fix(lmfit_dialog): fix fit_curve_id type annotation and remove_dap_data selection behavior

Co-authored-by: wyzula-jan <133381102+wyzula-jan@users.noreply.github.com>
Agent-Logs-Url: https://github.com/bec-project/bec_widgets/sessions/97395c0e-0271-4cdf-b39f-f3117d21bfa3

bec_widgets/widgets/dap/lmfit_dialog/lmfit_dialog.py

@@ -80,7 +80,8 @@ class LMFitDialog(BECWidget, QWidget):
         self._enable_actions = enable
         valid_buttons = {}
         for name, button in self.action_buttons.items():
-            if button is None or not shiboken6.isValid(button):  # to fix cpp object deleted
+            # just to be sure we have a valid c++ object
+            if button is None or not shiboken6.isValid(button):
                 continue
             button.setEnabled(enable)
             valid_buttons[name] = button
@@ -150,19 +151,21 @@ class LMFitDialog(BECWidget, QWidget):
         self.ui.group_parameters.setVisible(not show)
 
     @property
-    def fit_curve_id(self) -> str:
+    def fit_curve_id(self) -> str | None:
         """SafeProperty for the currently displayed fit curve_id."""
         return self._fit_curve_id
 
     @fit_curve_id.setter
-    def fit_curve_id(self, curve_id: str):
+    def fit_curve_id(self, curve_id: str | None):
         """Setter for the currently displayed fit curve_id.
 
         Args:
-            curve_id (str): The curve_id of the fit curve to be displayed.
+            curve_id (str | None): The curve_id of the fit curve to be displayed,
+                or None to clear the selection.
         """
         self._fit_curve_id = curve_id
-        self.selected_fit.emit(curve_id)
+        if curve_id is not None:
+            self.selected_fit.emit(curve_id)
 
     @SafeSlot(str)
     def remove_dap_data(self, curve_id: str):
@@ -173,10 +176,14 @@ class LMFitDialog(BECWidget, QWidget):
         """
         self.summary_data.pop(curve_id, None)
         if self.fit_curve_id == curve_id:
-            self._fit_curve_id = None
             self.action_buttons = {}
             self.ui.summary_tree.clear()
             self.ui.param_tree.clear()
+            remaining = list(self.summary_data.keys())
+            if remaining:
+                self.fit_curve_id = remaining[0]
+            else:
+                self._fit_curve_id = None
         self.refresh_curve_list()
 
     @SafeSlot(str)

tests/unit_tests/test_lmfit_dialog.py

@@ -140,7 +140,7 @@ def lmfit_message():
 
 
 def test_fit_curve_id(lmfit_dialog):
-    """Test hide_curve_selection property"""
+    """Test fit_curve_id property and selected_fit signal"""
     my_callback = mock.MagicMock()
     lmfit_dialog.selected_fit.connect(my_callback)
     assert lmfit_dialog.fit_curve_id is None
@@ -148,6 +148,10 @@ def test_fit_curve_id(lmfit_dialog):
     assert lmfit_dialog.fit_curve_id == "test_curve_id"
     assert my_callback.call_count == 1
     assert my_callback.call_args == mock.call("test_curve_id")
+    # Setting to None should not emit selected_fit
+    lmfit_dialog.fit_curve_id = None
+    assert lmfit_dialog.fit_curve_id is None
+    assert my_callback.call_count == 1
 
 
 def test_remove_dap_data(lmfit_dialog):
@@ -166,6 +170,35 @@ def test_remove_dap_data(lmfit_dialog):
     assert lmfit_dialog.ui.curve_list.count() == 1
 
 
+def test_remove_dap_data_selected_curve_switches_to_next(lmfit_dialog):
+    """Removing the currently selected curve should switch to the next available one"""
+    my_callback = mock.MagicMock()
+    lmfit_dialog.selected_fit.connect(my_callback)
+    lmfit_dialog.summary_data = {"curve_a": "data_a", "curve_b": "data_b"}
+    lmfit_dialog.fit_curve_id = "curve_a"
+    my_callback.reset_mock()
+
+    lmfit_dialog.remove_dap_data("curve_a")
+
+    assert lmfit_dialog.fit_curve_id == "curve_b"
+    assert my_callback.call_count == 1
+    assert my_callback.call_args == mock.call("curve_b")
+
+
+def test_remove_dap_data_selected_curve_clears_when_last(lmfit_dialog):
+    """Removing the only/last selected curve should clear the selection without emitting"""
+    my_callback = mock.MagicMock()
+    lmfit_dialog.selected_fit.connect(my_callback)
+    lmfit_dialog.summary_data = {"curve_a": "data_a"}
+    lmfit_dialog.fit_curve_id = "curve_a"
+    my_callback.reset_mock()
+
+    lmfit_dialog.remove_dap_data("curve_a")
+
+    assert lmfit_dialog.fit_curve_id is None
+    assert my_callback.call_count == 0
+
+
 def test_update_summary_tree(lmfit_dialog, lmfit_message):
     """Test display_fit_details method"""
     lmfit_dialog.active_action_list = ["center", "amplitude"]