fix: Handle conversions for naive datetime values

Author: Mike Kistler

ibm_cloud_sdk_core/utils.py

@@ -71,13 +71,19 @@ def cleanup_value(value: any) -> any:
 def datetime_to_string(val: datetime.datetime) -> str:
     """Convert a datetime object to string.
 
+    If the supplied datetime does not specify a timezone,
+    it is assumed to be UTC.
+
     Args:
         val: The datetime object.
 
     Returns:
         datetime serialized to iso8601 format.
     """
     if isinstance(val, datetime.datetime):
+        if val.tzinfo is None:
+            return val.isoformat() + 'Z'
+        val = val.astimezone(datetime.timezone.utc)
         return val.isoformat().replace('+00:00', 'Z')
     return val
 
@@ -90,7 +96,10 @@ def string_to_datetime(string: str) -> datetime.datetime:
     Returns:
         the de-serialized string as a datetime object.
     """
-    return date_parser.parse(string)
+    val = date_parser.parse(string)
+    if val.tzinfo is not None:
+        return val
+    return val.replace(tzinfo=datetime.timezone.utc)
 
 def date_to_string(val: datetime.date) -> str:
     """Convert a date object to string.

test/test_utils.py

@@ -1,17 +1,45 @@
 # pylint: disable=missing-docstring
+import datetime
 import os
 
 from ibm_cloud_sdk_core import string_to_datetime, datetime_to_string, get_authenticator_from_environment
 from ibm_cloud_sdk_core import string_to_date, date_to_string
 from ibm_cloud_sdk_core import convert_model, convert_list
 from ibm_cloud_sdk_core.authenticators import BasicAuthenticator, IAMAuthenticator
 
-def test_datetime_conversion():
+def test_string_to_datetime():
+    # If the specified string does not include a timezone, it is assumed to be UTC
     date = string_to_datetime('2017-03-06 16:00:04.159338')
     assert date.day == 6
-    res = datetime_to_string(date)
-    assert res == '2017-03-06T16:00:04.159338'
+    assert date.hour == 16
+    assert date.tzinfo.utcoffset(None) == datetime.timezone.utc.utcoffset(None)
+    # Test date string with TZ specified as '+xxxx'
+    date = string_to_datetime('2017-03-06 16:00:04.159338+0600')
+    assert date.day == 6
+    assert date.hour == 16
+    assert date.tzinfo.utcoffset(None).total_seconds() == 6*60*60
+    # Test date string with TZ specified as 'Z'
+    date = string_to_datetime('2017-03-06 16:00:04.159338Z')
+    assert date.day == 6
+    assert date.hour == 16
+    assert date.tzinfo.utcoffset(None) == datetime.timezone.utc.utcoffset(None)
+
+def test_datetime_to_string():
+    # If specified date is None, return None
     assert datetime_to_string(None) is None
+    # If the specified date is "naive", it is interpreted as a UTC date
+    date = datetime.datetime(2017, 3, 6, 16, 0, 4, 159338)
+    res = datetime_to_string(date)
+    assert res == '2017-03-06T16:00:04.159338Z'
+    # Test date with UTC timezone
+    date = datetime.datetime(2017, 3, 6, 16, 0, 4, 159338, datetime.timezone.utc)
+    res = datetime_to_string(date)
+    assert res == '2017-03-06T16:00:04.159338Z'
+    # Test date with non-UTC timezone
+    tzn = datetime.timezone(datetime.timedelta(hours=-6))
+    date = datetime.datetime(2017, 3, 6, 10, 0, 4, 159338, tzn)
+    res = datetime_to_string(date)
+    assert res == '2017-03-06T16:00:04.159338Z'
 
 def test_date_conversion():
     date = string_to_date('2017-03-06')