fix(tests): fix two CI failures in plugin tests on offscreen platform

- test_plugin_system: force-enable plugin actions before triggering
  them, since QAction.trigger() is a no-op on disabled actions and
  the workspace has 0 objects (SelectCond.at_least_one disables them)
- test_plugin_description_toggle: fix ExpandableTextWidget._get_text_width()
  to fall back to minimumWidth() when width() returns 0 on unshown
  widgets (offscreen QPA platform)

Author: PierreRaybaut

datalab/tests/features/plugins/test_plugins.py

@@ -260,6 +260,10 @@ def test_plugin_system():  # pylint: disable=too-many-statements
             found_action = False
             for act in actions:
                 if act.text() == "Action Plugin 2 Updated_common":
+                    # Force-enable the action: with 0 items in the workspace
+                    # it is disabled by SelectCond.at_least_one, and
+                    # QAction.trigger() is a no-op on disabled actions.
+                    act.setEnabled(True)
                     act.trigger()
                     found_action = True
                     break
@@ -331,6 +335,7 @@ def test_plugin_system():  # pylint: disable=too-many-statements
             found_action = False
             for act in actions:
                 if act.text() == "Action Plugin 2 Updated_common":
+                    act.setEnabled(True)
                     act.trigger()
                     found_action = True
                     break

datalab/widgets/expandabletext.py

@@ -212,7 +212,11 @@ def _get_text_width(self) -> int:
         width = self.label.viewport().width()
         if width <= 0:
             margins = self.layout().contentsMargins()
-            width = self.width() - margins.left() - margins.right()
+            widget_width = self.width()
+            if widget_width <= 0:
+                # Widget not yet shown: honour setFixedWidth / setMinimumWidth
+                widget_width = self.minimumWidth()
+            width = widget_width - margins.left() - margins.right()
         return max(width, 0)
 
     def _get_collapsed_height(self) -> int: