Make the isatty method of OutStream return True

ipykernel/iostream.py

@@ -320,7 +320,7 @@ def _watch_pipe_fd(self):
             self._exc = sys.exc_info()
 
     def __init__(
-        self, session, pub_thread, name, pipe=None, echo=None, *, watchfd=True
+        self, session, pub_thread, name, pipe=None, echo=None, *, watchfd=True, isatty=False,
     ):
         """
         Parameters
@@ -333,6 +333,8 @@ def __init__(
             the file descriptor by its number. It will spawn a watching thread,
             that will swap the give file descriptor for a pipe, read from the
             pipe, and insert this into the current Stream.
+        isatty : bool (default, False)
+            Indication of whether this stream has termimal capabilities (e.g. can handle colors)
 
         """
         if pipe is not None:
@@ -364,6 +366,7 @@ def __init__(
         self._io_loop = pub_thread.io_loop
         self._new_buffer()
         self.echo = None
+        self._isatty = bool(isatty)
 
         if (
             watchfd
@@ -381,6 +384,14 @@ def __init__(
             else:
                 raise ValueError("echo argument must be a file like object")
 
+    def isatty(self):
+        """Return a bool indicating whether this is an 'interactive' stream.
+
+        Returns:
+            Boolean
+        """
+        return self._isatty
+
     def _setup_stream_redirects(self, name):
         pr, pw = os.pipe()
         fno = getattr(sys, name).fileno()

ipykernel/tests/test_io.py

@@ -38,3 +38,13 @@ def test_io_api():
         stream.seek(0)
     with nt.assert_raises(io.UnsupportedOperation):
         stream.tell()
+
+def test_io_isatty():
+    session = Session()
+    ctx = zmq.Context()
+    pub = ctx.socket(zmq.PUB)
+    thread = IOPubThread(pub)
+    thread.start()
+
+    stream = OutStream(session, thread, 'stdout', isatty=True)
+    assert stream.isatty()