chore: add GUT test framework

addons/gut/test/unit/test_bugs/test_i578.gd

@@ -0,0 +1,105 @@
+extends GutTest
+
+class InputSingletonTracker:
+	extends Node
+	var pressed_frames = []
+	var just_pressed_count = 0
+	var just_released_count = 0
+
+	var _frame_counter = 0
+
+	func _process(_delta):
+		_frame_counter += 1
+
+		if(Input.is_action_just_pressed("jump")):
+			just_pressed_count += 1
+
+		if(Input.is_action_just_released("jump")):
+			just_released_count += 1
+
+		if Input.is_action_pressed("jump"):
+			pressed_frames.append(_frame_counter)
+
+
+
+# ------------------------------------------------------------------------------
+# There are a few tests in here that will fail if the window changes to
+# a different monitor at any point before these tests are run.  I was able to
+# replicate the issue consistently.
+#
+# Fails when (MacOS)
+# * Drag the window to a different monitor.
+# * Use keystroke (better-snap-tools) to move window.
+# * Window is dragged and "held" on another monitor.
+#
+# Passes when (MacOS)
+# * The window is not moved.
+# * Window is moved around on the same monitor.
+# * The window is being "held" on the original monitor.
+# * Window is moved back to original monitor before these tests are executed.
+#   This appears to be the case regardless of the number of times the window
+#   changes monitor.
+#
+# To test these scenarios I used the following to run a script that just delays
+# for a bit, and then run this script.
+# gdscript addons/gut/gut_cmdln.gd -gexit -gconfig= -gtest test/resources/wait_awhile.gd,test/unit/test_bugs/test_i578.gd
+# ------------------------------------------------------------------------------
+class TestInputSingleton:
+	extends "res://addons/gut/test.gd"
+	var _sender = InputSender.new(Input)
+
+	func before_all():
+		_sender.release_all()
+		_sender.clear()
+		await wait_physics_frames(10)
+		InputMap.add_action("jump")
+
+
+	func after_all():
+		InputMap.erase_action("jump")
+
+
+	func after_each():
+		_sender.release_all()
+		# Wait for key release to be processed. Otherwise the key release is
+		# leaked to the next test and it detects an extra key release.
+		await wait_physics_frames(1)
+		_sender.clear()
+
+
+	func test_raw_input_press():
+		var r = add_child_autofree(InputSingletonTracker.new())
+
+		Input.action_press("jump")
+		await wait_physics_frames(2)
+		Input.action_release("jump")
+
+		# see inner-test-class note
+		assert_gt(r.pressed_frames.size(), 1, 'input size (FAILS if window changes monitor)')
+
+	func test_input_sender_press():
+		var r = add_child_autofree(InputSingletonTracker.new())
+
+		_sender.action_down("jump").hold_for('10f')
+		await wait_for_signal(_sender.idle, 5)
+
+		assert_gt(r.pressed_frames.size(), 1, 'input size')
+
+	func test_input_sender_just_pressed():
+		var r = add_child_autofree(InputSingletonTracker.new())
+
+		_sender.action_down("jump").hold_for("20f")
+		await wait_physics_frames(5)
+
+		assert_eq(r.just_pressed_count, 1, 'just pressed once')
+		assert_eq(r.just_released_count, 0, 'not released yet')
+
+	func test_input_sender_just_released():
+		var r = add_child_autofree(InputSingletonTracker.new())
+
+		_sender.action_down("jump").hold_for('5f')
+		await wait_for_signal(_sender.idle, 10)
+
+		assert_eq(r.just_pressed_count, 1, 'just pressed once')
+		# see inner-test-class note
+		assert_eq(r.just_released_count, 1, 'released key once (FAILS if window changes monitor)')