[Linux] take first steps towards testable text input (flutter#33661)

This PR is a continuation of flutter#33111 and includes necessary changes to test the `TextInputType.setClient()` platform channel call. Testing the actual text input flow requires a mock IM context that will follow in a separate PR.

* [Linux] pass GdkWindow instead of FlView to FlTextInputPlugin
* [Linux] add MockBinaryMessenger::ReceiveMessage()
* [Linux] add test for TextInputType.setClient
* Drop the offscreen window

GdkOffscreenWindow requires display & screen which is a problem in
headless mode. Luckily, we don't really need a window instance in tests
because its only passed as a client window to the IM context which will
be mocked out when we get to tests that depend on it.

ci/licenses_golden/licenses_flutter

@@ -2216,6 +2216,7 @@ FILE: ../../../flutter/shell/platform/linux/fl_task_runner.cc
 FILE: ../../../flutter/shell/platform/linux/fl_task_runner.h
 FILE: ../../../flutter/shell/platform/linux/fl_text_input_plugin.cc
 FILE: ../../../flutter/shell/platform/linux/fl_text_input_plugin.h
+FILE: ../../../flutter/shell/platform/linux/fl_text_input_plugin_test.cc
 FILE: ../../../flutter/shell/platform/linux/fl_texture.cc
 FILE: ../../../flutter/shell/platform/linux/fl_texture_gl.cc
 FILE: ../../../flutter/shell/platform/linux/fl_texture_gl_private.h

shell/platform/linux/BUILD.gn

@@ -216,6 +216,7 @@ executable("flutter_linux_unittests") {
     "fl_standard_message_codec_test.cc",
     "fl_standard_method_codec_test.cc",
     "fl_string_codec_test.cc",
+    "fl_text_input_plugin_test.cc",
     "fl_texture_gl_test.cc",
     "fl_texture_registrar_test.cc",
     "fl_value_test.cc",

shell/platform/linux/fl_text_input_plugin.cc

@@ -85,8 +85,8 @@ struct FlTextInputPluginPrivate {
 
   flutter::TextInputModel* text_model;
 
-  // The owning Flutter view.
-  FlView* view;
+  // The owning native window.
+  GdkWindow* window;
 
   // A 4x4 matrix that maps from `EditableText` local coordinates to the
   // coordinate system of `PipelineOwner.rootNode`.
@@ -260,8 +260,7 @@ static void im_preedit_start_cb(FlTextInputPlugin* self) {
   priv->text_model->BeginComposing();
 
   // Set the native window used for system input method windows.
-  GdkWindow* window = gtk_widget_get_window(GTK_WIDGET(priv->view));
-  gtk_im_context_set_client_window(priv->im_context, window);
+  gtk_im_context_set_client_window(priv->im_context, priv->window);
 }
 
 // Signal handler for GtkIMContext::preedit-changed
@@ -420,8 +419,7 @@ static FlMethodResponse* show(FlTextInputPlugin* self) {
   }
 
   // Set the native window used for system input method windows.
-  GdkWindow* window = gtk_widget_get_window(GTK_WIDGET(priv->view));
-  gtk_im_context_set_client_window(priv->im_context, window);
+  gtk_im_context_set_client_window(priv->im_context, priv->window);
 
   gtk_im_context_focus_in(priv->im_context);
 
@@ -601,7 +599,7 @@ static void fl_text_input_plugin_dispose(GObject* object) {
     delete priv->text_model;
     priv->text_model = nullptr;
   }
-  priv->view = nullptr;
+  priv->window = nullptr;
 
   G_OBJECT_CLASS(fl_text_input_plugin_parent_class)->dispose(object);
 }
@@ -728,7 +726,7 @@ static void fl_text_input_plugin_init(FlTextInputPlugin* self) {
 
 FlTextInputPlugin* fl_text_input_plugin_new(
     FlBinaryMessenger* messenger,
-    FlView* view,
+    GdkWindow* window,
     FlTextInputPluginImFilter im_filter) {
   g_return_val_if_fail(FL_IS_BINARY_MESSENGER(messenger), nullptr);
   g_return_val_if_fail(im_filter != nullptr, nullptr);
@@ -743,7 +741,7 @@ FlTextInputPlugin* fl_text_input_plugin_new(
       fl_method_channel_new(messenger, kChannelName, FL_METHOD_CODEC(codec));
   fl_method_channel_set_method_call_handler(priv->channel, method_call_cb, self,
                                             nullptr);
-  priv->view = view;
+  priv->window = window;
   priv->im_filter = im_filter;
 
   return self;

shell/platform/linux/fl_text_input_plugin.h

@@ -5,11 +5,10 @@
 #ifndef FLUTTER_SHELL_TEXT_INPUT_LINUX_FL_TEXT_INPUT_PLUGIN_H_
 #define FLUTTER_SHELL_TEXT_INPUT_LINUX_FL_TEXT_INPUT_PLUGIN_H_
 
-#include <gdk/gdk.h>
+#include <gtk/gtk.h>
 
 #include "flutter/shell/platform/linux/fl_key_event.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_binary_messenger.h"
-#include "flutter/shell/platform/linux/public/flutter_linux/fl_view.h"
 
 /**
  * FlTextInputPluginImFilter:
@@ -51,7 +50,7 @@ struct _FlTextInputPluginClass {
 /**
  * fl_text_input_plugin_new:
  * @messenger: an #FlBinaryMessenger.
- * @view: the #FlView with which the text input plugin is associated.
+ * @window: the #GdkWindow with which the text input plugin is associated.
  * @im_filter: a function used to allow an input method to internally handle
  * key press and release events. Typically a wrap of
  * #gtk_im_context_filter_keypress. Must not be nullptr.
@@ -63,7 +62,7 @@ struct _FlTextInputPluginClass {
  */
 FlTextInputPlugin* fl_text_input_plugin_new(
     FlBinaryMessenger* messenger,
-    FlView* view,
+    GdkWindow* window,
     FlTextInputPluginImFilter im_filter);
 
 /**

shell/platform/linux/fl_text_input_plugin_test.cc

@@ -0,0 +1,85 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/linux/fl_text_input_plugin.h"
+#include "flutter/shell/platform/linux/fl_method_codec_private.h"
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_binary_messenger.h"
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_json_method_codec.h"
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_value.h"
+#include "flutter/shell/platform/linux/testing/fl_test.h"
+#include "flutter/shell/platform/linux/testing/mock_binary_messenger.h"
+#include "flutter/shell/platform/linux/testing/mock_binary_messenger_response_handle.h"
+#include "flutter/testing/testing.h"
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+
+void printTo(FlMethodResponse* response, ::std::ostream* os) {
+  *os << ::testing::PrintToString(
+      fl_method_response_get_result(response, nullptr));
+}
+
+MATCHER_P(SuccessResponse, result, "") {
+  g_autoptr(FlJsonMethodCodec) codec = fl_json_method_codec_new();
+  g_autoptr(FlMethodResponse) response =
+      fl_method_codec_decode_response(FL_METHOD_CODEC(codec), arg, nullptr);
+  if (fl_value_equal(fl_method_response_get_result(response, nullptr),
+                     result)) {
+    return true;
+  }
+  *result_listener << ::testing::PrintToString(response);
+  return false;
+}
+
+static FlValue* build_map(std::map<const gchar*, FlValue*> args) {
+  FlValue* value = fl_value_new_map();
+  for (auto it = args.begin(); it != args.end(); ++it) {
+    fl_value_set_string_take(value, it->first, it->second);
+  }
+  return value;
+}
+
+static FlValue* build_list(std::vector<FlValue*> args) {
+  FlValue* value = fl_value_new_list();
+  for (auto it = args.begin(); it != args.end(); ++it) {
+    fl_value_append_take(value, *it);
+  }
+  return value;
+}
+
+TEST(FlTextInputPluginTest, SetClient) {
+  ::testing::NiceMock<flutter::testing::MockBinaryMessenger> mock;
+  g_autoptr(FlBinaryMessenger) messenger = fl_binary_messenger_new_mock(&mock);
+  auto filter =
+      +[](GtkIMContext* im_context, gpointer gdk_event) { return false; };
+
+  fl_text_input_plugin_new(messenger, nullptr,
+                           FlTextInputPluginImFilter(filter));
+
+  EXPECT_TRUE(mock.HasMessageHandler("flutter/textinput"));
+
+  g_autoptr(FlValue) args = build_list({
+      fl_value_new_int(1),  // client id
+      build_map({
+          {"inputAction", fl_value_new_string("")},
+          {"inputType", build_map({
+                            {"name", fl_value_new_string("TextInputType.text")},
+                        })},
+          {"enableDeltaModel", fl_value_new_bool(false)},
+      }),
+  });
+
+  g_autoptr(FlJsonMethodCodec) codec = fl_json_method_codec_new();
+  g_autoptr(GBytes) message = fl_method_codec_encode_method_call(
+      FL_METHOD_CODEC(codec), "TextInput.setClient", args, nullptr);
+
+  g_autoptr(FlValue) null = fl_value_new_null();
+  EXPECT_CALL(mock, fl_binary_messenger_send_response(
+                        ::testing::Eq(messenger),
+                        ::testing::A<FlBinaryMessengerResponseHandle*>(),
+                        SuccessResponse(null), ::testing::A<GError**>()))
+      .WillOnce(::testing::Return(true));
+
+  mock.ReceiveMessage(messenger, "flutter/textinput", message);
+}

shell/platform/linux/fl_view.cc

@@ -103,8 +103,9 @@ static gboolean text_input_im_filter_by_gtk(GtkIMContext* im_context,
 // Initialize keyboard manager.
 static void init_keyboard(FlView* self) {
   FlBinaryMessenger* messenger = fl_engine_get_binary_messenger(self->engine);
-  self->text_input_plugin =
-      fl_text_input_plugin_new(messenger, self, text_input_im_filter_by_gtk);
+  self->text_input_plugin = fl_text_input_plugin_new(
+      messenger, gtk_widget_get_window(GTK_WIDGET(self)),
+      text_input_im_filter_by_gtk);
   self->keyboard_manager =
       fl_keyboard_manager_new(FL_KEYBOARD_VIEW_DELEGATE(self));
 }

shell/platform/linux/testing/mock_binary_messenger.cc

@@ -3,6 +3,7 @@
 // found in the LICENSE file.
 
 #include "flutter/shell/platform/linux/testing/mock_binary_messenger.h"
+#include "flutter/shell/platform/linux/testing/mock_binary_messenger_response_handle.h"
 
 using namespace flutter::testing;
 
@@ -17,6 +18,30 @@ struct _FlMockBinaryMessenger {
   MockBinaryMessenger* mock;
 };
 
+bool MockBinaryMessenger::HasMessageHandler(const gchar* channel) const {
+  return message_handlers.at(channel) != nullptr;
+}
+
+void MockBinaryMessenger::SetMessageHandler(
+    const gchar* channel,
+    FlBinaryMessengerMessageHandler handler,
+    gpointer user_data) {
+  message_handlers[channel] = handler;
+  user_datas[channel] = user_data;
+}
+
+void MockBinaryMessenger::ReceiveMessage(FlBinaryMessenger* messenger,
+                                         const gchar* channel,
+                                         GBytes* message) {
+  FlBinaryMessengerMessageHandler handler = message_handlers[channel];
+  if (response_handles[channel] == nullptr) {
+    response_handles[channel] = FL_BINARY_MESSENGER_RESPONSE_HANDLE(
+        fl_mock_binary_messenger_response_handle_new());
+  }
+  handler(messenger, channel, message, response_handles[channel],
+          user_datas[channel]);
+}
+
 static void fl_mock_binary_messenger_iface_init(
     FlBinaryMessengerInterface* iface);
 
@@ -38,6 +63,7 @@ static void fl_mock_binary_messenger_set_message_handler_on_channel(
     GDestroyNotify destroy_notify) {
   g_return_if_fail(FL_IS_MOCK_BINARY_MESSENGER(messenger));
   FlMockBinaryMessenger* self = FL_MOCK_BINARY_MESSENGER(messenger);
+  self->mock->SetMessageHandler(channel, handler, user_data);
   self->mock->fl_binary_messenger_set_message_handler_on_channel(
       messenger, channel, handler, user_data, destroy_notify);
 }

shell/platform/linux/testing/mock_binary_messenger.h

@@ -5,6 +5,8 @@
 #ifndef FLUTTER_SHELL_PLATFORM_LINUX_TESTING_MOCK_BINARY_MESSENGER_H_
 #define FLUTTER_SHELL_PLATFORM_LINUX_TESTING_MOCK_BINARY_MESSENGER_H_
 
+#include <unordered_map>
+
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_binary_messenger.h"
 
 #include "gmock/gmock.h"
@@ -40,6 +42,23 @@ class MockBinaryMessenger {
                GBytes*(FlBinaryMessenger* messenger,
                        GAsyncResult* result,
                        GError** error));
+
+  bool HasMessageHandler(const gchar* channel) const;
+
+  void SetMessageHandler(const gchar* channel,
+                         FlBinaryMessengerMessageHandler handler,
+                         gpointer user_data);
+
+  void ReceiveMessage(FlBinaryMessenger* messenger,
+                      const gchar* channel,
+                      GBytes* message);
+
+ private:
+  std::unordered_map<std::string, FlBinaryMessengerMessageHandler>
+      message_handlers;
+  std::unordered_map<std::string, FlBinaryMessengerResponseHandle*>
+      response_handles;
+  std::unordered_map<std::string, gpointer> user_datas;
 };
 
 }  // namespace testing