Clearer text about what happens with `--disable-telemetry` + enable-telemetry command (#125995)

Fixes:
- https://github.com/flutter/flutter/issues/124411

This PR is cleaning up the `--disable-telemetry` help message to make it clear that opting out will opt out of all telemetry collection for flutter and dart commands. It is also adding the opposite flag `--enable-telemetry` which will enable telemetry collection

packages/flutter_tools/lib/runner.dart

@@ -63,31 +63,55 @@ Future<int> run(
     StackTrace? firstStackTrace;
     return runZoned<Future<int>>(() async {
       try {
+        if (args.contains('--disable-telemetry') &&
+            args.contains('--enable-telemetry')) {
+          throwToolExit(
+              'Both enable and disable telemetry commands were detected '
+              'when only one can be supplied per invocation.',
+              exitCode: 1);
+        }
+
         // Disable analytics if user passes in the `--disable-telemetry` option
         // `flutter --disable-telemetry`
         //
         // Same functionality as `flutter config --no-analytics` for disabling
         // except with the `value` hard coded as false
         if (args.contains('--disable-telemetry')) {
-          const bool value = false;
           // The tool sends the analytics event *before* toggling the flag
           // intentionally to be sure that opt-out events are sent correctly.
-          AnalyticsConfigEvent(enabled: value).send();
-          if (!value) {
-            // Normally, the tool waits for the analytics to all send before the
-            // tool exits, but only when analytics are enabled. When reporting that
-            // analytics have been disable, the wait must be done here instead.
-            await globals.flutterUsage.ensureAnalyticsSent();
-          }
-          globals.flutterUsage.enabled = value;
+          AnalyticsConfigEvent(enabled: false).send();
+
+          // Normally, the tool waits for the analytics to all send before the
+          // tool exits, but only when analytics are enabled. When reporting that
+          // analytics have been disable, the wait must be done here instead.
+          await globals.flutterUsage.ensureAnalyticsSent();
+
+          globals.flutterUsage.enabled = false;
           globals.printStatus('Analytics reporting disabled.');
 
           // TODO(eliasyishak): Set the telemetry for the unified_analytics
           //  package as well, the above will be removed once we have
           //  fully transitioned to using the new package
-          await globals.analytics.setTelemetry(value);
+          await globals.analytics.setTelemetry(false);
+        }
+
+        // Enable analytics if user passes in the `--enable-telemetry` option
+        // `flutter --enable-telemetry`
+        //
+        // Same functionality as `flutter config --analytics` for enabling
+        // except with the `value` hard coded as true
+        if (args.contains('--enable-telemetry')) {
+          // The tool sends the analytics event *before* toggling the flag
+          // intentionally to be sure that opt-out events are sent correctly.
+          AnalyticsConfigEvent(enabled: true).send();
+
+          globals.flutterUsage.enabled = true;
+          globals.printStatus('Analytics reporting enabled.');
+
+          await globals.analytics.setTelemetry(true);
         }
 
+
         await runner.run(args);
 
         // Triggering [runZoned]'s error callback does not necessarily mean that

packages/flutter_tools/lib/src/runner/flutter_command_runner.dart

@@ -80,7 +80,12 @@ class FlutterCommandRunner extends CommandRunner<void> {
         help: 'Suppress analytics reporting for the current CLI invocation.');
     argParser.addFlag('disable-telemetry',
         negatable: false,
-        help: 'Disable telemetry reporting when this command runs.');
+        help: 'Disable telemetry reporting each time a flutter or dart '
+              'command runs, until it is re-enabled.');
+    argParser.addFlag('enable-telemetry',
+        negatable: false,
+        help: 'Enable telemetry reporting each time a flutter or dart '
+              'command runs.');
     argParser.addOption('packages',
         hide: !verboseHelp,
         help: 'Path to your "package_config.json" file.');
@@ -188,8 +193,10 @@ class FlutterCommandRunner extends CommandRunner<void> {
   Future<void> runCommand(ArgResults topLevelResults) async {
     final Map<Type, Object?> contextOverrides = <Type, Object?>{};
 
-    // If the disable-telemetry flag has been passed, return out
-    if (topLevelResults.wasParsed('disable-telemetry')) {
+    // If the flag for enabling or disabling telemetry is passed in,
+    // we will return out
+    if (topLevelResults.wasParsed('disable-telemetry') ||
+        topLevelResults.wasParsed('enable-telemetry')) {
       return;
     }
 

packages/flutter_tools/test/general.shard/runner/runner_test.dart

@@ -317,11 +317,6 @@ void main() {
   });
 
   group('unified_analytics', () {
-    final Usage legacyAnalytics = TestUsage();
-    setUp(() {
-      legacyAnalytics.enabled = false;
-    });
-
     testUsingContext(
       'runner disable telemetry with flag',
       () async {
@@ -346,6 +341,62 @@ void main() {
         ProcessManager: () => FakeProcessManager.any(),
       },
     );
+
+    testUsingContext(
+      'runner enabling telemetry with flag',
+      () async {
+        io.setExitFunctionForTests((int exitCode) {});
+
+        expect(globals.analytics.telemetryEnabled, false);
+        expect(globals.analytics.shouldShowMessage, false);
+
+        await runner.run(
+          <String>['--enable-telemetry'],
+          () => <FlutterCommand>[],
+          // This flutterVersion disables crash reporting.
+          flutterVersion: '[user-branch]/',
+          shutdownHooks: ShutdownHooks(),
+        );
+
+        expect(globals.analytics.telemetryEnabled, true);
+      },
+      overrides: <Type, Generator>{
+        Analytics: () => FakeAnalytics(fakeTelemetryStatusOverride: false),
+        FileSystem: () => MemoryFileSystem.test(),
+        ProcessManager: () => FakeProcessManager.any(),
+      },
+    );
+
+    testUsingContext(
+      'throw error when both flags passed',
+      () async {
+        io.setExitFunctionForTests((int exitCode) {});
+
+        expect(globals.analytics.telemetryEnabled, true);
+        expect(globals.analytics.shouldShowMessage, true);
+
+        final int exitCode = await runner.run(
+          <String>[
+            '--disable-telemetry',
+            '--enable-telemetry',
+          ],
+          () => <FlutterCommand>[],
+          // This flutterVersion disables crash reporting.
+          flutterVersion: '[user-branch]/',
+          shutdownHooks: ShutdownHooks(),
+        );
+
+        expect(exitCode, 1,
+            reason: 'Should return 1 due to conflicting options for telemetry');
+        expect(globals.analytics.telemetryEnabled, true,
+            reason: 'Should not have changed from initialization');
+      },
+      overrides: <Type, Generator>{
+        Analytics: () => FakeAnalytics(),
+        FileSystem: () => MemoryFileSystem.test(),
+        ProcessManager: () => FakeProcessManager.any(),
+      },
+    );
   });
 }
 
@@ -489,8 +540,16 @@ class WaitingCrashReporter implements CrashReporter {
 /// A fake [Analytics] that will be used to test
 /// the --disable-telemetry flag
 class FakeAnalytics extends Fake implements Analytics {
-  bool _fakeTelemetryStatus = true;
-  bool _fakeShowMessage = true;
+
+  FakeAnalytics({bool fakeTelemetryStatusOverride = true})
+      : _fakeTelemetryStatus = fakeTelemetryStatusOverride,
+        _fakeShowMessage = fakeTelemetryStatusOverride;
+
+  // Both of the members below can be initialized with [fakeTelemetryStatusOverride]
+  // because if we pass in false for the status, that means we can also
+  // assume the message has been shown before
+  bool _fakeTelemetryStatus;
+  bool _fakeShowMessage;
 
   @override
   String get getConsentMessage => 'message';