fix(scan_control): preserve configured default scan and label filter button

bec_widgets/widgets/control/scan_control/scan_control.py

@@ -93,7 +93,8 @@ class ScanControl(BECWidget, QWidget):
         self.previous_scan = None
 
         # Widget Default Parameters
-        self.config.default_scan = default_scan
+        if default_scan is not None:
+            self.config.default_scan = default_scan
         if allowed_scans is not None:
             self.config.allowed_scans = allowed_scans
 
@@ -140,6 +141,7 @@ class ScanControl(BECWidget, QWidget):
             material_icon("filter_list", size=(20, 20), convert_to_pixmap=False)
         )
         self.scan_selector_settings_button.setToolTip("Choose scans shown in the selector")
+        self.scan_selector_settings_button.setAccessibleName("Scan selector settings")
         scan_selection_layout.addWidget(self.comboBox_scan_selection_label, 0)
         scan_selection_layout.addWidget(self.comboBox_scan_selection, 1)
         scan_selection_layout.addWidget(self.scan_info_button, 0)
@@ -170,10 +172,6 @@ class ScanControl(BECWidget, QWidget):
         self.button_layout.addWidget(self.button_stop_scan)
         self.layout.addWidget(self.scan_control_group)
 
-        # Default scan from config
-        if self.config.default_scan is not None:
-            self.comboBox_scan_selection.setCurrentText(self.config.default_scan)
-
         # Connect signals
         self.comboBox_scan_selection.view().pressed.connect(self.save_current_scan_parameters)
         self.comboBox_scan_selection.currentIndexChanged.connect(self.on_scan_selection_changed)
@@ -186,6 +184,10 @@ class ScanControl(BECWidget, QWidget):
         # Initialize scan selection
         self.populate_scans()
 
+        # Default scan from config; applied after population so the entry exists
+        if self.config.default_scan is not None:
+            self.comboBox_scan_selection.setCurrentText(self.config.default_scan)
+
         # Append metadata form
         self._add_metadata_form()
 

tests/unit_tests/test_scan_control.py

@@ -411,6 +411,23 @@ def test_configured_allowed_scans_are_preserved(qtbot, mocked_client):
     assert widget.comboBox_scan_selection.currentText() == "grid_scan"
 
 
+def test_configured_default_scan_is_preserved_and_applied(qtbot, mocked_client):
+    mocked_client.connector.set_and_publish(
+        MessageEndpoints.available_scans(), available_scans_message
+    )
+
+    widget = ScanControl(client=mocked_client, default_scan="grid_scan")
+    qtbot.addWidget(widget)
+    assert widget.comboBox_scan_selection.currentText() == "grid_scan"
+
+    # A default_scan from a passed-in config must not be wiped by the ctor default None
+    config = ScanControlConfig(widget_class="ScanControl", default_scan="grid_scan")
+    widget_from_config = ScanControl(client=mocked_client, config=config)
+    qtbot.addWidget(widget_from_config)
+    assert widget_from_config.config.default_scan == "grid_scan"
+    assert widget_from_config.comboBox_scan_selection.currentText() == "grid_scan"
+
+
 def test_scan_selector_settings_dialog_applies_checked_scans(scan_control, monkeypatch, qtbot):
     def select_line_scan(dialog):
         labels = [dialog.checkbox_for_scan(name).text() for name in ("line_scan", "grid_scan")]