diff --git a/IPython/utils/tests/test_jsonutil.py b/IPython/utils/tests/test_jsonutil.py
index f70e941..61f1df7 100644
--- a/IPython/utils/tests/test_jsonutil.py
+++ b/IPython/utils/tests/test_jsonutil.py
@@ -11,6 +11,7 @@
 # Imports
 #-----------------------------------------------------------------------------
 # stdlib
+import datetime
 import json
 from base64 import decodestring
 
@@ -19,6 +20,7 @@ import nose.tools as nt
 
 # our own
 from IPython.testing import decorators as dec
+from IPython.utils import jsonutil, tz
 from ..jsonutil import json_clean, encode_images
 from ..py3compat import unicode_to_str, str_to_bytes
 
@@ -94,6 +96,33 @@ def test_lambda():
     assert '<lambda>' in jc
     json.dumps(jc)
 
+def test_extract_dates():
+    timestamps = [
+        '2013-07-03T16:34:52.249482',
+        '2013-07-03T16:34:52.249482Z',
+        '2013-07-03T16:34:52.249482Z-0800',
+        '2013-07-03T16:34:52.249482Z+0800',
+        '2013-07-03T16:34:52.249482Z+08:00',
+        '2013-07-03T16:34:52.249482Z-08:00',
+        '2013-07-03T16:34:52.249482-0800',
+        '2013-07-03T16:34:52.249482+0800',
+        '2013-07-03T16:34:52.249482+08:00',
+        '2013-07-03T16:34:52.249482-08:00',
+    ]
+    extracted = jsonutil.extract_dates(timestamps)
+    ref = extracted[0]
+    for dt in extracted:
+        nt.assert_true(isinstance(dt, datetime.datetime))
+        nt.assert_equal(dt, ref)
+
+def test_date_default():
+    data = dict(today=datetime.datetime.now(), utcnow=tz.utcnow())
+    jsondata = json.dumps(data, default=jsonutil.date_default)
+    nt.assert_in("+00", jsondata)
+    nt.assert_equal(jsondata.count("+00"), 1)
+    extracted = jsonutil.extract_dates(json.loads(jsondata))
+    for dt in extracted.values():
+        nt.assert_true(isinstance(dt, datetime.datetime))
 
 def test_exception():
     bad_dicts = [{1:'number', '1':'string'},