Test Linux's FlView, and that Keyboard state is reset when engine restarts

[dkwingsmt]

We could not find a way to unit test the FlView as of 10/5/2021 (97f027), because most of its code can't be run headlessly. We should add a regression test for flutter/engine#28877 with the following step:

App: any app.

Steps:

1. Run with flutter run -d linux
2. Press ShiftLeft and hold
3. Hot restart the app

• If run mannually, use the mouse to focus the terminal's window, then press R to hot restart. (You can release ShiftLeft now.)

4. Switch back to the restarted app, press any key.

Expected: the key press is processed normally.

Actual: The app crashes with the following log:

══╡ EXCEPTION CAUGHT BY SERVICES LIBRARY ╞══════════════════════════════════════════════════════════
The following assertion was thrown during a platform message callback:
A KeyUpEvent is dispatched, but the state shows that the physical key is not pressed. If this occurs
in real application, please report this bug to Flutter. If this occurs in unit tests, please ensure
that simulated events follow Flutter's event model as documented in `HardwareKeyboard`. This was the
event: KeyUpEvent#4bf2a(physicalKey: PhysicalKeyboardKey#700e1(usbHidUsage: "0x000700e1", debugName:
"Shift Left"), logicalKey: LogicalKeyboardKey#00102(keyId: "0x200000102", keyLabel: "Shift Left",
debugName: "Shift Left"), character: null, timeStamp: 542:07:44.112000, synthesized)
'package:flutter/src/services/hardware_keyboard.dart':
Failed assertion: line 441 pos 16: '_pressedKeys.containsKey(event.physicalKey)'
Either the assertion indicates an error in the framework itself, or we should provide substantially

more information in this error message to help you determine and fix the underlying cause.

In either case, please report this assertion by filing a bug on GitHub:

https://github.com/flutter/flutter/issues/new?template=2_bug.md
When the exception was thrown, this was the stack:

#2      HardwareKeyboard._assertEventIsRegular.

(package:flutter/src/services/hardware_keyboard.dart:441:16)

#3      HardwareKeyboard._assertEventIsRegular (package:flutter/src/services/hardware_keyboard.dart:452:6)

#4      HardwareKeyboard.handleKeyEvent (package:flutter/src/services/hardware_keyboard.dart:543:5)

#5      KeyEventManager.handleRawKeyMessage (package:flutter/src/services/hardware_keyboard.dart:821:35)

#6      BasicMessageChannel.setMessageHandler.

(package:flutter/src/services/platform_channel.dart:77:49)

#7      BasicMessageChannel.setMessageHandler.

(package:flutter/src/services/platform_channel.dart:76:47)

#8      _DefaultBinaryMessenger.setMessageHandler.

(package:flutter/src/services/binding.dart:386:35)

#9      _DefaultBinaryMessenger.setMessageHandler.

(package:flutter/src/services/binding.dart:383:46)

#10     _invoke2. (dart:ui/hooks.dart:205:15)

#14     _invoke2 (dart:ui/hooks.dart:204:10)

#15     _ChannelCallbackRecord.invoke (dart:ui/channel_buffers.dart:42:5)

#16     _Channel.push (dart:ui/channel_buffers.dart:132:31)

#17     ChannelBuffers.push (dart:ui/channel_buffers.dart:329:17)

#18     PlatformDispatcher._dispatchPlatformMessage (dart:ui/platform_dispatcher.dart:544:22)

#19     _dispatchPlatformMessage (dart:ui/hooks.dart:92:31)

(elided 5 frames from class _AssertionError and dart:async)

════════════════════════════════════════════════════════════════════════════════════════════════════
** (test_app:594560): WARNING **: 23:43:36.514: Unable to retrieve framework response: Message is not valid JSON
Another exception was thrown: A KeyUpEvent is dispatched, but the state shows that the physical key is not

pressed. If this occurs in real application, please report this bug to Flutter. If this occurs in unit tests,

please ensure that simulated events follow Flutter's event model as documented in HardwareKeyboard. This was

the event: KeyUpEvent#4bf2a(physicalKey: PhysicalKeyboardKey#700e1(usbHidUsage: "0x000700e1", debugName:

"Shift Left"), logicalKey: LogicalKeyboardKey#00102(keyId: "0x200000102", keyLabel: "Shift Left", debugName:

"Shift Left"), character: null, timeStamp: 542:07:44.112000, synthesized)

Note: This crash relies on the assertion on KeyEvent here.

[TahaTesser]

Thanks for filing the issue!

logs

Restarted application in 504ms.
** (triage:7542): WARNING **: 10:48:20.399: Unable to retrieve framework response: Message is not valid JSON

════════ Exception caught by services library ══════════════════════════════════
The following assertion was thrown during a platform message callback:
A KeyUpEvent is dispatched, but the state shows that the physical key is not pressed. If this occurs in real application, please report this bug to Flutter. If this occurs in unit tests, please ensure that simulated events follow Flutter's event model as documented in `HardwareKeyboard`. This was the event: KeyUpEvent#f85ae(physicalKey: PhysicalKeyboardKey#700e1(usbHidUsage: "0x000700e1", debugName: "Shift Left"), logicalKey: LogicalKeyboardKey#00102(keyId: "0x200000102", keyLabel: "Shift Left", debugName: "Shift Left"), character: null, timeStamp: 1:06:31.888000)
'package:flutter/src/services/hardware_keyboard.dart':
Failed assertion: line 441 pos 16: '_pressedKeys.containsKey(event.physicalKey)'


Either the assertion indicates an error in the framework itself, or we should provide substantially more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
  https://github.com/flutter/flutter/issues/new?template=2_bug.md

When the exception was thrown, this was the stack
#2      HardwareKeyboard._assertEventIsRegular.<anonymous closure>
#3      HardwareKeyboard._assertEventIsRegular
#4      HardwareKeyboard.handleKeyEvent
#5      KeyEventManager.handleRawKeyMessage
#6      BasicMessageChannel.setMessageHandler.<anonymous closure>
#7      BasicMessageChannel.setMessageHandler.<anonymous closure>
#8      _DefaultBinaryMessenger.setMessageHandler.<anonymous closure>
#9      _DefaultBinaryMessenger.setMessageHandler.<anonymous closure>
#10     _invoke2.<anonymous closure> (dart:ui/hooks.dart:189:15)
#14     _invoke2 (dart:ui/hooks.dart:188:10)
#15     _ChannelCallbackRecord.invoke (dart:ui/channel_buffers.dart:42:5)
#16     _Channel.push (dart:ui/channel_buffers.dart:132:31)
#17     ChannelBuffers.push (dart:ui/channel_buffers.dart:329:17)
#18     PlatformDispatcher._dispatchPlatformMessage (dart:ui/platform_dispatcher.dart:544:22)
#19     _dispatchPlatformMessage (dart:ui/hooks.dart:83:31)
(elided 5 frames from class _AssertionError and dart:async)
════════════════════════════════════════════════════════════════════════════════
** (triage:7542): WARNING **: 10:48:20.446: Unable to retrieve framework response: Message is not valid JSON

════════ Exception caught by services library ══════════════════════════════════
A KeyUpEvent is dispatched, but the state shows that the physical key is not pressed. If this occurs in real application, please report this bug to Flutter. If this occurs in unit tests, please ensure that simulated events follow Flutter's event model as documented in `HardwareKeyboard`. This was the event: KeyUpEvent#f85ae(physicalKey: PhysicalKeyboardKey#700e1(usbHidUsage: "0x000700e1", debugName: "Shift Left"), logicalKey: LogicalKeyboardKey#00102(keyId: "0x200000102", keyLabel: "Shift Left", debugName: "Shift Left"), character: null, timeStamp: 1:06:31.888000)
'package:flutter/src/services/hardware_keyboard.dart':
Failed assertion: line 441 pos 16: '_pressedKeys.containsKey(event.physicalKey)'

════════════════════════════════════════════════════════════════════════════════
** (triage:7542): WARNING **: 10:48:21.465: Unable to retrieve framework response: Message is not valid JSON

════════ Exception caught by services library ══════════════════════════════════
A KeyUpEvent is dispatched, but the state shows that the physical key is not pressed. If this occurs in real application, please report this bug to Flutter. If this occurs in unit tests, please ensure that simulated events follow Flutter's event model as documented in `HardwareKeyboard`. This was the event: KeyUpEvent#f85ae(physicalKey: PhysicalKeyboardKey#700e1(usbHidUsage: "0x000700e1", debugName: "Shift Left"), logicalKey: LogicalKeyboardKey#00102(keyId: "0x200000102", keyLabel: "Shift Left", debugName: "Shift Left"), character: null, timeStamp: 1:06:31.888000)
'package:flutter/src/services/hardware_keyboard.dart':
Failed assertion: line 441 pos 16: '_pressedKeys.containsKey(event.physicalKey)'

════════════════════════════════════════════════════════════════════════════════

stable	master
❗️	❗️

Check flutter doctor -v outputs for each channel below

flutter doctor -v

[✓] Flutter (Channel stable, 2.5.2, on Zorin OS 16 5.11.0-37-generic, locale en_US.UTF-8)
    • Flutter version 2.5.2 at /home/taha/Code/flutter_stable
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 3595343e20 (6 days ago), 2021-09-30 12:58:18 -0700
    • Engine revision 6ac856380f
    • Dart version 2.14.3

[✓] Android toolchain - develop for Android devices (Android SDK version 31.0.0)
    • Android SDK at /home/taha/Code/android-sdk
    • Platform android-31, build-tools 31.0.0
    • ANDROID_SDK_ROOT = /home/taha/Code/android-sdk
    • Java binary at: /home/taha/Code/android-studio/jre/bin/java
    • Java version OpenJDK Runtime Environment (build 11.0.10+0-b96-7249189)
    • All Android licenses accepted.

[✓] Chrome - develop for the web
    • Chrome at google-chrome

[✓] Linux toolchain - develop for Linux desktop
    • clang version 10.0.0-4ubuntu1
    • cmake version 3.16.3
    • ninja version 1.8.2
    • pkg-config version 0.29.1

[✓] Android Studio (version 2020.3)
    • Android Studio at /home/taha/Code/android-studio
    • Flutter plugin version 60.1.2
    • Dart plugin version 203.8292
    • Java version OpenJDK Runtime Environment (build 11.0.10+0-b96-7249189)

[✓] VS Code
    • VS Code at /snap/code/current
    • Flutter extension version 3.27.0

[✓] Connected device (2 available)
    • Linux (desktop) • linux  • linux-x64      • Zorin OS 16 5.11.0-37-generic
    • Chrome (web)    • chrome • web-javascript • Google Chrome 94.0.4606.71

• No issues found!

[✓] Flutter (Channel master, 2.6.0-12.0.pre.218, on Zorin OS 16 5.11.0-37-generic, locale en_US.UTF-8)
    • Flutter version 2.6.0-12.0.pre.218 at /home/taha/Code/flutter_master
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 39f5769cd8 (41 minutes ago), 2021-10-06 08:10:37 +0100
    • Engine revision 88e150ddc9
    • Dart version 2.15.0 (build 2.15.0-178.0.dev)

[✓] Android toolchain - develop for Android devices (Android SDK version 31.0.0)
    • Android SDK at /home/taha/Code/android-sdk
    • Platform android-31, build-tools 31.0.0
    • ANDROID_SDK_ROOT = /home/taha/Code/android-sdk
    • Java binary at: /home/taha/Code/android-studio/jre/bin/java
    • Java version OpenJDK Runtime Environment (build 11.0.10+0-b96-7249189)
    • All Android licenses accepted.

[✓] Chrome - develop for the web
    • Chrome at google-chrome

[✓] Linux toolchain - develop for Linux desktop
    • clang version 10.0.0-4ubuntu1
    • cmake version 3.16.3
    • ninja version 1.8.2
    • pkg-config version 0.29.1

[✓] Android Studio (version 2020.3)
    • Android Studio at /home/taha/Code/android-studio
    • Flutter plugin version 60.1.2
    • Dart plugin version 203.8292
    • Java version OpenJDK Runtime Environment (build 11.0.10+0-b96-7249189)

[✓] VS Code
    • VS Code at /snap/code/current
    • Flutter extension version 3.27.0

[✓] Connected device (2 available)
    • Linux (desktop) • linux  • linux-x64      • Zorin OS 16 5.11.0-37-generic
    • Chrome (web)    • chrome • web-javascript • Google Chrome 94.0.4606.71

• No issues found!

✅: No Issue ❗️: Issue reproduced

Related #89729