Fix '_time_from_iso8601_time_naive' for values with micros. (#5756)

Closes #5750.

Author: tseaver

core/google/cloud/_helpers.py

@@ -43,6 +43,8 @@
 _NOW = datetime.datetime.utcnow  # To be replaced by tests.
 _RFC3339_MICROS = '%Y-%m-%dT%H:%M:%S.%fZ'
 _RFC3339_NO_FRACTION = '%Y-%m-%dT%H:%M:%S'
+_TIMEONLY_W_MICROS = '%H:%M:%S.%f'
+_TIMEONLY_NO_FRACTION = '%H:%M:%S'
 # datetime.strptime cannot handle nanosecond precision:  parse w/ regex
 _RFC3339_NANOS = re.compile(r"""
     (?P<no_fraction>
@@ -256,9 +258,15 @@ def _time_from_iso8601_time_naive(value):
 
     :rtype: :class:`datetime.time`
     :returns: A datetime time object created from the string
-
+    :raises ValueError: if the value does not match a known format.
     """
-    return datetime.datetime.strptime(value, '%H:%M:%S').time()
+    if len(value) == 8:  # HH:MM:SS
+        fmt = _TIMEONLY_NO_FRACTION
+    elif len(value) == 15:  # HH:MM:SS.micros
+        fmt = _TIMEONLY_W_MICROS
+    else:
+        raise ValueError("Unknown time format: {}".format(value))
+    return datetime.datetime.strptime(value, fmt).time()
 
 
 def _rfc3339_to_datetime(dt_str):

core/tests/unit/test__helpers.py

@@ -298,6 +298,16 @@ def test_todays_date(self):
         WHEN = datetime.time(12, 9, 42)
         self.assertEqual(self._call_fut(("12:09:42")), WHEN)
 
+    def test_w_microseconds(self):
+        import datetime
+
+        WHEN = datetime.time(12, 9, 42, 123456)
+        self.assertEqual(self._call_fut(("12:09:42.123456")), WHEN)
+
+    def test_w_millis_fail(self):
+        with self.assertRaises(ValueError):
+            self._call_fut("12:09:42.123")
+
 
 class Test__rfc3339_to_datetime(unittest.TestCase):