Add exam-style question calculator

tests/calculator_panel_test.gd

@@ -0,0 +1,126 @@
+extends SceneTree
+
+var failures := 0
+
+
+func _initialize() -> void:
+	call_deferred("_run")
+
+
+func _run() -> void:
+	_test_basic_arithmetic()
+	_test_decimal_and_chained_operations()
+	_test_percent_and_sign()
+	_test_square_root()
+	_test_repeated_equals()
+	_test_backspace_and_clear()
+	_test_error_recovery()
+	await _test_runtime_panel_behavior()
+	quit(1 if failures > 0 else 0)
+
+
+func _calculator():
+	return load("res://scripts/ui/calculator_panel.gd").new()
+
+
+func _press(calculator, tokens: Array) -> void:
+	for token in tokens:
+		calculator.press_token(str(token))
+
+
+func _test_basic_arithmetic() -> void:
+	var calculator = _calculator()
+	_press(calculator, ["9", "+", "6", "="])
+	_assert(calculator.get_display_text() == "15", "calculator should add operands")
+	calculator.reset_calculation()
+	_press(calculator, ["9", "−", "4", "="])
+	_assert(calculator.get_display_text() == "5", "calculator should subtract operands")
+	calculator.reset_calculation()
+	_press(calculator, ["7", "×", "8", "="])
+	_assert(calculator.get_display_text() == "56", "calculator should multiply operands")
+	calculator.reset_calculation()
+	_press(calculator, ["8", "÷", "4", "="])
+	_assert(calculator.get_display_text() == "2", "calculator should divide operands")
+	calculator.free()
+
+
+func _test_decimal_and_chained_operations() -> void:
+	var calculator = _calculator()
+	_press(calculator, ["1", ".", "5", "+", "2", ".", "5", "×", "2", "="])
+	_assert(calculator.get_display_text() == "8", "calculator should evaluate chained handheld operations left to right")
+	calculator.free()
+
+
+func _test_percent_and_sign() -> void:
+	var calculator = _calculator()
+	_press(calculator, ["5", "%"])
+	_assert(calculator.get_display_text() == "0.05", "percent should convert the displayed operand to a fraction")
+	_press(calculator, ["±"])
+	_assert(calculator.get_display_text() == "-0.05", "sign toggle should negate the displayed operand")
+	calculator.free()
+
+
+func _test_square_root() -> void:
+	var calculator = _calculator()
+	_press(calculator, ["8", "1", "√"])
+	_assert(calculator.get_display_text() == "9", "square root should replace the displayed operand")
+	calculator.free()
+
+
+func _test_repeated_equals() -> void:
+	var calculator = _calculator()
+	_press(calculator, ["5", "+", "2", "=", "="])
+	_assert(calculator.get_display_text() == "9", "repeated equals should replay the last binary operation")
+	calculator.free()
+
+
+func _test_backspace_and_clear() -> void:
+	var calculator = _calculator()
+	_press(calculator, ["1", "2", "3", "⌫"])
+	_assert(calculator.get_display_text() == "12", "backspace should remove the final entry digit")
+	_press(calculator, ["AC"])
+	_assert(calculator.get_display_text() == "0", "clear should reset the display")
+	calculator.free()
+
+
+func _test_error_recovery() -> void:
+	var calculator = _calculator()
+	_press(calculator, ["8", "÷", "0", "="])
+	_assert(calculator.get_display_text() == "Error", "division by zero should display an error")
+	_press(calculator, ["4"])
+	_assert(calculator.get_display_text() == "4", "digit entry should recover from an error")
+	_press(calculator, ["±", "√"])
+	_assert(calculator.get_display_text() == "Error", "square root of a negative operand should display an error")
+	calculator.free()
+
+
+func _test_runtime_panel_behavior() -> void:
+	var host := Control.new()
+	host.size = Vector2(360, 640)
+	root.add_child(host)
+	var calculator = _calculator()
+	host.add_child(calculator)
+	await process_frame
+	calculator.open_panel()
+	await process_frame
+	_assert(calculator.visible, "calculator should open as a floating panel")
+	_assert(calculator.size.x <= 336.0, "calculator should fit a narrow web viewport")
+	_press(calculator, ["2", "+", "3", "="])
+	calculator.close_panel()
+	calculator.open_panel()
+	_assert(calculator.get_display_text() == "5", "closing and reopening should preserve the active-session value")
+	calculator.position = Vector2(1000, 1000)
+	calculator._clamp_to_viewport()
+	_assert(calculator.position.x + calculator.size.x <= calculator.get_viewport_rect().size.x, "calculator dragging should remain horizontally bounded")
+	_assert(calculator.position.y + calculator.size.y <= calculator.get_viewport_rect().size.y, "calculator dragging should remain vertically bounded")
+	calculator.reset_calculation()
+	_assert(calculator.get_display_text() == "0", "session reset should clear calculator state")
+	host.queue_free()
+	await process_frame
+
+
+func _assert(condition: bool, message: String) -> void:
+	if condition:
+		return
+	failures += 1
+	push_error(message)