MAINT: Add GC tests

.ci/azure-pipelines.yml

@@ -114,6 +114,11 @@ jobs:
         python.version: '3.6'
       Python37:
         python.version: '3.7'
+      Python38:
+        python.version: '3.8'
+        variables:
+          PYVISTA_PRE: true
+          GC_TEST: true
 
   steps:
   - task: UsePythonVersion@0
@@ -123,6 +128,9 @@ jobs:
 
   - script: |
       pip install wheel --upgrade
+      if [ "$PYVISTA_PRE" == "true" ]; then
+        pip install https://github.com/larsoner/pyvista/zipball/mem
+      fi;
       python setup.py bdist_wheel
       pip install dist/pyvistaqt*.whl
     displayName: Build wheel and install pyvistaqt
@@ -369,7 +377,7 @@ jobs:
     displayName: Upload Documentation to pyvistaqt-docs
     env:
       GH_TOKEN: $(gh.token)
-    condition: and(succeeded(), eq(variables['Build.SourceBranch'], 'refs/heads/master'))    
+    condition: and(succeeded(), eq(variables['Build.SourceBranch'], 'refs/heads/master'))
 
   # don't run job on no-ci builds
   condition: not(contains(variables['System.PullRequest.SourceBranch'], 'no-ci'))

pyvistaqt/editor.py

@@ -1,5 +1,6 @@
 """This module contains the Qt scene editor."""
 
+import weakref
 from typing import List
 
 import vtk
@@ -105,9 +106,10 @@ def _get_actor_widget(actor: vtk.vtkActor) -> QWidget:
     prop = actor.GetProperty()
 
     # visibility
+    sv = weakref.ref(actor.SetVisibility)
     visibility = QCheckBox("Visibility")
     visibility.setChecked(actor.GetVisibility())
-    visibility.toggled.connect(actor.SetVisibility)
+    visibility.toggled.connect(lambda v: sv()(v))
     layout.addWidget(visibility)
 
     if prop is not None:
@@ -116,7 +118,8 @@ def _get_actor_widget(actor: vtk.vtkActor) -> QWidget:
         opacity = QDoubleSpinBox()
         opacity.setMaximum(1.0)
         opacity.setValue(prop.GetOpacity())
-        opacity.valueChanged.connect(prop.SetOpacity)
+        so = weakref.ref(prop.SetOpacity)
+        opacity.valueChanged.connect(lambda v: so()(v))
         tmp_layout.addWidget(QLabel("Opacity"))
         tmp_layout.addWidget(opacity)
         layout.addLayout(tmp_layout)

pyvistaqt/plotting.py

@@ -474,6 +474,7 @@ def close(self) -> None:
         if hasattr(self, "render_timer"):
             self.render_timer.stop()
         BasePlotter.close(self)
+        BasePlotter.deep_clean(self)
         QVTKRenderWindowInteractor.close(self)
 
 
@@ -810,6 +811,14 @@ def __del__(self) -> None:  # pragma: no cover
         """Delete the qt plotter."""
         if not self._closed:
             self.app_window.close()
+        # Qt LeaveEvent requires _Iren so we use _FakeIren instead of None
+        # to resolve the ref to vtkGenericRenderWindowInteractor
+        self._Iren = _FakeEventHandler()
+        for key in ('_RenderWindow', 'renderer'):
+            try:
+                setattr(self, key, None)
+            except AttributeError:
+                pass
 
     def add_callback(
         self, func: Callable, interval: int = 1000, count: Optional[int] = None
@@ -856,3 +865,26 @@ def _create_menu_bar(parent: Any) -> QMenuBar:
     if parent is not None:
         parent.setMenuBar(menu_bar)
     return menu_bar
+
+
+class _FakeEventHandler():
+    def SetDPI(self, dpi):
+        pass
+
+    def EnterEvent(self):
+        pass
+
+    def MouseMoveEvent(self):
+        pass
+
+    def LeaveEvent(self):
+        pass
+
+    def SetEventInformation(self, *args, **kwargs):
+        pass
+
+    def SetSize(self, *args, **kwargs):
+        pass
+
+    def ConfigureEvent(self, *args, **kwargs):
+        pass

tests/test_plotting.py

@@ -1,5 +1,7 @@
+import gc
 import os
 import platform
+import weakref
 
 import numpy as np
 import pytest
@@ -20,6 +22,38 @@
 NO_PLOTTING = not system_supports_plotting()
 
 
+# Adapted from PyVista
+def _is_vtk(obj):
+    try:
+        return obj.__class__.__name__.startswith('vtk')
+    except Exception:  # old Python sometimes no __class__.__name__
+        return False
+
+
+@pytest.fixture(autouse=True)
+def check_gc(request):
+    """Ensure that all VTK objects are garbage-collected by Python."""
+    if 'test_ipython' in request.node.name:  # XXX this keeps a ref
+        yield
+        return
+    # We need https://github.com/pyvista/pyvista/pull/958 to actually run
+    # this test. Eventually we should use LooseVersion, but as of 2020/10/22
+    # 0.26.1 is the latest PyPi version and on master the version is weirdly
+    # 0.26.0 (as opposed to 0.26.2.dev0 or 0.27.dev0) so we can't. So for now
+    # let's use an env var (GC_TEST) instead of:
+    # if LooseVersion(pyvista.__version__) < LooseVersion('0.26.2'):
+    if os.getenv('GC_TEST', '').lower() != 'true':
+        yield
+        return
+    before = set(id(o) for o in gc.get_objects() if _is_vtk(o))
+    yield
+    pyvista.close_all()
+    gc.collect()
+    after = [o for o in gc.get_objects() if _is_vtk(o) and id(o) not in before]
+    after = sorted(o.__class__.__name__ for o in after)
+    assert len(after) == 0, 'Not all objects GCed:\n' + '\n'.join(after)
+
+
 class TstWindow(MainWindow):
     def __init__(self, parent=None, show=True, off_screen=True):
         MainWindow.__init__(self, parent)
@@ -140,7 +174,8 @@ def test_editor(qtbot):
 
     # add at least an actor
     plotter.subplot(0, 0)
-    plotter.add_mesh(pyvista.Sphere())
+    pd = pyvista.Sphere()
+    actor = plotter.add_mesh(pd)
     plotter.subplot(1, 0)
     plotter.show_axes()
 
@@ -178,6 +213,7 @@ def test_editor(qtbot):
 
     # hide the editor for coverage
     editor.toggle()
+    plotter.remove_actor(actor)
     plotter.close()
 
     plotter = BackgroundPlotter(editor=False)
@@ -524,10 +560,10 @@ def test_background_plotting_menu_bar(qtbot):
 def test_background_plotting_add_callback(qtbot, monkeypatch):
     class CallBack(object):
         def __init__(self, sphere):
-            self.sphere = sphere
+            self.sphere = weakref.ref(sphere)
 
         def __call__(self):
-            self.sphere.points *= 0.5
+            self.sphere().points[:] = self.sphere().points * 0.5
 
     update_count = [0]
     orig_update_app_icon = BackgroundPlotter.update_app_icon