fix: Dates before 1000AD should use 4-digit years (#1132)

This is required for compliance with RFC3339/ISO8401 and timestamps
which do not comply will be rejected by Spanner.

Fixes #1131

google/cloud/spanner_v1/_helpers.py

@@ -24,7 +24,6 @@
 
 from google.api_core import datetime_helpers
 from google.cloud._helpers import _date_from_iso8601_date
-from google.cloud._helpers import _datetime_to_rfc3339
 from google.cloud.spanner_v1 import TypeCode
 from google.cloud.spanner_v1 import ExecuteSqlRequest
 from google.cloud.spanner_v1 import JsonObject
@@ -122,6 +121,40 @@ def _assert_numeric_precision_and_scale(value):
         raise ValueError(NUMERIC_MAX_PRECISION_ERR_MSG.format(precision + scale))
 
 
+def _datetime_to_rfc3339(value):
+    """Format the provided datatime in the RFC 3339 format.
+
+    :type value: datetime.datetime
+    :param value: value to format
+
+    :rtype: str
+    :returns: RFC 3339 formatted datetime string
+    """
+    # Convert to UTC and then drop the timezone so we can append "Z" in lieu of
+    # allowing isoformat to append the "+00:00" zone offset.
+    value = value.astimezone(datetime.timezone.utc).replace(tzinfo=None)
+    return value.isoformat(sep="T", timespec="microseconds") + "Z"
+
+
+def _datetime_to_rfc3339_nanoseconds(value):
+    """Format the provided datatime in the RFC 3339 format.
+
+    :type value: datetime_helpers.DatetimeWithNanoseconds
+    :param value: value to format
+
+    :rtype: str
+    :returns: RFC 3339 formatted datetime string
+    """
+
+    if value.nanosecond == 0:
+        return _datetime_to_rfc3339(value)
+    nanos = str(value.nanosecond).rjust(9, "0").rstrip("0")
+    # Convert to UTC and then drop the timezone so we can append "Z" in lieu of
+    # allowing isoformat to append the "+00:00" zone offset.
+    value = value.astimezone(datetime.timezone.utc).replace(tzinfo=None)
+    return "{}.{}Z".format(value.isoformat(sep="T", timespec="seconds"), nanos)
+
+
 def _make_value_pb(value):
     """Helper for :func:`_make_list_value_pbs`.
 
@@ -150,9 +183,9 @@ def _make_value_pb(value):
                 return Value(string_value="-Infinity")
         return Value(number_value=value)
     if isinstance(value, datetime_helpers.DatetimeWithNanoseconds):
-        return Value(string_value=value.rfc3339())
+        return Value(string_value=_datetime_to_rfc3339_nanoseconds(value))
     if isinstance(value, datetime.datetime):
-        return Value(string_value=_datetime_to_rfc3339(value, ignore_zone=False))
+        return Value(string_value=_datetime_to_rfc3339(value))
     if isinstance(value, datetime.date):
         return Value(string_value=value.isoformat())
     if isinstance(value, bytes):

tests/unit/test__helpers.py

@@ -190,6 +190,15 @@ def test_w_date(self):
         self.assertIsInstance(value_pb, Value)
         self.assertEqual(value_pb.string_value, today.isoformat())
 
+    def test_w_date_pre1000ad(self):
+        import datetime
+        from google.protobuf.struct_pb2 import Value
+
+        when = datetime.date(800, 2, 25)
+        value_pb = self._callFUT(when)
+        self.assertIsInstance(value_pb, Value)
+        self.assertEqual(value_pb.string_value, "0800-02-25")
+
     def test_w_timestamp_w_nanos(self):
         import datetime
         from google.protobuf.struct_pb2 import Value
@@ -200,7 +209,19 @@ def test_w_timestamp_w_nanos(self):
         )
         value_pb = self._callFUT(when)
         self.assertIsInstance(value_pb, Value)
-        self.assertEqual(value_pb.string_value, when.rfc3339())
+        self.assertEqual(value_pb.string_value, "2016-12-20T21:13:47.123456789Z")
+
+    def test_w_timestamp_w_nanos_pre1000ad(self):
+        import datetime
+        from google.protobuf.struct_pb2 import Value
+        from google.api_core import datetime_helpers
+
+        when = datetime_helpers.DatetimeWithNanoseconds(
+            850, 12, 20, 21, 13, 47, nanosecond=123456789, tzinfo=datetime.timezone.utc
+        )
+        value_pb = self._callFUT(when)
+        self.assertIsInstance(value_pb, Value)
+        self.assertEqual(value_pb.string_value, "0850-12-20T21:13:47.123456789Z")
 
     def test_w_listvalue(self):
         from google.protobuf.struct_pb2 import Value
@@ -214,12 +235,20 @@ def test_w_listvalue(self):
     def test_w_datetime(self):
         import datetime
         from google.protobuf.struct_pb2 import Value
-        from google.api_core import datetime_helpers
 
-        now = datetime.datetime.utcnow().replace(tzinfo=datetime.timezone.utc)
-        value_pb = self._callFUT(now)
+        when = datetime.datetime(2021, 2, 8, 0, 0, 0, tzinfo=datetime.timezone.utc)
+        value_pb = self._callFUT(when)
+        self.assertIsInstance(value_pb, Value)
+        self.assertEqual(value_pb.string_value, "2021-02-08T00:00:00.000000Z")
+
+    def test_w_datetime_pre1000ad(self):
+        import datetime
+        from google.protobuf.struct_pb2 import Value
+
+        when = datetime.datetime(916, 2, 8, 0, 0, 0, tzinfo=datetime.timezone.utc)
+        value_pb = self._callFUT(when)
         self.assertIsInstance(value_pb, Value)
-        self.assertEqual(value_pb.string_value, datetime_helpers.to_rfc3339(now))
+        self.assertEqual(value_pb.string_value, "0916-02-08T00:00:00.000000Z")
 
     def test_w_timestamp_w_tz(self):
         import datetime
@@ -231,6 +260,16 @@ def test_w_timestamp_w_tz(self):
         self.assertIsInstance(value_pb, Value)
         self.assertEqual(value_pb.string_value, "2021-02-07T23:00:00.000000Z")
 
+    def test_w_timestamp_w_tz_pre1000ad(self):
+        import datetime
+        from google.protobuf.struct_pb2 import Value
+
+        zone = datetime.timezone(datetime.timedelta(hours=+1), name="CET")
+        when = datetime.datetime(721, 2, 8, 0, 0, 0, tzinfo=zone)
+        value_pb = self._callFUT(when)
+        self.assertIsInstance(value_pb, Value)
+        self.assertEqual(value_pb.string_value, "0721-02-07T23:00:00.000000Z")
+
     def test_w_unknown_type(self):
         with self.assertRaises(ValueError):
             self._callFUT(object())