GD-598: Fixing memory leaks on test execution (#599)

# Why
Running tests via CMD line shows a lot of memory leaks at program exit.

# What
- fixed releasing of all singletons
- `func_assert` has problems with lambdas when using inside
`timer.timeout.connect`, converted lambda into function
- Handling of stored asserts in the thread context results in
inconsistency during cleanup
- fixed cleanup on `GdUnitCommandHandlerTest`


## Finally, I have reduced most of the memory leaks nodes, but there are
still `GDScriptFunctionState` orphaned nodes that I can't solve because
these are handled internally by Godot see
[74449](godotengine/godot#74449)

```
Statistics: | 947 tests cases | 0 error | 0 failed | 1 flaky | 13 skipped | 0 orphans |

Executed test suites: (100/104), 4 skipped
Executed test cases: (934/947), 13 skipped
Total time:        3min 0s 409ms
Open Report at: file:///home/runner/work/gdUnit4/gdUnit4/reports/report_1/index.html
Exit code: 0
----------------------------------------------------------------
Cleanup singletons ["GdUnitThreadManager", "GdUnitDefaultValueDecoders", "GdUnitCommandHandler"]

	Unregister singleton 'GdUnitThreadManager'
	Free singleton instance 'GdUnitThreadManager:<Object#507678557642>'
	Successfully freed 'GdUnitThreadManager'

	Unregister singleton 'GdUnitDefaultValueDecoders'
	Free singleton instance 'GdUnitDefaultValueDecoders:<Object#509540832395>'
	Successfully freed 'GdUnitDefaultValueDecoders'

	Unregister singleton 'GdUnitCommandHandler'
	Free singleton instance 'GdUnitCommandHandler:<Object#3858659025580>'
	Successfully freed 'GdUnitCommandHandler'
----------------------------------------------------------------
Finallize .. done
Finallize ..
-Orphan nodes report-----------------------
Finallize .. done
XR: Clearing primary interface
XR: Removed interface "Native mobile"
XR: Removed interface "OpenXR"
WARNING: ObjectDB instances leaked at exit (run with --verbose for details).
     at: cleanup (core/object/object.cpp:2327)
Leaked instance: GDScriptFunctionState:9223373291404658414
Leaked instance: GDScriptFunctionState:92233732947[6010](https://github.com/MikeSchulze/gdUnit4/actions/runs/11956449331/job/33331231410?pr=599#step:4:6018)1646
Leaked instance: GDScriptFunctionState:9223373292545509197
Leaked instance: GDScriptFunctionState:9223373291673093970
Leaked instance: GDScriptFunctionState:9223373293719914330
Leaked instance: GDScriptFunctionState:9223373292881053539
Leaked instance: GDScriptFunctionState:9223373296521709422
Leaked instance: GDScriptFunctionState:9223378085393468557
Leaked instance: GDScriptFunctionState:9223382060754801221
Leaked instance: GDScriptFunctionState:9223373293753472331
Leaked instance: GDScriptFunctionState:9223377142497156399
Leaked instance: GDScriptFunctionState:9223378085359924447
Leaked instance: GDScriptFunctionState:9223382060788375283
Hint: Leaked instances typically happen when nodes are removed from the scene tree (with `remove_child()`) but not freed (with `free()` or `queue_free()`).
Orphan StringName: test_case1 (static: 0, total: 1)
Orphan StringName: _validate_callback (static: 0, total: 1)
Orphan StringName: await_millis (static: 0, total: 5)
Orphan StringName: test_timeout_single_yield_wait (static: 0, total: 1)
Orphan StringName: test_timeout_2s (static: 0, total: 1)
Orphan StringName: _execute (static: 0, total: 1)
Orphan StringName: test_timeout_4s (static: 0, total: 1)
Orphan StringName: timeout (static: 2, total: 8)
Orphan StringName: cb_is_equal (static: 0, total: 2)
Orphan StringName: test_timeout_long_running_test_abort (static: 0, total: 1)
Orphan StringName: test_timeout_and_assert_fails (static: 0, total: 1)
StringName: 11 unclaimed string names at exit.
Run tests ends with 0
```

.github/workflows/ci-pr.yml

@@ -66,6 +66,8 @@ jobs:
           version: installed
           paths: |
             res://addons/gdUnit4/test/
+          arguments: |
+            --verbose
           timeout: 10
           publish-report: false
           report-name: gdUnit4_Godot${{ matrix.godot-version }}-${{ matrix.godot-status }}

addons/gdUnit4/src/asserts/GdUnitFuncAssertImpl.gd

@@ -29,15 +29,19 @@ func _init(instance :Object, func_name :String, args := Array()) -> void:
 		_current_value_provider = CallBackValueProvider.new(instance, func_name, args)
 
 
-func _notification(_what :int) -> void:
-	if is_instance_valid(_current_value_provider):
-		_current_value_provider.dispose()
-		_current_value_provider = null
-	if is_instance_valid(_sleep_timer):
-		(Engine.get_main_loop() as SceneTree).root.remove_child(_sleep_timer)
-		_sleep_timer.stop()
-		_sleep_timer.free()
-		_sleep_timer = null
+func _notification(what :int) -> void:
+	if what == NOTIFICATION_PREDELETE:
+		_interrupted = true
+		var main_node :Node = (Engine.get_main_loop() as SceneTree).root
+		if is_instance_valid(_current_value_provider):
+			_current_value_provider.dispose()
+			_current_value_provider = null
+		if is_instance_valid(_sleep_timer):
+			_sleep_timer.set_wait_time(0.0001)
+			_sleep_timer.stop()
+			main_node.remove_child(_sleep_timer)
+			_sleep_timer.free()
+			_sleep_timer = null
 
 
 func report_success() -> GdUnitFuncAssert:
@@ -114,6 +118,10 @@ func cb_is_equal(c :Variant, e :Variant) -> bool: return GdObjects.equals(c,e)
 func cb_is_not_equal(c :Variant, e :Variant) -> bool: return not GdObjects.equals(c, e)
 
 
+func do_interrupt() -> void:
+	_interrupted = true
+
+
 func _validate_callback(predicate :Callable, expected :Variant = null) -> void:
 	if _interrupted:
 		return
@@ -125,9 +133,7 @@ func _validate_callback(predicate :Callable, expected :Variant = null) -> void:
 	scene_tree.root.add_child(timer)
 	timer.add_to_group("GdUnitTimers")
 	@warning_ignore("return_value_discarded")
-	timer.timeout.connect(func do_interrupt() -> void:
-		_interrupted = true
-		, CONNECT_DEFERRED)
+	timer.timeout.connect(do_interrupt, CONNECT_DEFERRED)
 	timer.set_one_shot(true)
 	timer.start((_timeout/1000.0)*time_scale)
 	_sleep_timer = Timer.new()

addons/gdUnit4/src/asserts/GdUnitSignalAssertImpl.gd

@@ -22,6 +22,14 @@ func _init(emitter :Object) -> void:
 	GdAssertReports.reset_last_error_line_number()
 
 
+func _notification(what :int) -> void:
+	if what == NOTIFICATION_PREDELETE:
+		_interrupted = true
+		if is_instance_valid(_emitter):
+			_signal_collector.unregister_emitter(_emitter)
+		_emitter = null
+
+
 func report_success() -> GdUnitAssert:
 	GdAssertReports.report_success()
 	return self

addons/gdUnit4/src/core/GdUnitSingleton.gd

@@ -47,10 +47,10 @@ static func unregister(p_singleton :String, use_call_deferred :bool = false) ->
 
 static func dispose(use_call_deferred :bool = false) -> void:
 	# use a copy because unregister is modify the singletons array
-	var singletons: PackedStringArray = Engine.get_meta(MEATA_KEY, PackedStringArray())
+	var singletons :PackedStringArray = Engine.get_meta(MEATA_KEY, PackedStringArray())
 	GdUnitTools.prints_verbose("----------------------------------------------------------------")
 	GdUnitTools.prints_verbose("Cleanup singletons %s" % singletons)
-	for singleton in singletons:
+	for singleton in PackedStringArray(singletons):
 		unregister(singleton, use_call_deferred)
 	Engine.remove_meta(MEATA_KEY)
 	GdUnitTools.prints_verbose("----------------------------------------------------------------")

addons/gdUnit4/src/core/execution/GdUnitExecutionContext.gd

@@ -348,5 +348,7 @@ func register_auto_free(obj: Variant) -> Variant:
 
 ## Runs the gdunit garbage collector to free registered object
 func gc() -> void:
+	# unreference last used assert form the test to prevent memory leaks
+	GdUnitThreadManager.get_current_context().clear_assert()
 	await _memory_observer.gc()
 	orphan_monitor_stop()

addons/gdUnit4/src/core/execution/stages/GdUnitTestCaseAfterStage.gd

@@ -17,8 +17,7 @@ func _execute(context: GdUnitExecutionContext) -> void:
 	if _call_stage:
 		@warning_ignore("redundant_await")
 		await test_suite.after_test()
-	# unreference last used assert form the test to prevent memory leaks
-	GdUnitThreadManager.get_current_context().set_assert(null)
+
 	await context.gc()
 	await context.error_monitor_stop()
 

addons/gdUnit4/src/core/execution/stages/GdUnitTestSuiteAfterStage.gd

@@ -12,8 +12,6 @@ func _execute(context :GdUnitExecutionContext) -> void:
 
 	@warning_ignore("redundant_await")
 	await test_suite.after()
-	# unreference last used assert form the test to prevent memory leaks
-	GdUnitThreadManager.get_current_context().set_assert(null)
 	await context.gc()
 	var reports := context.build_reports(false)
 	fire_event(GdUnitEvent.new()\

addons/gdUnit4/src/core/thread/GdUnitThreadContext.gd

@@ -4,9 +4,9 @@ extends RefCounted
 var _thread :Thread
 var _thread_name :String
 var _thread_id :int
-var _assert :GdUnitAssert
 var _signal_collector :GdUnitSignalCollector
 var _execution_context :GdUnitExecutionContext
+var _asserts := []
 
 
 func _init(thread :Thread = null) -> void:
@@ -21,20 +21,25 @@ func _init(thread :Thread = null) -> void:
 
 
 func dispose() -> void:
-	_assert = null
+	clear_assert()
 	if is_instance_valid(_signal_collector):
 		_signal_collector.clear()
 	_signal_collector = null
 	_execution_context = null
 	_thread = null
 
 
+func clear_assert() -> void:
+	_asserts.clear()
+
+
 func set_assert(value :GdUnitAssert) -> void:
-	_assert = value
+	if value != null:
+		_asserts.append(value)
 
 
 func get_assert() -> GdUnitAssert:
-	return _assert
+	return null if _asserts.is_empty() else _asserts[-1]
 
 
 func set_execution_context(context :GdUnitExecutionContext) -> void:

addons/gdUnit4/test/core/command/GdUnitCommandHandlerTest.gd

@@ -15,8 +15,7 @@ func before() -> void:
 
 
 func after() -> void:
-	_handler._notification(NOTIFICATION_PREDELETE)
-	_handler = null
+	_handler.free()
 
 
 @warning_ignore('unused_parameter')