fix init and add tests

ipykernel/comm/comm.py

@@ -71,6 +71,9 @@ def _default_comm_id(self):
     def __init__(self, *args, **kwargs):
         # Comm takes positional arguments, LoggingConfigurable does not, so we explicitly forward arguments
         traitlets.config.LoggingConfigurable.__init__(self, **kwargs)
+        for name in self.trait_names():
+            if name in kwargs:
+                kwargs.pop(name)
         BaseComm.__init__(self, *args, **kwargs)
 
 

ipykernel/tests/test_comm.py

@@ -1,12 +1,85 @@
-from ipykernel.comm import Comm
+from ipykernel.comm import Comm, CommManager
 from ipykernel.ipkernel import IPythonKernel
 
 
+def test_comm(kernel):
+    manager = CommManager(kernel=kernel)
+    kernel.comm_manager = manager
+
+    c = Comm(kernel=kernel)
+    msgs = []
+
+    def on_close(msg):
+        msgs.append(msg)
+
+    def on_message(msg):
+        msgs.append(msg)
 
-async def test_comm(kernel):
-    c = Comm()
-    c.kernel = kernel  # type:ignore
     c.publish_msg("foo")
+    c.open({})
+    c.on_msg(on_message)
+    c.on_close(on_close)
+    c.handle_msg({})
+    c.handle_close({})
+    c.close()
+    assert len(msgs) == 2
+
+
+def test_comm_manager(kernel):
+    manager = CommManager(kernel=kernel)
+    msgs = []
+
+    def foo(comm, msg):
+        msgs.append(msg)
+        comm.close()
+
+    def fizz(comm, msg):
+        raise RuntimeError('hi')
+
+    def on_close(msg):
+        msgs.append(msg)
+
+    def on_msg(msg):
+        msgs.append(msg)
+
+    manager.register_target("foo", foo)
+    manager.register_target("fizz", fizz)
+
+    kernel.comm_manager = manager
+    comm = Comm()
+    comm.on_msg(on_msg)
+    comm.on_close(on_close)
+    manager.register_comm(comm)
+
+    assert manager.get_comm(comm.comm_id) == comm
+    assert manager.get_comm('foo') is None
+
+    msg = dict(content=dict(comm_id=comm.comm_id, target_name='foo'))
+    manager.comm_open(None, None, msg)
+    assert len(msgs) == 1
+    msg['content']['target_name'] = 'bar'
+    manager.comm_open(None, None, msg)
+    assert len(msgs) == 1
+    msg = dict(content=dict(comm_id=comm.comm_id, target_name='fizz'))
+    manager.comm_open(None, None, msg)
+    assert len(msgs) == 1
+
+    manager.register_comm(comm)
+    assert manager.get_comm(comm.comm_id) == comm
+    msg = dict(content=dict(comm_id=comm.comm_id))
+    manager.comm_msg(None, None, msg)
+    assert len(msgs) == 2
+    msg['content']['comm_id'] = 'foo'
+    manager.comm_msg(None, None, msg)
+    assert len(msgs) == 2
+
+    manager.register_comm(comm)
+    assert manager.get_comm(comm.comm_id) == comm
+    msg = dict(content=dict(comm_id=comm.comm_id))
+    manager.comm_close(None, None, msg)
+    assert len(msgs) == 3
+
+    assert comm._closed
 
 
 def test_comm_in_manager(ipkernel: IPythonKernel) -> None: