Make a mock messenger that can easily mock channels (#56867)

The previous mock required knowing the specific functions used in the
binary messenger, this method instead allows test code to provide
complete platform channel implementation for testing and make simulated
platform channel calls into embedder code.

Author: robert-ancell

shell/platform/linux/BUILD.gn

@@ -249,11 +249,10 @@ executable("flutter_linux_unittests") {
     "fl_view_test.cc",
     "fl_window_state_monitor_test.cc",
     "key_mapping_test.cc",
+    "testing/fl_mock_binary_messenger.cc",
     "testing/fl_test.cc",
     "testing/fl_test_gtk_logs.cc",
     "testing/fl_test_gtk_logs.h",
-    "testing/mock_binary_messenger.cc",
-    "testing/mock_binary_messenger_response_handle.cc",
     "testing/mock_engine.cc",
     "testing/mock_epoxy.cc",
     "testing/mock_im_context.cc",

shell/platform/linux/fl_binary_messenger_test.cc

@@ -16,9 +16,34 @@
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_method_channel.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_standard_method_codec.h"
 #include "flutter/shell/platform/linux/testing/fl_test.h"
-#include "flutter/shell/platform/linux/testing/mock_binary_messenger_response_handle.h"
 #include "flutter/shell/platform/linux/testing/mock_renderer.h"
 
+G_DECLARE_FINAL_TYPE(FlFakeBinaryMessengerResponseHandle,
+                     fl_fake_binary_messenger_response_handle,
+                     FL,
+                     FAKE_BINARY_MESSENGER_RESPONSE_HANDLE,
+                     FlBinaryMessengerResponseHandle)
+
+struct _FlFakeBinaryMessengerResponseHandle {
+  FlBinaryMessengerResponseHandle parent_instance;
+};
+
+G_DEFINE_TYPE(FlFakeBinaryMessengerResponseHandle,
+              fl_fake_binary_messenger_response_handle,
+              fl_binary_messenger_response_handle_get_type());
+
+static void fl_fake_binary_messenger_response_handle_class_init(
+    FlFakeBinaryMessengerResponseHandleClass* klass) {}
+
+static void fl_fake_binary_messenger_response_handle_init(
+    FlFakeBinaryMessengerResponseHandle* self) {}
+
+FlFakeBinaryMessengerResponseHandle*
+fl_fake_binary_messenger_response_handle_new() {
+  return FL_FAKE_BINARY_MESSENGER_RESPONSE_HANDLE(
+      g_object_new(fl_fake_binary_messenger_response_handle_get_type(), NULL));
+}
+
 G_DECLARE_FINAL_TYPE(FlFakeBinaryMessenger,
                      fl_fake_binary_messenger,
                      FL,
@@ -55,7 +80,7 @@ static gboolean send_message_cb(gpointer user_data) {
   g_autoptr(GBytes) message = g_bytes_new(text, strlen(text));
   self->message_handler(FL_BINARY_MESSENGER(self), "CHANNEL", message,
                         FL_BINARY_MESSENGER_RESPONSE_HANDLE(
-                            fl_mock_binary_messenger_response_handle_new()),
+                            fl_fake_binary_messenger_response_handle_new()),
                         self->message_handler_user_data);
 
   return FALSE;
@@ -83,7 +108,7 @@ static gboolean send_response(FlBinaryMessenger* messenger,
                               GError** error) {
   FlFakeBinaryMessenger* self = FL_FAKE_BINARY_MESSENGER(messenger);
 
-  EXPECT_TRUE(FL_IS_MOCK_BINARY_MESSENGER_RESPONSE_HANDLE(response_handle));
+  EXPECT_TRUE(FL_IS_FAKE_BINARY_MESSENGER_RESPONSE_HANDLE(response_handle));
 
   g_autofree gchar* text =
       g_strndup(static_cast<const gchar*>(g_bytes_get_data(response, nullptr)),

shell/platform/linux/fl_key_channel_responder.cc

@@ -94,8 +94,6 @@ struct _FlKeyChannelResponder {
   GObject parent_instance;
 
   FlBasicMessageChannel* channel;
-
-  FlKeyChannelResponderMock* mock;
 };
 
 G_DEFINE_TYPE(FlKeyChannelResponder, fl_key_channel_responder, G_TYPE_OBJECT)
@@ -117,9 +115,6 @@ static void handle_response(GObject* object,
   FlBasicMessageChannel* messageChannel = FL_BASIC_MESSAGE_CHANNEL(object);
   FlValue* message =
       fl_basic_message_channel_send_finish(messageChannel, result, &error);
-  if (self->mock != nullptr && self->mock->value_converter != nullptr) {
-    message = self->mock->value_converter(message);
-  }
   bool handled = false;
   if (error != nullptr) {
     g_warning("Unable to retrieve framework response: %s", error->message);
@@ -152,22 +147,16 @@ static void fl_key_channel_responder_init(FlKeyChannelResponder* self) {}
 
 // Creates a new FlKeyChannelResponder instance, with a messenger used to send
 // messages to the framework, and an FlTextInputHandler that is used to handle
-// key events that the framework doesn't handle. Mainly for testing purposes, it
-// also takes an optional callback to call when a response is received, and an
-// optional channel name to use when sending messages.
+// key events that the framework doesn't handle.
 FlKeyChannelResponder* fl_key_channel_responder_new(
-    FlBinaryMessenger* messenger,
-    FlKeyChannelResponderMock* mock) {
+    FlBinaryMessenger* messenger) {
   g_return_val_if_fail(FL_IS_BINARY_MESSENGER(messenger), nullptr);
 
   FlKeyChannelResponder* self = FL_KEY_CHANNEL_RESPONDER(
       g_object_new(fl_key_channel_responder_get_type(), nullptr));
-  self->mock = mock;
 
   g_autoptr(FlJsonMessageCodec) codec = fl_json_message_codec_new();
-  const char* channel_name =
-      mock == nullptr ? kChannelName : mock->channel_name;
-  self->channel = fl_basic_message_channel_new(messenger, channel_name,
+  self->channel = fl_basic_message_channel_new(messenger, kChannelName,
                                                FL_MESSAGE_CODEC(codec));
 
   return self;

shell/platform/linux/fl_key_channel_responder.h

@@ -11,27 +11,6 @@
 
 typedef FlValue* (*FlValueConverter)(FlValue*);
 
-/**
- * FlKeyChannelResponderMock:
- *
- * Allows mocking of FlKeyChannelResponder methods and values. Only used in
- * unittests.
- */
-typedef struct _FlKeyChannelResponderMock {
-  /**
-   * FlKeyChannelResponderMock::value_converter:
-   * If #value_converter is not nullptr, then this function is applied to the
-   * reply of the message, whose return value is taken as the message reply.
-   */
-  FlValueConverter value_converter;
-
-  /**
-   * FlKeyChannelResponderMock::channel_name:
-   * Mocks the channel name to send the message.
-   */
-  const char* channel_name;
-} FlKeyChannelResponderMock;
-
 G_BEGIN_DECLS
 
 G_DECLARE_FINAL_TYPE(FlKeyChannelResponder,
@@ -64,15 +43,13 @@ typedef void (*FlKeyChannelResponderAsyncCallback)(bool handled,
 /**
  * fl_key_channel_responder_new:
  * @messenger: the messenger that the message channel should be built on.
- * @mock: options to mock several functionalities. Only used in unittests.
  *
  * Creates a new #FlKeyChannelResponder.
  *
  * Returns: a new #FlKeyChannelResponder.
  */
 FlKeyChannelResponder* fl_key_channel_responder_new(
-    FlBinaryMessenger* messenger,
-    FlKeyChannelResponderMock* mock = nullptr);
+    FlBinaryMessenger* messenger);
 
 /**
  * fl_key_channel_responder_handle_event: