test: add device controller test

tests/test_device_controller.py

@@ -140,3 +140,50 @@ def test_logging_handler(controller):
     logger = logging.getLogger("test_logger")
     logger.info("Hello QML Activity Log")
     assert any("Hello QML Activity Log" in line for line in controller._activity_log)
+
+def test_fresh_session_on_startup(mock_settings):
+    import tempfile
+    import shutil
+    
+    # Configure mock settings with some data to simulate previous session
+    mock_settings.activity_log = ["[12:00:00] Old message"]
+    mock_settings.selected_port = "COM9"
+    mock_settings.last_wafer_info = {"familyCode": "P", "serialNumber": "P00002"}
+    mock_settings.data_row_count = 50
+    mock_settings.data_col_count = 244
+    
+    temp_dir = tempfile.mkdtemp()
+    try:
+        new_controller = DeviceController(mock_settings, temp_dir)
+        # Should start completely fresh (empty/default) ignoring the persisted status
+        assert len(new_controller._activity_log) == 0
+        assert new_controller.selectedPort == ""
+        assert new_controller.lastWaferInfo == ["", "", 0, "", 0, 0]
+        assert new_controller.dataRowCount == 0
+        assert new_controller.dataColCount == 0
+    finally:
+        shutil.rmtree(temp_dir)
+
+def test_detect_wafer_clears_old_session(controller):
+    controller._selected_port = "COM1"
+    controller._last_wafer_info = {"familyCode": "P", "serialNumber": "P00001"}
+    controller._data_row_count = 10
+    controller._data_col_count = 244
+    controller._activity_log.append("[12:00:00] Previous message")
+    
+    # We mock detect_all_ports to not run long or fail
+    controller._service.detect_all_ports = MagicMock(return_value=(None, None))
+    
+    with patch("threading.Thread") as mock_thread:
+        controller.detectWafer()
+        
+        # Verify it cleared all session variables and logs immediately at start of detect
+        assert controller.selectedPort == ""
+        assert controller.lastWaferInfo == ["", "", 0, "", 0, 0]
+        assert controller.dataRowCount == 0
+        assert controller.dataColCount == 0
+        
+        # Log should only contain "Scanning all ports for wafer ..."
+        assert len(controller._activity_log) == 1
+        assert "Scanning all ports" in controller._activity_log[0]
+