MNT: set default canvas when un-pickling

tacaswell · tacaswell · commit 6c64ea732667 · 2020-01-12T00:41:16.000-05:00
In 380c531 / #12450 we set the default canvas on Figure `__init__` to FigureCanvasBase but were still setting it to `None` in `__setstate__`.
diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
@@ -1999,7 +1999,7 @@ def __setstate__(self, state):
 
         # re-initialise some of the unstored state information
         self._axobservers = []
-        self.canvas = None
+        FigureCanvasBase(self)  # Set self.canvas.
         self._layoutbox = None
 
         if restore_to_pylab:
diff --git a/lib/matplotlib/tests/test_pickle.py b/lib/matplotlib/tests/test_pickle.py
@@ -5,11 +5,15 @@
 import numpy as np
 import pytest
 
+import pickle
+import io
+
 from matplotlib import cm
 from matplotlib.testing.decorators import image_comparison
 from matplotlib.dates import rrulewrapper
 import matplotlib.pyplot as plt
 import matplotlib.transforms as mtransforms
+import matplotlib.figure as mfigure
 
 
 def test_simple():
@@ -194,3 +198,13 @@ def test_shared():
 @pytest.mark.parametrize("cmap", cm.cmap_d.values())
 def test_cmap(cmap):
     pickle.dumps(cmap)
+
+
+def test_unpickle_canvas():
+    fig = mfigure.Figure()
+    assert fig.canvas is not None
+    out = io.BytesIO()
+    pickle.dump(fig, out)
+    out.seek(0)
+    fig2 = pickle.load(out)
+    assert fig2.canvas is not None
