fix: harden Wayland compositor runtime checks

tests/test_compositor_state_adapter_regressions.py

@@ -110,6 +110,31 @@ class CompositorStateAdapterRegressionTests(unittest.TestCase):
 
         sourceRemove.assert_called_once_with(41)
 
+    def test_wayland_backend_logs_activation_failure_reason(self) -> None:
+        fakeDisplay = mock.Mock()
+        fakeDisplay.connect.side_effect = ValueError("Unable to connect to display")
+        fakeProtocols = mock.Mock()
+        fakeProtocols.has_runtime_support.return_value = True
+        fakeProtocols.get_display_class.return_value = mock.Mock(return_value=fakeDisplay)
+        backend = compositor_state_wayland.WaylandSharedProtocolsBackend(
+            environment={"WAYLAND_DISPLAY": "wayland-0"},
+            protocols=fakeProtocols,
+        )
+
+        with (
+            mock.patch.object(compositor_state_wayland, "get_session_type", return_value="wayland"),
+            mock.patch.object(compositor_state_wayland.debug, "printMessage") as printMessage,
+        ):
+            backend.activate(mock.Mock())
+
+        printMessage.assert_any_call(
+            compositor_state_wayland.debug.LEVEL_WARNING,
+            mock.ANY,
+            True,
+        )
+        self.assertIn("Unable to connect to display", printMessage.call_args_list[-1].args[1])
+        self.assertIsNone(backend._display)
+
     def test_local_ext_workspace_wrapper_supports_base_pywayland_without_distro_protocol_module(self) -> None:
         fakeClientModule = types.ModuleType("pywayland.client")
 
@@ -234,7 +259,8 @@ class CompositorStateAdapterRegressionTests(unittest.TestCase):
             backend_name="wayland-shared-protocols",
         )
 
-        workspace.activate(adapter._handle_workspace_signal)
+        with mock.patch.object(workspace, "is_available", return_value=False):
+            workspace.activate(adapter._handle_workspace_signal)
         workspace._handle_workspace_state(first_workspace, "active", True)
         workspace._handle_workspace_manager_done()