TST: verify that dpi is restored on close

Author: tacaswell

lib/matplotlib/tests/test_backend_qt.py

@@ -215,6 +215,10 @@ def set_device_pixel_ratio(ratio):
         assert qt_canvas.get_width_height() == (600, 240)
         assert (fig.get_size_inches() == (5, 2)).all()
 
+        # check that closing the figure restores the original dpi
+        plt.close(fig)
+        assert fig.dpi == 120
+
 
 @pytest.mark.backend('QtAgg', skip_on_importerror=True)
 def test_subplottool():