Add regression test for bug that caused histogram viewer to crash whe…

…n removing datasets from the DataCollection

glue_jupyter/bqplot/histogram/tests/test_viewer.py

@@ -17,7 +17,7 @@ def test_non_hex_colors(app, dataxyz):
     dataxyz.subsets[0].style.color = 'purple'
 
 
-def test_remove(app, dataxz, dataxyz):
+def test_remove_from_viewer(app, dataxz, dataxyz):
     s = app.histogram1d(data=dataxyz)
     s.add_data(dataxz)
     app.data_collection.new_subset_group(subset_state=dataxz.id['x'] > 1, label='test')
@@ -28,6 +28,20 @@ def test_remove(app, dataxz, dataxyz):
     assert len(s.figure.marks) == 0
 
 
+def test_remove_from_data_collection(app, dataxz, dataxyz):
+    s = app.histogram1d(data=dataxyz)
+    s.add_data(dataxz)
+    app.data_collection.new_subset_group(subset_state=dataxz.id['x'] > 1, label='test')
+    assert len(s.figure.marks) == 4
+    s.state.hist_n_bin = 30
+    app.data_collection.remove(dataxyz)
+    assert len(s.figure.marks) == 2
+    s.state.hist_n_bin = 20
+    app.data_collection.remove(dataxz)
+    assert len(s.figure.marks) == 0
+    s.state.hist_n_bin = 10
+
+
 def test_redraw_empty_subset(app, dataxz):
     s = app.histogram1d(data=dataxz)
     s.add_data(dataxz)