Fix interact test

IPython/html/widgets/tests/test_interaction.py

@@ -80,7 +80,8 b' def check_widgets(container, **to_check):'
     # build a widget dictionary, so it matches
     widgets = {}
     for w in container.children:
-        widgets[w.description] = w
+        if hasattr(w, 'description'):
+            widgets[w.description] = w
     
     for key, d in to_check.items():
         nt.assert_in(key, widgets)
@@ -138,7 +139,7 b' def test_single_value_float():'
 def test_single_value_int():
     for a in (1, 5, -3):
         c = interactive(f, a=a)
-        nt.assert_equal(len(c.children), 1)
+        nt.assert_equal(len(c.children), 2)
         w = c.children[0]
         check_widget(w,
             cls=widgets.IntSlider,
@@ -157,7 +158,7 b' def test_list_tuple_2_int():'
         c = interactive(f, tup=(1,-1))
     for min, max in [ (0,1), (1,10), (1,2), (-5,5), (-20,-19) ]:
         c = interactive(f, tup=(min, max), lis=[min, max])
-        nt.assert_equal(len(c.children), 2)
+        nt.assert_equal(len(c.children), 3)
         d = dict(
             cls=widgets.IntSlider,
             min=min,
@@ -174,7 +175,7 b' def test_list_tuple_3_int():'
         c = interactive(f, tup=(1,2,-1))
     for min, max, step in [ (0,2,1), (1,10,2), (1,100,2), (-5,5,4), (-100,-20,4) ]:
         c = interactive(f, tup=(min, max, step), lis=[min, max, step])
-        nt.assert_equal(len(c.children), 2)
+        nt.assert_equal(len(c.children), 3)
         d = dict(
             cls=widgets.IntSlider,
             min=min,
@@ -191,7 +192,7 b' def test_list_tuple_2_float():'
         c = interactive(f, tup=(0.5,-0.5))
     for min, max in [ (0.5, 1.5), (1.1,10.2), (1,2.2), (-5.,5), (-20,-19.) ]:
         c = interactive(f, tup=(min, max), lis=[min, max])
-        nt.assert_equal(len(c.children), 2)
+        nt.assert_equal(len(c.children), 3)
         d = dict(
             cls=widgets.FloatSlider,
             min=min,
@@ -210,7 +211,7 b' def test_list_tuple_3_float():'
         c = interactive(f, tup=(1,2.,-1.))
     for min, max, step in [ (0.,2,1), (1,10.,2), (1,100,2.), (-5.,5.,4), (-100,-20.,4.) ]:
         c = interactive(f, tup=(min, max, step), lis=[min, max, step])
-        nt.assert_equal(len(c.children), 2)
+        nt.assert_equal(len(c.children), 3)
         d = dict(
             cls=widgets.FloatSlider,
             min=min,
@@ -224,7 +225,7 b' def test_list_tuple_str():'
     values = ['hello', 'there', 'guy']
     first = values[0]
     c = interactive(f, tup=tuple(values), lis=list(values))
-    nt.assert_equal(len(c.children), 2)
+    nt.assert_equal(len(c.children), 3)
     d = dict(
         cls=widgets.Dropdown,
         value=first,
@@ -471,7 +472,7 b' def test_call_decorated_kwargs_on_trait_change():'
 
 def test_fixed():
     c = interactive(f, a=widgets.fixed(5), b='text')
-    nt.assert_equal(len(c.children), 1)
+    nt.assert_equal(len(c.children), 2)
     w = c.children[0]
     check_widget(w,
         cls=widgets.Text,

IPython/html/widgets/widget_output.py

@@ -37,7 +37,11 b' class Output(DOMWidget):'
     def __init__(self, *args, **kwargs):
         super(Output, self).__init__(*args, **kwargs)
         from IPython import get_ipython
-        self._ip = get_ipython()
+        ip = get_ipython()
+        if ip is not None and hasattr(ip, 'kernel'):
+            self._kernel = ip.kernel
+        else:
+            self._kernel = None
 
     def clear_output(self, *pargs, **kwargs):
         with self:
@@ -45,37 +49,38 b' class Output(DOMWidget):'
 
     def __enter__(self):
         """Called upon entering output widget context manager."""
-        self._flush()
-        kernel = self._ip.kernel
-        session = kernel.session
-        send = session.send
-        self._original_send = send
-        self._session = session
-
-        def send_hook(stream, msg_or_type, content=None, parent=None, ident=None,
-             buffers=None, track=False, header=None, metadata=None): 
-
-            # Handle both prebuild messages and unbuilt messages.
-            if isinstance(msg_or_type, (Message, dict)):
-                msg_type = msg_or_type['msg_type']
-                msg = dict(msg_or_type)
-            else:
-                msg_type = msg_or_type
-                msg = session.msg(msg_type, content=content, parent=parent, 
-                    header=header, metadata=metadata)
-
-            # If this is a message type that we want to forward, forward it.
-            if stream is kernel.iopub_socket and msg_type in ['clear_output', 'stream', 'display_data']:
-                self.send(msg)
-            else: 
-                send(stream, msg, ident=ident, buffers=buffers, track=track)
-
-        session.send = send_hook
+        if self._kernel is not None:
+            self._flush()
+            session = self._kernel.session
+            send = session.send
+            self._original_send = send
+            self._session = session
+
+            def send_hook(stream, msg_or_type, content=None, parent=None, ident=None,
+                 buffers=None, track=False, header=None, metadata=None): 
+
+                # Handle both prebuild messages and unbuilt messages.
+                if isinstance(msg_or_type, (Message, dict)):
+                    msg_type = msg_or_type['msg_type']
+                    msg = dict(msg_or_type)
+                else:
+                    msg_type = msg_or_type
+                    msg = session.msg(msg_type, content=content, parent=parent, 
+                        header=header, metadata=metadata)
+
+                # If this is a message type that we want to forward, forward it.
+                if stream is self._kernel.iopub_socket and msg_type in ['clear_output', 'stream', 'display_data']:
+                    self.send(msg)
+                else: 
+                    send(stream, msg, ident=ident, buffers=buffers, track=track)
+
+            session.send = send_hook
 
     def __exit__(self, exception_type, exception_value, traceback):
         """Called upon exiting output widget context manager."""
-        self._flush()
-        self._session.send = self._original_send
+        if self._kernel is not None:
+            self._flush()
+            self._session.send = self._original_send
 
     def _flush(self):
         """Flush stdout and stderr buffers."""