Fix constructor of CommunicationOptions

Fix #44768

PiperOrigin-RevId: 341888489
Change-Id: I625f2e5412a217a95e3306fc6345f378b932071b

tensorflow/python/distribute/collective_util.py

@@ -81,7 +81,11 @@ class _OptionsExported(object):
   """
 
   def __new__(cls, *args, **kwargs):
-    return Options.__new__(Options, *args, **kwargs)
+    # We expose a dummy class so that we can separate internal and public APIs.
+    # Note that __init__ won't be called on the returned object if it's a
+    # different class [1].
+    # [1] https://docs.python.org/3/reference/datamodel.html#object.__new__
+    return Options(*args, **kwargs)
 
   def __init__(self,
                bytes_per_pack=0,

tensorflow/python/distribute/collective_util_test.py

@@ -25,8 +25,11 @@ from tensorflow.python.eager import test
 class OptionsTest(test.TestCase):
 
   def testCreateOptionsViaExportedAPI(self):
-    options = collective_util._OptionsExported()
+    options = collective_util._OptionsExported(bytes_per_pack=1)
     self.assertIsInstance(options, collective_util.Options)
+    self.assertEqual(options.bytes_per_pack, 1)
+    with self.assertRaises(ValueError):
+      collective_util._OptionsExported(bytes_per_pack=-1)
 
   def testCreateOptionsViaHints(self):
     with self.assertLogs() as cm: