Fix duplicate choice names in ipynb Dropdown, add Separator support

- Fix #639
- Note that `_mgui_set_choice()` is not used

src/magicgui/backends/_ipynb/widgets.py

@@ -12,6 +12,7 @@
     ) from e
 
 
+from magicgui.types import Separator
 from magicgui.widgets import protocols
 
 if TYPE_CHECKING:
@@ -219,7 +220,9 @@ def _mgui_get_choices(self) -> tuple[tuple[str, Any]]:
 
     def _mgui_set_choices(self, choices: Iterable[tuple[str, Any]]) -> None:
         """Set available choices."""
-        self._ipywidget.options = choices
+        options = [item for item in choices if item[1] is not Separator]
+        options = list(dict(options).items())  # remove duplicate names, last data used
+        self._ipywidget.options = options
 
     def _mgui_del_choice(self, choice_name: str) -> None:
         """Delete a choice."""
@@ -248,7 +251,7 @@ def _mgui_get_current_choice(self) -> str:
 
     def _mgui_set_choice(self, choice_name: str, data: Any) -> None:
         """Set the data associated with a choice."""
-        self._ipywidget.options = (*self._ipywidget.options, (choice_name, data))
+        pass
 
 
 class _IPySupportsText(protocols.SupportsText):

tests/test_widgets.py

@@ -1067,9 +1067,11 @@ def test_separator_singleton():
     assert sep1 is sep2
 
 
-def test_separator():
+def test_separator(backend: str):
     from magicgui.types import Separator
 
+    use_app(backend)
+
     sep = [[Separator] * (i + 1) for i in range(4)]
     a = [1, 2, *sep[0], 4, *sep[1], 6, 7, *sep[2], 9, *sep[3], 11, 12, *sep[0], 14, *sep[0]]
     b = [1, 2, *sep[0], 4, *sep[1], 6, 7, *sep[2], 9, *sep[3], 6, 7, *sep[0], 9, *sep[0]]
@@ -1084,21 +1086,27 @@ def test_separator():
     def widget_with_separator(a=a[0], b=b[0]):
         return
 
-    def get_all_itemdata(combo_box):
-        return [combo_box.itemData(index) for index in range(combo_box.count())]
+    if backend == "qt":
+        def get_all_itemdata(combo_box):
+            return [combo_box.itemData(index) for index in range(combo_box.count())]
+
+        # Count returns the number of all items including separator items
+        assert widget_with_separator.a.native.count() == 21
+        assert widget_with_separator.b.native.count() == 18
+
+        # Separator singletons themselves are used as separator item data
+        assert get_all_itemdata(widget_with_separator.a.native) == a
+        assert get_all_itemdata(widget_with_separator.b.native) == b2
 
-    # Count returns the number of all items including separator items
-    assert widget_with_separator.a.native.count() == 21
-    assert widget_with_separator.b.native.count() == 18
+    if backend == "ipynb":
+        # Separator singletons themselves are used as separator item data
+        assert widget_with_separator.a.options['choices'] == a
+        assert widget_with_separator.b.options['choices'] == b  # non-separators are not unique
 
     # Choices only returns unique, non-separator items
     assert widget_with_separator.a.choices == (1, 2, 4, 6, 7, 9, 11, 12, 14)
     assert widget_with_separator.b.choices == (1, 2, 4, 6, 7, 9)
 
-    # Separator singletons themselves are used as separator item data
-    assert get_all_itemdata(widget_with_separator.a.native) == a
-    assert get_all_itemdata(widget_with_separator.b.native) == b2
-
 
 def test_float_slider_readout():
     sld = widgets.FloatSlider(value=4, min=0.5, max=10.5)