Fix Python 3.7 test

python/ipywidgets/ipywidgets/widgets/tests/utils.py

@@ -4,7 +4,13 @@
 from ipywidgets import Widget
 import ipywidgets.widgets.widget
 
-import comm
+# The new comm package is not available in our Python 3.7 CI (older ipykernel version)
+try:
+    import comm
+    NEW_COMM_PACKAGE = True
+except ImportError:
+    NEW_COMM_PACKAGE = False
+
 from ipykernel.comm import Comm
 
 
@@ -40,12 +46,17 @@ def dummy_get_comm_manager(**kwargs):
 _widget_attrs = {}
 undefined = object()
 
-orig_create_comm = comm.create_comm
-orig_get_comm_manager = comm.get_comm_manager
+orig_create_comm = None
+orig_get_comm_manager = None
+
+if NEW_COMM_PACKAGE:
+    orig_create_comm = comm.create_comm
+    orig_get_comm_manager = comm.get_comm_manager
 
 def setup_test_comm():
-    comm.create_comm = dummy_create_comm
-    comm.get_comm_manager = dummy_get_comm_manager
+    if NEW_COMM_PACKAGE:
+        comm.create_comm = dummy_create_comm
+        comm.get_comm_manager = dummy_get_comm_manager
     Widget.comm.klass = DummyComm
     ipywidgets.widgets.widget.Comm = DummyComm
     _widget_attrs['_repr_mimebundle_'] = Widget._repr_mimebundle_
@@ -54,8 +65,9 @@ def raise_not_implemented(*args, **kwargs):
     Widget._repr_mimebundle_ = raise_not_implemented
 
 def teardown_test_comm():
-    comm.create_comm = orig_create_comm
-    comm.get_comm_manager = orig_get_comm_manager
+    if NEW_COMM_PACKAGE:
+        comm.create_comm = orig_create_comm
+        comm.get_comm_manager = orig_get_comm_manager
     Widget.comm.klass = Comm
     ipywidgets.widgets.widget.Comm = Comm
     for attr, value in _widget_attrs.items():