterStorageBaseUrl];
       if (storageBaseUrl != null) {
         messages.add(ValidationMessage(_userMessages.flutterMirrorURL(storageBaseUrl)));
       }

packages/flutter_tools/lib/src/doctor_validator.dart

@@ -207,6 +207,11 @@ class ValidationResult {
         return 'partial';
     }
   }
+
+  @override
+  String toString() {
+    return '$runtimeType($type, $messages, $statusInfo)';
+  }
 }
 
 /// A status line for the flutter doctor validation to display.

packages/flutter_tools/lib/src/http_host_validator.dart

@@ -5,32 +5,20 @@
 import 'dart:async';
 
 import 'base/io.dart';
+import 'base/net.dart';
 import 'base/platform.dart';
 import 'doctor_validator.dart';
 import 'features.dart';
 
-// Overridable environment variables
-const String kEnvPubHostedUrl = 'PUB_HOSTED_URL';
-const String kEnvCloudUrl = 'FLUTTER_STORAGE_BASE_URL';
-const String kDoctorHostTimeout = 'FLUTTER_DOCTOR_HOST_TIMEOUT';
-
 /// Common Flutter HTTP hosts.
-const String kPubDevHttpHost = 'https://pub.dev/';
-const String kgCloudHttpHost = 'https://cloud.google.com/';
-
-/// MacOS specific required HTTP hosts.
-const List<String> macOSRequiredHttpHosts = <String>[
-  'https://cocoapods.org/',
-];
+const String kCloudHost = 'https://storage.googleapis.com/';
+const String kCocoaPods = 'https://cocoapods.org/';
+const String kGitHub = 'https://github.com/';
+const String kMaven = 'https://maven.google.com/';
+const String kPubDev = 'https://pub.dev/';
 
-/// Android specific required HTTP hosts.
-List<String> androidRequiredHttpHosts(Platform platform) {
-  return <String>[
-    // If kEnvCloudUrl is set, it will be used as the maven host
-    if (!platform.environment.containsKey(kEnvCloudUrl))
-      'https://maven.google.com/',
-  ];
-}
+// Overridable environment variables.
+const String kPubDevOverride = 'PUB_HOSTED_URL'; // https://dart.dev/tools/pub/environment-variables
 
 // Validator that checks all provided hosts are reachable and responsive
 class HttpHostValidator extends DoctorValidator {
@@ -41,103 +29,121 @@ class HttpHostValidator extends DoctorValidator {
   }) : _platform = platform,
       _featureFlags = featureFlags,
       _httpClient = httpClient,
-      super('HTTP Host Availability');
+      super('Network resources');
 
   final Platform _platform;
   final FeatureFlags _featureFlags;
   final HttpClient _httpClient;
 
-  @override
-  String get slowWarning => 'HTTP Host availability check is taking a long time...';
+  final Set<Uri> _activeHosts = <Uri>{};
 
-  List<String> get _requiredHosts => <String>[
-    if (_featureFlags.isMacOSEnabled) ...macOSRequiredHttpHosts,
-    if (_featureFlags.isAndroidEnabled) ...androidRequiredHttpHosts(_platform),
-    _platform.environment[kEnvPubHostedUrl] ?? kPubDevHttpHost,
-    _platform.environment[kEnvCloudUrl] ?? kgCloudHttpHost,
-  ];
+  @override
+  String get slowWarning {
+    if (_activeHosts.isEmpty) {
+      return 'Network resources check is taking a long time...';
+    }
+    return 'Attempting to reach ${_activeHosts.map((Uri url) => url.host).join(", ")}...';
+  }
 
   /// Make a head request to the HTTP host for checking availability
-  Future<_HostValidationResult> _checkHostAvailability(String host) async {
-    late final int timeout;
+  Future<String?> _checkHostAvailability(Uri host) async {
     try {
-      timeout = int.parse(_platform.environment[kDoctorHostTimeout] ?? '10');
-      final HttpClientRequest req = await _httpClient.headUrl(Uri.parse(host));
-      await req.close().timeout(Duration(seconds: timeout));
-      // HTTP host is available if no exception happened
-      return _HostValidationResult.success(host);
-    } on TimeoutException {
-      return _HostValidationResult.fail(host, 'Failed to connect to host in $timeout second${timeout == 1 ? '': 's'}');
-    } on SocketException catch (e) {
-      return _HostValidationResult.fail(host, 'An error occurred while checking the HTTP host: ${e.message}');
-    } on HttpException catch (e) {
-      return _HostValidationResult.fail(host, 'An error occurred while checking the HTTP host: ${e.message}');
-    } on HandshakeException catch (e) {
-      return _HostValidationResult.fail(host, 'An error occurred while checking the HTTP host: ${e.message}');
-    } on OSError catch (e) {
-      return _HostValidationResult.fail(host, 'An error occurred while checking the HTTP host: ${e.message}');
-    } on FormatException catch (e) {
-      if (e.message.contains('Invalid radix-10 number')) {
-        return _HostValidationResult.fail(host, 'The value of $kDoctorHostTimeout(${_platform.environment[kDoctorHostTimeout]}) is not a valid duration in seconds');
-      } else if (e.message.contains('Invalid empty scheme')){
-        // Check if the invalid host is kEnvPubHostedUrl, else it must be kEnvCloudUrl
-        final String? pubHostedUrl = _platform.environment[kEnvPubHostedUrl];
-        if (pubHostedUrl != null && host == pubHostedUrl) {
-          return _HostValidationResult.fail(host, 'The value of $kEnvPubHostedUrl(${_platform.environment[kEnvPubHostedUrl]}) could not be parsed as a valid url');
-        }
-        return _HostValidationResult.fail(host, 'The value of $kEnvCloudUrl(${_platform.environment[kEnvCloudUrl]}) could not be parsed as a valid url');
-      }
-      return _HostValidationResult.fail(host, 'An error occurred while checking the HTTP host: ${e.message}');
-    } on ArgumentError catch (e) {
-      final String exceptionMessage = e.message.toString();
-      if (exceptionMessage.contains('No host specified')) {
-        // Check if the invalid host is kEnvPubHostedUrl, else it must be kEnvCloudUrl
-        final String? pubHostedUrl = _platform.environment[kEnvPubHostedUrl];
-        if (pubHostedUrl != null && host == pubHostedUrl) {
-          return _HostValidationResult.fail(host, 'The value of $kEnvPubHostedUrl(${_platform.environment[kEnvPubHostedUrl]}) is not a valid host');
-        }
-        return _HostValidationResult.fail(host, 'The value of $kEnvCloudUrl(${_platform.environment[kEnvCloudUrl]}) is not a valid host');
-      }
-      return _HostValidationResult.fail(host, 'An error occurred while checking the HTTP host: $exceptionMessage');
+      assert(!_activeHosts.contains(host));
+      _activeHosts.add(host);
+      final HttpClientRequest req = await _httpClient.headUrl(host);
+      await req.close();
+      // HTTP host is available if no exception happened.
+      return null;
+    } on SocketException catch (error) {
+      return 'A network error occurred while checking "$host": ${error.message}';
+    } on HttpException catch (error) {
+      return 'An HTTP error occurred while checking "$host": ${error.message}';
+    } on HandshakeException catch (error) {
+      return 'A crytographic error occurred while checking "$host": ${error.message}\n'
+             'You may be experiencing a man-in-the-middle attack, your network may be '
+             'compromised, or you may have malware installed on your computer.';
+    } on OSError catch (error) {
+      return 'An error occurred while checking "$host": ${error.message}';
+    } finally {
+      _activeHosts.remove(host);
     }
   }
 
+  static Uri? _parseUrl(String value) {
+    final Uri? url = Uri.tryParse(value);
+    if (url == null || !url.hasScheme || !url.hasAuthority || (!url.hasEmptyPath && !url.hasAbsolutePath) || url.hasFragment) {
+      return null;
+    }
+    return url;
+  }
+
   @override
   Future<ValidationResult> validate() async {
-    final List<ValidationMessage> messages = <ValidationMessage>[];
-    final Iterable<Future<_HostValidationResult>> availabilityResultFutures = _requiredHosts.map(_checkHostAvailability);
-    final List<_HostValidationResult> availabilityResults = await Future.wait(availabilityResultFutures);
-
-    if (availabilityResults.every((_HostValidationResult result) => result.available)) {
-      return ValidationResult(
-          ValidationType.success,
-          messages..add(const ValidationMessage('All required HTTP hosts are available')),
-      );
+    final List<String?> availabilityResults = <String?>[];
+
+    final List<Uri> requiredHosts = <Uri>[];
+    if (_platform.environment.containsKey(kPubDevOverride)) {
+      final Uri? url = _parseUrl(_platform.environment[kPubDevOverride]!);
+      if (url == null) {
+        availabilityResults.add(
+          'Environment variable $kPubDevOverride does not specify a valid URL: "${_platform.environment[kPubDevOverride]}"\n'
+          'Please see https://flutter.dev/community/china for an example of how to use it.'
+        );
+      } else {
+        requiredHosts.add(url);
+      }
+    } else {
+      requiredHosts.add(Uri.parse(kPubDev));
     }
+    if (_platform.environment.containsKey(kFlutterStorageBaseUrl)) {
+      final Uri? url = _parseUrl(_platform.environment[kFlutterStorageBaseUrl]!);
+      if (url == null) {
+        availabilityResults.add(
+          'Environment variable $kFlutterStorageBaseUrl does not specify a valid URL: "${_platform.environment[kFlutterStorageBaseUrl]}"\n'
+          'Please see https://flutter.dev/community/china for an example of how to use it.'
+        );
+      } else {
+        requiredHosts.add(url);
+      }
+    } else {
+      requiredHosts.add(Uri.parse(kCloudHost));
+      if (_featureFlags.isAndroidEnabled) {
+        // if kFlutterStorageBaseUrl is set it is used instead of Maven
+        requiredHosts.add(Uri.parse(kMaven));
+      }
+    }
+    if (_featureFlags.isMacOSEnabled) {
+      requiredHosts.add(Uri.parse(kCocoaPods));
+    }
+    requiredHosts.add(Uri.parse(kGitHub));
 
-    availabilityResults.removeWhere((_HostValidationResult result) => result.available);
+    // Check all the hosts simultaneously.
+    availabilityResults.addAll(await Future.wait<String?>(requiredHosts.map(_checkHostAvailability)));
 
-    for (final _HostValidationResult result in availabilityResults) {
-      messages.add(ValidationMessage.error('HTTP host "${result.host}" is not reachable. Reason: ${result.failResultInfo}'));
+    int failures = 0;
+    int successes = 0;
+    final List<ValidationMessage> messages = <ValidationMessage>[];
+    for (final String? message in availabilityResults) {
+      if (message == null) {
+        successes += 1;
+      } else {
+        failures += 1;
+        messages.add(ValidationMessage.error(message));
+      }
     }
 
+    if (failures == 0) {
+      assert(successes > 0);
+      assert(messages.isEmpty);
+      return const ValidationResult(
+        ValidationType.success,
+        <ValidationMessage>[ValidationMessage('All expected network resources are available.')],
+      );
+    }
+    assert(messages.isNotEmpty);
     return ValidationResult(
-      availabilityResults.length == _requiredHosts.length
-        ? ValidationType.notAvailable
-        : ValidationType.partial,
+      successes == 0 ? ValidationType.notAvailable : ValidationType.partial,
       messages,
     );
   }
 }
-
-class _HostValidationResult {
-  _HostValidationResult.success(this.host)
-    : failResultInfo = '',
-      available = true;
-
-  _HostValidationResult.fail(this.host, this.failResultInfo) : available = false;
-
-  final String failResultInfo;
-  final String host;
-  final bool available;
-}

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

@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'dart:async';
 import 'dart:io';
 
 import 'package:flutter_tools/src/base/platform.dart';
@@ -19,7 +18,6 @@ const String kTestEnvGCloudHost = 'https://storage.flutter-io.cn';
 const Map<String, String> kTestEnvironment = <String, String>{
   'PUB_HOSTED_URL': kTestEnvPubHost,
   'FLUTTER_STORAGE_BASE_URL': kTestEnvGCloudHost,
-  'FLUTTER_DOCTOR_HOST_TIMEOUT': '1',
 };
 
 void main() {
@@ -31,7 +29,7 @@ void main() {
         final FakeHttpClient mockClient = FakeHttpClient.any();
 
         // Run the check for all operating systems one by one
-        for(final String os in osTested) {
+        for (final String os in osTested) {
           final HttpHostValidator httpHostValidator = HttpHostValidator(
             platform: FakePlatform(operatingSystem: os),
             featureFlags: TestFeatureFlags(),
@@ -48,16 +46,17 @@ void main() {
 
       testWithoutContext('all http hosts are not available', () async {
         // Run the check for all operating systems one by one
-        for(final String os in osTested) {
+        for (final String os in osTested) {
           final Platform platform = FakePlatform(operatingSystem: os);
           final HttpHostValidator httpHostValidator = HttpHostValidator(
             platform: platform,
             featureFlags: TestFeatureFlags(),
             httpClient: FakeHttpClient.list(<FakeRequest>[
-              FakeRequest(Uri.parse(kgCloudHttpHost), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
-              FakeRequest(Uri.parse(androidRequiredHttpHosts(platform)[0]), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
-              FakeRequest(Uri.parse(kPubDevHttpHost), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
-              FakeRequest(Uri.parse(macOSRequiredHttpHosts[0]), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
+              FakeRequest(Uri.parse(kCloudHost), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
+              FakeRequest(Uri.parse(kCocoaPods), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
+              FakeRequest(Uri.parse(kGitHub), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
+              FakeRequest(Uri.parse(kMaven), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
+              FakeRequest(Uri.parse(kPubDev), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
             ]),
           );
 
@@ -71,16 +70,17 @@ void main() {
 
       testWithoutContext('one http host is not available', () async {
         // Run the check for all operating systems one by one
-        for(final String os in osTested) {
+        for (final String os in osTested) {
           final Platform platform = FakePlatform(operatingSystem: os);
           final HttpHostValidator httpHostValidator = HttpHostValidator(
             platform: platform,
             featureFlags: TestFeatureFlags(),
             httpClient: FakeHttpClient.list(<FakeRequest>[
-              FakeRequest(Uri.parse(kgCloudHttpHost), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
-              FakeRequest(Uri.parse(androidRequiredHttpHosts(platform)[0]), method: HttpMethod.head),
-              FakeRequest(Uri.parse(kPubDevHttpHost), method: HttpMethod.head),
-              FakeRequest(Uri.parse(macOSRequiredHttpHosts[0]), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kCloudHost), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
+              FakeRequest(Uri.parse(kCocoaPods), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kGitHub), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kMaven), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kPubDev), method: HttpMethod.head),
             ]),
           );
 
@@ -98,7 +98,7 @@ void main() {
         final FakeHttpClient mockClient = FakeHttpClient.any();
 
         // Run the check for all operating systems one by one
-        for(final String os in osTested) {
+        for (final String os in osTested) {
           final HttpHostValidator httpHostValidator = HttpHostValidator(
             platform: FakePlatform(operatingSystem: os, environment: kTestEnvironment),
             featureFlags: TestFeatureFlags(),
@@ -115,15 +115,16 @@ void main() {
 
       testWithoutContext('all http hosts are not available', () async {
         // Run the check for all operating systems one by one
-        for(final String os in osTested) {
+        for (final String os in osTested) {
           final Platform platform = FakePlatform(operatingSystem: os, environment: kTestEnvironment);
           final HttpHostValidator httpHostValidator = HttpHostValidator(
             platform: platform,
             featureFlags: TestFeatureFlags(),
             httpClient: FakeHttpClient.list(<FakeRequest>[
+              FakeRequest(Uri.parse(kCocoaPods), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
+              FakeRequest(Uri.parse(kGitHub), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
               FakeRequest(Uri.parse(kTestEnvGCloudHost), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
               FakeRequest(Uri.parse(kTestEnvPubHost), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
-              FakeRequest(Uri.parse(macOSRequiredHttpHosts[0]), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
             ]),
           );
 
@@ -137,15 +138,16 @@ void main() {
 
       testWithoutContext('one http host is not available', () async {
         // Run the check for all operating systems one by one
-        for(final String os in osTested) {
+        for (final String os in osTested) {
           final Platform platform = FakePlatform(operatingSystem: os, environment: kTestEnvironment);
           final HttpHostValidator httpHostValidator = HttpHostValidator(
             platform: platform,
             featureFlags: TestFeatureFlags(),
             httpClient: FakeHttpClient.list(<FakeRequest>[
+              FakeRequest(Uri.parse(kCocoaPods), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kGitHub), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
               FakeRequest(Uri.parse(kTestEnvGCloudHost), method: HttpMethod.head, responseError: const OSError('Name or service not known', -2)),
               FakeRequest(Uri.parse(kTestEnvPubHost), method: HttpMethod.head),
-              FakeRequest(Uri.parse(macOSRequiredHttpHosts[0]), method: HttpMethod.head),
             ]),
           );
 
@@ -157,39 +159,12 @@ void main() {
         }
       });
 
-      testWithoutContext('does not throw on invalid user-defined timeout', () async {
-        final HttpHostValidator httpHostValidator = HttpHostValidator(
-          platform: FakePlatform(
-            environment: <String,String> {
-              'PUB_HOSTED_URL': kTestEnvPubHost,
-              'FLUTTER_STORAGE_BASE_URL': kTestEnvGCloudHost,
-              'FLUTTER_DOCTOR_HOST_TIMEOUT' : 'deadbeef',
-            },
-          ),
-          featureFlags: TestFeatureFlags(isAndroidEnabled: false),
-          httpClient: FakeHttpClient.any(),
-        );
-
-        // Run the validation check and get the results
-        final ValidationResult result = await httpHostValidator.validate();
-
-        expect(result.type, equals(ValidationType.notAvailable));
-        expect(
-          result.messages,
-          contains(const ValidationMessage.error(
-            'HTTP host "$kTestEnvPubHost" is not reachable. '
-            'Reason: The value of FLUTTER_DOCTOR_HOST_TIMEOUT(deadbeef) is not a valid duration in seconds',
-          )),
-        );
-      });
-
       testWithoutContext('does not throw on unparseable user-defined host uri', () async {
         final HttpHostValidator httpHostValidator = HttpHostValidator(
           platform: FakePlatform(
             environment: <String,String> {
               'PUB_HOSTED_URL': '::Not A Uri::',
               'FLUTTER_STORAGE_BASE_URL': kTestEnvGCloudHost,
-              'FLUTTER_DOCTOR_HOST_TIMEOUT' : '1',
             },
           ),
           featureFlags: TestFeatureFlags(isAndroidEnabled: false),
@@ -203,8 +178,8 @@ void main() {
         expect(
           result.messages,
           contains(const ValidationMessage.error(
-            'HTTP host "::Not A Uri::" is not reachable. '
-            'Reason: The value of PUB_HOSTED_URL(::Not A Uri::) could not be parsed as a valid url',
+            'Environment variable PUB_HOSTED_URL does not specify a valid URL: "::Not A Uri::"\n'
+            'Please see https://flutter.dev/community/china for an example of how to use it.',
           )),
         );
       });
@@ -215,7 +190,6 @@ void main() {
             environment: <String,String> {
               'PUB_HOSTED_URL': kTestEnvPubHost,
               'FLUTTER_STORAGE_BASE_URL': '',
-              'FLUTTER_DOCTOR_HOST_TIMEOUT' : '1',
             },
           ),
           featureFlags: TestFeatureFlags(isAndroidEnabled: false),
@@ -229,8 +203,8 @@ void main() {
         expect(
           result.messages,
           contains(const ValidationMessage.error(
-            'HTTP host "" is not reachable. '
-            'Reason: The value of FLUTTER_STORAGE_BASE_URL() is not a valid host',
+            'Environment variable FLUTTER_STORAGE_BASE_URL does not specify a valid URL: ""\n'
+            'Please see https://flutter.dev/community/china for an example of how to use it.'
           )),
         );
       });
@@ -239,14 +213,15 @@ void main() {
     group('specific os disabled', () {
       testWithoutContext('all http hosts are available - android disabled', () async {
         // Run the check for all operating systems one by one
-        for(final String os in osTested) {
+        for (final String os in osTested) {
           final HttpHostValidator httpHostValidator = HttpHostValidator(
             platform: FakePlatform(operatingSystem: os),
             featureFlags: TestFeatureFlags(isAndroidEnabled: false),
             httpClient: FakeHttpClient.list(<FakeRequest>[
-              FakeRequest(Uri.parse(kgCloudHttpHost), method: HttpMethod.head),
-              FakeRequest(Uri.parse(kPubDevHttpHost), method: HttpMethod.head),
-              FakeRequest(Uri.parse(macOSRequiredHttpHosts[0]), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kCloudHost), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kCocoaPods), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kGitHub), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kPubDev), method: HttpMethod.head),
             ]),
           );
 
@@ -260,15 +235,16 @@ void main() {
 
       testWithoutContext('all http hosts are available - iOS disabled', () async {
         // Run the check for all operating systems one by one
-        for(final String os in osTested) {
+        for (final String os in osTested) {
           final Platform platform = FakePlatform(operatingSystem: os);
           final HttpHostValidator httpHostValidator = HttpHostValidator(
             platform: platform,
             featureFlags: TestFeatureFlags(isIOSEnabled: false),
             httpClient: FakeHttpClient.list(<FakeRequest>[
-              FakeRequest(Uri.parse(kgCloudHttpHost), method: HttpMethod.head),
-              FakeRequest(Uri.parse(kPubDevHttpHost), method: HttpMethod.head),
-              FakeRequest(Uri.parse(androidRequiredHttpHosts(platform)[0]), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kCloudHost), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kGitHub), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kMaven), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kPubDev), method: HttpMethod.head),
             ]),
           );
 
@@ -282,13 +258,14 @@ void main() {
 
       testWithoutContext('all http hosts are available - android, iOS disabled', () async {
         // Run the check for all operating systems one by one
-        for(final String os in osTested) {
+        for (final String os in osTested) {
           final HttpHostValidator httpHostValidator = HttpHostValidator(
             platform: FakePlatform(operatingSystem: os),
             featureFlags: TestFeatureFlags(isAndroidEnabled: false, isIOSEnabled: false),
             httpClient: FakeHttpClient.list(<FakeRequest>[
-              FakeRequest(Uri.parse(kgCloudHttpHost), method: HttpMethod.head),
-              FakeRequest(Uri.parse(kPubDevHttpHost), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kCloudHost), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kGitHub), method: HttpMethod.head),
+              FakeRequest(Uri.parse(kPubDev), method: HttpMethod.head),
             ]),
           );
 
@@ -320,6 +297,7 @@ Handshake error in client (OS Error:
           responseError: const HandshakeException(handshakeMessage),
         ),
         FakeRequest(Uri.parse(kTestEnvGCloudHost), method: HttpMethod.head),
+        FakeRequest(Uri.parse(kGitHub), method: HttpMethod.head),
       ]),
     );
 
@@ -335,24 +313,4 @@ Handshake error in client (OS Error:
       ),
     );
   });
-
-  testWithoutContext('Http host validator timeout message includes timeout duration.', () async {
-    final HttpHostValidator httpHostValidator = HttpHostValidator(
-      platform: FakePlatform(environment: kTestEnvironment),
-      featureFlags: TestFeatureFlags(isAndroidEnabled: false),
-      httpClient: FakeHttpClient.list(<FakeRequest>[
-        FakeRequest(Uri.parse(kTestEnvPubHost), method: HttpMethod.head, responseError: TimeoutException('Timeout error')),
-        FakeRequest(Uri.parse(kTestEnvGCloudHost), method: HttpMethod.head),
-      ]),
-    );
-
-    // Run the validation check and get the results
-    final ValidationResult result = await httpHostValidator.validate();
-
-    // Timeout duration for tests is set to 1 second
-    expect(
-      result.messages,
-      contains(const ValidationMessage.error('HTTP host "$kTestEnvPubHost" is not reachable. Reason: Failed to connect to host in 1 second')),
-    );
-  });
 }

packages/flutter_tools/test/general.shard/base/logger_test.dart

@@ -497,10 +497,7 @@ void main() {
             time.elapse(timeLapse);
 
             List<String> lines = outputStdout();
-            expect(
-              lines.join(),
-              contains(warningMessage),
-            );
+            expect(lines.join(), '⣽\ba warning message.⣻');
 
             spinner.stop();
             lines = outputStdout();