[unittests] Send Mouse events via DisplayServer instead of push_input

Currently Unittests simplify mouse-events by just pushing them to Viewports.
For dealing with mouse-screen-coordinates (caused by the introduction of
multiple native Windows) it becomes necessary to extend the
DisplayServer functionality for unittests.

This PR introduces DisplayServerMock based on DisplayServerHeadless,
which additionally supports basic Mouse-Input handling.

4 files changed, 165 insertions, 7 deletions

diff --git a/tests/display_server_mock.h b/tests/display_server_mock.h
new file mode 100644
index 0000000000..1736f2c452
--- /dev/null
+++ b/tests/display_server_mock.h
@@ -0,0 +1,150 @@
+/**************************************************************************/
+/*  display_server_mock.h                                                 */
+/**************************************************************************/
+/*                         This file is part of:                          */
+/*                             GODOT ENGINE                               */
+/*                        https://godotengine.org                         */
+/**************************************************************************/
+/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
+/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
+/*                                                                        */
+/* Permission is hereby granted, free of charge, to any person obtaining  */
+/* a copy of this software and associated documentation files (the        */
+/* "Software"), to deal in the Software without restriction, including    */
+/* without limitation the rights to use, copy, modify, merge, publish,    */
+/* distribute, sublicense, and/or sell copies of the Software, and to     */
+/* permit persons to whom the Software is furnished to do so, subject to  */
+/* the following conditions:                                              */
+/*                                                                        */
+/* The above copyright notice and this permission notice shall be         */
+/* included in all copies or substantial portions of the Software.        */
+/*                                                                        */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,        */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF     */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY   */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,   */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE      */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
+/**************************************************************************/
+
+#ifndef DISPLAY_SERVER_MOCK_H
+#define DISPLAY_SERVER_MOCK_H
+
+#include "servers/display_server_headless.h"
+
+#include "servers/rendering/dummy/rasterizer_dummy.h"
+
+// Specialized DisplayServer for unittests based on DisplayServerHeadless, that
+// additionally supports rudimentary InputEvent handling and mouse position.
+class DisplayServerMock : public DisplayServerHeadless {
+private:
+	friend class DisplayServer;
+
+	Point2i mouse_position = Point2i(-1, -1); // Outside of Window.
+	bool window_over = false;
+	Callable event_callback;
+	Callable input_event_callback;
+
+	static Vector<String> get_rendering_drivers_func() {
+		Vector<String> drivers;
+		drivers.push_back("dummy");
+		return drivers;
+	}
+
+	static DisplayServer *create_func(const String &p_rendering_driver, DisplayServer::WindowMode p_mode, DisplayServer::VSyncMode p_vsync_mode, uint32_t p_flags, const Vector2i *p_position, const Vector2i &p_resolution, int p_screen, Error &r_error) {
+		r_error = OK;
+		RasterizerDummy::make_current();
+		return memnew(DisplayServerMock());
+	}
+
+	static void _dispatch_input_events(const Ref<InputEvent> &p_event) {
+		static_cast<DisplayServerMock *>(get_singleton())->_dispatch_input_event(p_event);
+	}
+
+	void _dispatch_input_event(const Ref<InputEvent> &p_event) {
+		Variant ev = p_event;
+		Variant *evp = &ev;
+		Variant ret;
+		Callable::CallError ce;
+
+		if (input_event_callback.is_valid()) {
+			input_event_callback.callp((const Variant **)&evp, 1, ret, ce);
+		}
+	}
+
+	void _set_mouse_position(const Point2i &p_position) {
+		if (mouse_position == p_position) {
+			return;
+		}
+		mouse_position = p_position;
+		_set_window_over(Rect2i(Point2i(0, 0), window_get_size()).has_point(p_position));
+	}
+
+	void _set_window_over(bool p_over) {
+		if (p_over == window_over) {
+			return;
+		}
+		window_over = p_over;
+		_send_window_event(p_over ? WINDOW_EVENT_MOUSE_ENTER : WINDOW_EVENT_MOUSE_EXIT);
+	}
+
+	void _send_window_event(WindowEvent p_event) {
+		if (!event_callback.is_null()) {
+			Variant event = int(p_event);
+			Variant *eventp = &event;
+			Variant ret;
+			Callable::CallError ce;
+			event_callback.callp((const Variant **)&eventp, 1, ret, ce);
+		}
+	}
+
+public:
+	bool has_feature(Feature p_feature) const override {
+		switch (p_feature) {
+			case FEATURE_MOUSE:
+				return true;
+			default: {
+			}
+		}
+		return false;
+	}
+
+	String get_name() const override { return "mock"; }
+
+	// You can simulate DisplayServer-events by calling this function.
+	// The events will be deliverd to Godot's Input-system.
+	// Mouse-events (Button & Motion) will additionally update the DisplayServer's mouse position.
+	void simulate_event(Ref<InputEvent> p_event) {
+		Ref<InputEventMouse> me = p_event;
+		if (me.is_valid()) {
+			_set_mouse_position(me->get_position());
+		}
+		Input::get_singleton()->parse_input_event(p_event);
+	}
+
+	virtual Point2i mouse_get_position() const override { return mouse_position; }
+
+	virtual Size2i window_get_size(WindowID p_window = MAIN_WINDOW_ID) const override {
+		return Size2i(1920, 1080);
+	}
+
+	virtual void window_set_window_event_callback(const Callable &p_callable, WindowID p_window = MAIN_WINDOW_ID) override {
+		event_callback = p_callable;
+	}
+
+	virtual void window_set_input_event_callback(const Callable &p_callable, WindowID p_window = MAIN_WINDOW_ID) override {
+		input_event_callback = p_callable;
+	}
+
+	static void register_mock_driver() {
+		register_create_function("mock", create_func, get_rendering_drivers_func);
+	}
+
+	DisplayServerMock() {
+		Input::get_singleton()->set_event_dispatch_function(_dispatch_input_events);
+	}
+	~DisplayServerMock() {}
+};
+
+#endif // DISPLAY_SERVER_MOCK_H
diff --git a/tests/scene/test_text_edit.h b/tests/scene/test_text_edit.h
index 944f9cb9f6..f2663b037d 100644
--- a/tests/scene/test_text_edit.h
+++ b/tests/scene/test_text_edit.h
@@ -3271,6 +3271,7 @@ TEST_CASE("[SceneTree][TextEdit] mouse") {
 
 TEST_CASE("[SceneTree][TextEdit] caret") {
 	TextEdit *text_edit = memnew(TextEdit);
+	text_edit->set_context_menu_enabled(false); // Prohibit sending InputEvents to the context menu.
 	SceneTree::get_singleton()->get_root()->add_child(text_edit);
 
 	text_edit->set_size(Size2(800, 200));
diff --git a/tests/test_macros.h b/tests/test_macros.h
index 3074c1abf5..80a93c8327 100644
--- a/tests/test_macros.h
+++ b/tests/test_macros.h
@@ -31,6 +31,8 @@
 #ifndef TEST_MACROS_H
 #define TEST_MACROS_H
 
+#include "display_server_mock.h"
+
 #include "core/core_globals.h"
 #include "core/input/input_map.h"
 #include "core/object/message_queue.h"
@@ -139,13 +141,15 @@ int register_test_command(String p_command, TestFunc p_function);
 // SEND_GUI_MOUSE_MOTION_EVENT - takes an object, position, mouse mask and modifiers e.g SEND_GUI_MOUSE_MOTION_EVENT(code_edit, Vector2(50, 50), MouseButtonMask::LEFT, KeyModifierMask::META);
 // SEND_GUI_DOUBLE_CLICK - takes an object, position and modifiers. e.g SEND_GUI_DOUBLE_CLICK(code_edit, Vector2(50, 50), KeyModifierMask::META);
 
+#define _SEND_DISPLAYSERVER_EVENT(m_event) ((DisplayServerMock *)(DisplayServer::get_singleton()))->simulate_event(m_event);
+
 #define SEND_GUI_ACTION(m_object, m_action)                                                           \
 	{                                                                                                 \
 		const List<Ref<InputEvent>> *events = InputMap::get_singleton()->action_get_events(m_action); \
 		const List<Ref<InputEvent>>::Element *first_event = events->front();                          \
 		Ref<InputEventKey> event = first_event->get();                                                \
 		event->set_pressed(true);                                                                     \
-		m_object->get_viewport()->push_input(event);                                                  \
+		_SEND_DISPLAYSERVER_EVENT(event);                                                             \
 		MessageQueue::get_singleton()->flush();                                                       \
 	}
 
@@ -153,7 +157,7 @@ int register_test_command(String p_command, TestFunc p_function);
 	{                                                                        \
 		Ref<InputEventKey> event = InputEventKey::create_reference(m_input); \
 		event->set_pressed(true);                                            \
-		m_object->get_viewport()->push_input(event);                         \
+		_SEND_DISPLAYSERVER_EVENT(event);                                    \
 		MessageQueue::get_singleton()->flush();                              \
 	}
 
@@ -176,7 +180,7 @@ int register_test_command(String p_command, TestFunc p_function);
 #define SEND_GUI_MOUSE_BUTTON_EVENT(m_object, m_local_pos, m_input, m_mask, m_modifers) \
 	{                                                                                   \
 		_CREATE_GUI_MOUSE_EVENT(m_object, m_local_pos, m_input, m_mask, m_modifers);    \
-		m_object->get_viewport()->push_input(event);                                    \
+		_SEND_DISPLAYSERVER_EVENT(event);                                               \
 		MessageQueue::get_singleton()->flush();                                         \
 	}
 
@@ -184,7 +188,7 @@ int register_test_command(String p_command, TestFunc p_function);
 	{                                                                                            \
 		_CREATE_GUI_MOUSE_EVENT(m_object, m_local_pos, m_input, m_mask, m_modifers);             \
 		event->set_pressed(false);                                                               \
-		m_object->get_viewport()->push_input(event);                                             \
+		_SEND_DISPLAYSERVER_EVENT(event);                                                        \
 		MessageQueue::get_singleton()->flush();                                                  \
 	}
 
@@ -192,7 +196,7 @@ int register_test_command(String p_command, TestFunc p_function);
 	{                                                                                     \
 		_CREATE_GUI_MOUSE_EVENT(m_object, m_local_pos, MouseButton::LEFT, 0, m_modifers); \
 		event->set_double_click(true);                                                    \
-		m_object->get_viewport()->push_input(event);                                      \
+		_SEND_DISPLAYSERVER_EVENT(event);                                                 \
 		MessageQueue::get_singleton()->flush();                                           \
 	}
 
@@ -207,7 +211,7 @@ int register_test_command(String p_command, TestFunc p_function);
 		event->set_button_mask(m_mask);                                        \
 		event->set_relative(Vector2(10, 10));                                  \
 		_UPDATE_EVENT_MODIFERS(event, m_modifers);                             \
-		m_object->get_viewport()->push_input(event);                           \
+		_SEND_DISPLAYSERVER_EVENT(event);                                      \
 		MessageQueue::get_singleton()->flush();                                \
 		CoreGlobals::print_error_enabled = errors_enabled;                     \
 	}
diff --git a/tests/test_main.cpp b/tests/test_main.cpp
index 8c563f94ac..c6b676a7ba 100644
--- a/tests/test_main.cpp
+++ b/tests/test_main.cpp
@@ -106,6 +106,7 @@
 
 #include "modules/modules_tests.gen.h"
 
+#include "tests/display_server_mock.h"
 #include "tests/test_macros.h"
 
 #include "scene/theme/theme_db.h"
@@ -125,6 +126,7 @@ int test_main(int argc, char *argv[]) {
 		args.push_back(String::utf8(argv[i]));
 	}
 	OS::get_singleton()->set_cmdline("", args, List<String>());
+	DisplayServerMock::register_mock_driver();
 
 	// Run custom test tools.
 	if (test_commands) {
@@ -199,11 +201,12 @@ struct GodotTestCaseListener : public doctest::IReporter {
 			memnew(MessageQueue);
 
 			memnew(Input);
+			Input::get_singleton()->set_use_accumulated_input(false);
 
 			Error err = OK;
 			OS::get_singleton()->set_has_server_feature_callback(nullptr);
 			for (int i = 0; i < DisplayServer::get_create_function_count(); i++) {
-				if (String("headless") == DisplayServer::get_create_function_name(i)) {
+				if (String("mock") == DisplayServer::get_create_function_name(i)) {
 					DisplayServer::create(i, "", DisplayServer::WindowMode::WINDOW_MODE_MINIMIZED, DisplayServer::VSyncMode::VSYNC_ENABLED, 0, nullptr, Vector2i(0, 0), DisplayServer::SCREEN_PRIMARY, err);
 					break;
 				}