[flutter_tools] Handle errors on the std{out,err}.done future

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

@@ -42,6 +42,7 @@ import 'dart:io' as io
     Stdin,
     StdinException,
     Stdout,
+    StdoutException,
     stdout;
 
 import 'package:meta/meta.dart';
@@ -208,16 +209,64 @@ class _PosixProcessSignal extends ProcessSignal {
 
 /// A class that wraps stdout, stderr, and stdin, and exposes the allowed
 /// operations.
+///
+/// In particular, there are three ways that writing to stdout and stderr
+/// can fail. A call to stdout.write() can fail:
+///   * by throwing a regular synchronous exception,
+///   * by throwing an exception asynchronously, and
+///   * by completing the Future stdout.done with an error.
+///
+/// This class enapsulates all three so that we don't have to worry about it
+/// anywhere else.
 class Stdio {
-  const Stdio();
+  Stdio();
+
+  /// Tests can provide overrides to use instead of the stdout and stderr from
+  /// dart:io.
+  @visibleForTesting
+  Stdio.test({
+    @required io.Stdout stdout,
+    @required io.IOSink stderr,
+  }) : _stdoutOverride = stdout, _stderrOverride = stderr;
+
+  io.Stdout _stdoutOverride;
+  io.IOSink _stderrOverride;
+
+  // These flags exist to remember when the done Futures on stdout and stderr
+  // complete to avoid trying to write to a closed stream sink, which would
+  // generate a [StateError].
+  bool _stdoutDone = false;
+  bool _stderrDone = false;
 
   Stream<List<int>> get stdin => io.stdin;
 
   @visibleForTesting
-  io.Stdout get stdout => io.stdout;
+  io.Stdout get stdout {
+    if (_stdout != null) {
+      return _stdout;
+    }
+    _stdout = _stdoutOverride ?? io.stdout;
+    _stdout.done.then(
+      (void _) { _stdoutDone = true; },
+      onError: (Object err, StackTrace st) { _stdoutDone = true; },
+    );
+    return _stdout;
+  }
+  io.Stdout _stdout;
 
   @visibleForTesting
-  io.IOSink get stderr => io.stderr;
+  io.IOSink get stderr {
+    if (_stderr != null) {
+      return _stderr;
+    }
+    _stderr = _stderrOverride ?? io.stderr;
+    _stderr.done.then(
+      (void _) { _stderrDone = true; },
+      onError: (Object err, StackTrace st) { _stderrDone = true; },
+    );
+    return _stderr;
+  }
+  io.IOSink _stderr;
 
   bool get hasTerminal => io.stdout.hasTerminal;
 
@@ -250,25 +299,45 @@ class Stdio {
     return _stdinHasTerminal = true;
   }
 
-  int get terminalColumns => hasTerminal ? io.stdout.terminalColumns : null;
-  int get terminalLines => hasTerminal ? io.stdout.terminalLines : null;
-  bool get supportsAnsiEscapes => hasTerminal && io.stdout.supportsAnsiEscapes;
+  int get terminalColumns => hasTerminal ? stdout.terminalColumns : null;
+  int get terminalLines => hasTerminal ? stdout.terminalLines : null;
+  bool get supportsAnsiEscapes => hasTerminal && stdout.supportsAnsiEscapes;
 
   /// Writes [message] to [stderr], falling back on [fallback] if the write
   /// throws any exception. The default fallback calls [print] on [message].
   void stderrWrite(
     String message, {
     void Function(String, dynamic, StackTrace) fallback,
-  }) => _stdioWrite(stderr, message, fallback: fallback);
+  }) {
+    if (!_stderrDone) {
+      _stdioWrite(stderr, message, fallback: fallback);
+      return;
+    }
+    fallback == null ? print(message) : fallback(
+      message,
+      const io.StdoutException('stderr is done'),
+      StackTrace.current,
+    );
+  }
 
   /// Writes [message] to [stdout], falling back on [fallback] if the write
   /// throws any exception. The default fallback calls [print] on [message].
   void stdoutWrite(
     String message, {
     void Function(String, dynamic, StackTrace) fallback,
-  }) => _stdioWrite(stdout, message, fallback: fallback);
+  }) {
+    if (!_stdoutDone) {
+      _stdioWrite(stdout, message, fallback: fallback);
+      return;
+    }
+    fallback == null ? print(message) : fallback(
+      message,
+      const io.StdoutException('stdout is done'),
+      StackTrace.current,
+    );
+  }
 
-  // Helper for safeStderrWrite and safeStdoutWrite.
+  // Helper for [stderrWrite] and [stdoutWrite].
   void _stdioWrite(io.IOSink sink, String message, {
     void Function(String, dynamic, StackTrace) fallback,
   }) {

packages/flutter_tools/lib/src/context_runner.dart

@@ -175,7 +175,7 @@ Future<T> runInContext<T>(
       ShutdownHooks: () => ShutdownHooks(logger: globals.logger),
       Signals: () => Signals(),
       SimControl: () => SimControl(),
-      Stdio: () => const Stdio(),
+      Stdio: () => Stdio(),
       SystemClock: () => const SystemClock(),
       TimeoutConfiguration: () => const TimeoutConfiguration(),
       Usage: () => Usage(

packages/flutter_tools/lib/src/globals.dart

@@ -150,14 +150,16 @@ final AnsiTerminal _defaultAnsiTerminal = AnsiTerminal(
 );
 
 /// The global Stdio wrapper.
-Stdio get stdio => context.get<Stdio>() ?? const Stdio();
-
-PlistParser get plistParser => context.get<PlistParser>() ?? (_defaultInstance ??= PlistParser(
-  fileSystem: fs,
-  processManager: processManager,
-  logger: logger,
+Stdio get stdio => context.get<Stdio>() ?? (_stdioInstance ??= Stdio());
+Stdio _stdioInstance;
+
+PlistParser get plistParser => context.get<PlistParser>() ?? (
+  _plistInstance ??= PlistParser(
+    fileSystem: fs,
+    processManager: processManager,
+    logger: logger,
 ));
-PlistParser _defaultInstance;
+PlistParser _plistInstance;
 
 /// The [ChromeLauncher] instance.
 ChromeLauncher get chromeLauncher => context.get<ChromeLauncher>();

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

@@ -23,16 +23,6 @@ final String resetColor = RegExp.escape(AnsiTerminal.resetColor);
 
 class MockStdout extends Mock implements Stdout {}
 
-class ThrowingStdio extends Stdio {
-  ThrowingStdio(this.stdout, this.stderr);
-
-  @override
-  final Stdout stdout;
-
-  @override
-  final IOSink stderr;
-}
-
 void main() {
   group('AppContext', () {
     FakeStopwatch fakeStopWatch;
@@ -94,9 +84,11 @@ void main() {
   testWithoutContext('Logger does not throw when stdio write throws synchronously', () async {
     final MockStdout stdout = MockStdout();
     final MockStdout stderr = MockStdout();
-    final ThrowingStdio stdio = ThrowingStdio(stdout, stderr);
+    final Stdio stdio = Stdio.test(stdout: stdout, stderr: stderr);
     bool stdoutThrew = false;
     bool stderrThrew = false;
+    final Completer<void> stdoutError = Completer<void>();
+    final Completer<void> stderrError = Completer<void>();
     when(stdout.write(any)).thenAnswer((_) {
       stdoutThrew = true;
       throw 'Error';
@@ -105,6 +97,8 @@ void main() {
       stderrThrew = true;
       throw 'Error';
     });
+    when(stdout.done).thenAnswer((_) => stdoutError.future);
+    when(stderr.done).thenAnswer((_) => stderrError.future);
     final Logger logger = StdoutLogger(
       terminal: AnsiTerminal(
         stdio: stdio,
@@ -123,7 +117,9 @@ void main() {
   testWithoutContext('Logger does not throw when stdio write throws asynchronously', () async {
     final MockStdout stdout = MockStdout();
     final MockStdout stderr = MockStdout();
-    final ThrowingStdio stdio = ThrowingStdio(stdout, stderr);
+    final Stdio stdio = Stdio.test(stdout: stdout, stderr: stderr);
+    final Completer<void> stdoutError = Completer<void>();
+    final Completer<void> stderrError = Completer<void>();
     bool stdoutThrew = false;
     bool stderrThrew = false;
     final Completer<void> stdoutCompleter = Completer<void>();
@@ -142,6 +138,8 @@ void main() {
         throw 'Error';
       }, null);
     });
+    when(stdout.done).thenAnswer((_) => stdoutError.future);
+    when(stderr.done).thenAnswer((_) => stderrError.future);
     final Logger logger = StdoutLogger(
       terminal: AnsiTerminal(
         stdio: stdio,
@@ -159,6 +157,43 @@ void main() {
     expect(stderrThrew, true);
   });
 
+  testWithoutContext('Logger does not throw when stdio completes done with an error', () async {
+    final MockStdout stdout = MockStdout();
+    final MockStdout stderr = MockStdout();
+    final Stdio stdio = Stdio.test(stdout: stdout, stderr: stderr);
+    final Completer<void> stdoutError = Completer<void>();
+    final Completer<void> stderrError = Completer<void>();
+    final Completer<void> stdoutCompleter = Completer<void>();
+    final Completer<void> stderrCompleter = Completer<void>();
+    when(stdout.write(any)).thenAnswer((_) {
+      Zone.current.runUnaryGuarded<void>((_) {
+        stdoutError.completeError(Exception('Some pipe error'));
+        stdoutCompleter.complete();
+      }, null);
+    });
+    when(stderr.write(any)).thenAnswer((_) {
+      Zone.current.runUnaryGuarded<void>((_) {
+        stderrError.completeError(Exception('Some pipe error'));
+        stderrCompleter.complete();
+      }, null);
+    });
+    when(stdout.done).thenAnswer((_) => stdoutError.future);
+    when(stderr.done).thenAnswer((_) => stderrError.future);
+    final Logger logger = StdoutLogger(
+      terminal: AnsiTerminal(
+        stdio: stdio,
+        platform: _kNoAnsiPlatform,
+      ),
+      stdio: stdio,
+      outputPreferences: OutputPreferences.test(),
+      timeoutConfiguration: const TimeoutConfiguration(),
+    );
+    logger.printStatus('message');
+    logger.printError('error message');
+    await stdoutCompleter.future;
+    await stderrCompleter.future;
+  });
+
   group('Spinners', () {
     mocks.MockStdio mockStdio;
     FakeStopwatch mockStopwatch;

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

@@ -56,7 +56,7 @@ void main() {
 
       await verifyCrashReportSent(requestInfo);
     }, overrides: <Type, Generator>{
-      Stdio: () => const _NoStderr(),
+      Stdio: () => _NoStderr(),
     });
 
     testUsingContext('should print an explanatory message when there is a SocketException', () async {
@@ -77,7 +77,7 @@ void main() {
       expect(await exitCodeCompleter.future, 1);
       expect(testLogger.errorText, contains('Failed to send crash report due to a network error'));
     }, overrides: <Type, Generator>{
-      Stdio: () => const _NoStderr(),
+      Stdio: () => _NoStderr(),
     });
 
     testUsingContext('should print an explanatory message when there is an HttpException', () async {
@@ -98,7 +98,7 @@ void main() {
       expect(await exitCodeCompleter.future, 1);
       expect(testLogger.errorText, contains('Failed to send crash report due to a network error'));
     }, overrides: <Type, Generator>{
-      Stdio: () => const _NoStderr(),
+      Stdio: () => _NoStderr(),
     });
 
     testUsingContext('should send crash reports when async throws', () async {
@@ -120,7 +120,7 @@ void main() {
       expect(await exitCodeCompleter.future, 1);
       await verifyCrashReportSent(requestInfo);
     }, overrides: <Type, Generator>{
-      Stdio: () => const _NoStderr(),
+      Stdio: () => _NoStderr(),
     });
 
     testUsingContext('should send only one crash report when async throws many', () async {
@@ -151,7 +151,7 @@ void main() {
       await verifyCrashReportSent(requestInfo, crashes: 4);
     }, overrides: <Type, Generator>{
       DoctorValidatorsProvider: () => FakeDoctorValidatorsProvider(),
-      Stdio: () => const _NoStderr(),
+      Stdio: () => _NoStderr(),
     });
 
     testUsingContext('should not send a crash report if on a user-branch', () async {
@@ -183,7 +183,7 @@ void main() {
 
       expect(testLogger.traceText, isNot(contains('Crash report sent')));
     }, overrides: <Type, Generator>{
-      Stdio: () => const _NoStderr(),
+      Stdio: () => _NoStderr(),
     });
 
     testUsingContext('can override base URL', () async {
@@ -223,7 +223,7 @@ void main() {
         },
         script: Uri(scheme: 'data'),
       ),
-      Stdio: () => const _NoStderr(),
+      Stdio: () => _NoStderr(),
     });
   });
 }
@@ -400,7 +400,7 @@ class FakeDoctorValidatorsProvider implements DoctorValidatorsProvider {
 }
 
 class _NoStderr extends Stdio {
-  const _NoStderr();
+  _NoStderr();
 
   @override
   IOSink get stderr => const _NoopIOSink();

packages/flutter_tools/test/integration.shard/downgrade_upgrade_integration_test.dart

@@ -16,12 +16,13 @@ const String _kInitialVersion = 'v1.9.1+hotfix.6';
 const String _kBranch = 'stable';
 const FileSystem fileSystem = LocalFileSystem();
 const ProcessManager processManager = LocalProcessManager();
+final Stdio stdio = Stdio();
 final ProcessUtils processUtils = ProcessUtils(processManager: processManager, logger: StdoutLogger(
   terminal: AnsiTerminal(
     platform: const LocalPlatform(),
-    stdio: const Stdio(),
+    stdio: stdio,
   ),
-  stdio: const Stdio(),
+  stdio: stdio,
   outputPreferences: OutputPreferences.test(wrapText: true),
   timeoutConfiguration: const TimeoutConfiguration(),
 ));