fixed rounding error for DateTime and Time (#412)

Author: martin-neotech

neo4j/time/__init__.py

@@ -23,15 +23,42 @@
 a number of utility functions.
 """
 
-from datetime import timedelta, date, time, datetime
+from datetime import (
+    timedelta,
+    date,
+    time,
+    datetime,
+)
 from functools import total_ordering
 from re import compile as re_compile
-from time import gmtime, mktime, struct_time
-
-from neo4j.time.arithmetic import (nano_add, nano_sub, nano_mul, nano_div,
-                                   nano_mod, nano_divmod,
-                                   symmetric_divmod, round_half_to_even)
-from neo4j.time.metaclasses import DateType, TimeType, DateTimeType
+from time import (
+    gmtime,
+    mktime,
+    struct_time,
+)
+from decimal import Decimal
+
+from neo4j.time.arithmetic import (
+    nano_add,
+    nano_sub,
+    nano_mul,
+    nano_div,
+    nano_mod,
+    nano_divmod,
+    symmetric_divmod,
+    round_half_to_even,
+)
+from neo4j.time.metaclasses import (
+    DateType,
+    TimeType,
+    DateTimeType,
+)
+
+import logging
+from neo4j.debug import watch
+watch("neo4j")
+
+log = logging.getLogger("neo4j")
 
 
 MIN_INT64 = -(2 ** 63)
@@ -49,6 +76,8 @@
 DURATION_ISO_PATTERN = re_compile(r"^P((\d+)Y)?((\d+)M)?((\d+)D)?"
                                   r"(T((\d+)H)?((\d+)M)?((\d+(\.\d+)?)?S)?)?$")
 
+NANO_SECONDS = 1000000000
+
 
 def _is_leap_year(year):
     if year % 4 != 0:
@@ -1118,8 +1147,9 @@ def tzname(self):
         return self.tzinfo.tzname(self)
 
     def to_clock_time(self):
-        seconds, nanoseconds = nano_divmod(self.ticks, 1)
-        return ClockTime(seconds, 1000000000 * nanoseconds)
+        seconds, nanoseconds = nano_divmod(self.ticks, 1)  # int, float
+        nanoseconds_int = int(Decimal(str(nanoseconds)) * NANO_SECONDS)  # Convert fractions to an integer without losing precision
+        return ClockTime(seconds, nanoseconds_int)
 
     def to_native(self):
         """ Convert to a native Python `datetime.time` value.
@@ -1437,8 +1467,9 @@ def to_clock_time(self):
         for month in range(1, self.month):
             total_seconds += 86400 * Date.days_in_month(self.year, month)
         total_seconds += 86400 * (self.day - 1)
-        seconds, nanoseconds = nano_divmod(self.__time.ticks, 1)
-        return ClockTime(total_seconds + seconds, 1000000000 * nanoseconds)
+        seconds, nanoseconds = nano_divmod(self.__time.ticks, 1)  # int, float
+        nanoseconds_int = int(Decimal(str(nanoseconds)) * NANO_SECONDS)  # Convert fractions to an integer without losing precision
+        return ClockTime(total_seconds + seconds, nanoseconds_int)
 
     def to_native(self):
         """ Convert to a native Python `datetime.datetime` value.

neo4j/time/hydration.py

@@ -142,7 +142,9 @@ def seconds_and_nanoseconds(dt):
         if isinstance(dt, datetime):
             dt = DateTime.from_native(dt)
         zone_epoch = DateTime(1970, 1, 1, tzinfo=dt.tzinfo)
-        t = dt.to_clock_time() - zone_epoch.to_clock_time()
+        dt_clock_time = dt.to_clock_time()
+        zone_epoch_clock_time = zone_epoch.to_clock_time()
+        t = dt_clock_time - zone_epoch_clock_time
         return t.seconds, t.nanoseconds
 
     tz = value.tzinfo

tests/integration/test_temporal_types.py

@@ -20,6 +20,8 @@
 
 
 import pytest
+import datetime
+
 from pytz import (
     FixedOffset,
     timezone,
@@ -330,3 +332,74 @@ def test_nanosecond_resolution_duration_output(cypher_eval):
     assert isinstance(value, Duration)
     assert value == Duration(years=1, months=2, days=3, hours=4,
                              minutes=5, seconds=6.789123456)
+
+
+def test_datetime_parameter_case1(session):
+    # python -m pytest tests/integration/test_temporal_types.py -s -v -k test_datetime_parameter_case1
+    dt1 = session.run("RETURN datetime('2019-10-30T07:54:02.129790001+00:00')").single().value()
+    assert isinstance(dt1, DateTime)
+
+    dt2 = session.run("RETURN $date_time", date_time=dt1).single().value()
+    assert isinstance(dt2, DateTime)
+
+    assert dt1 == dt2
+
+
+def test_datetime_parameter_case2(session):
+    # python -m pytest tests/integration/test_temporal_types.py -s -v -k test_datetime_parameter_case2
+    dt1 = session.run("RETURN datetime('2019-10-30T07:54:02.129790999[UTC]')").single().value()
+    assert isinstance(dt1, DateTime)
+    assert dt1.iso_format() == "2019-10-30T07:54:02.129790999+00:00"
+
+    dt2 = session.run("RETURN $date_time", date_time=dt1).single().value()
+    assert isinstance(dt2, DateTime)
+
+    assert dt1 == dt2
+
+
+def test_datetime_parameter_case3(session):
+    # python -m pytest tests/integration/test_temporal_types.py -s -v -k test_datetime_parameter_case1
+    dt1 = session.run("RETURN datetime('2019-10-30T07:54:02.129790+00:00')").single().value()
+    assert isinstance(dt1, DateTime)
+
+    dt2 = session.run("RETURN $date_time", date_time=dt1).single().value()
+    assert isinstance(dt2, DateTime)
+
+    assert dt1 == dt2
+
+
+def test_time_parameter_case1(session):
+    # python -m pytest tests/integration/test_temporal_types.py -s -v -k test_time_parameter_case1
+    t1 = session.run("RETURN time('07:54:02.129790001+00:00')").single().value()
+    assert isinstance(t1, Time)
+
+    t2 = session.run("RETURN $time", time=t1).single().value()
+    assert isinstance(t2, Time)
+
+    assert t1 == t2
+
+
+def test_time_parameter_case2(session):
+    # python -m pytest tests/integration/test_temporal_types.py -s -v -k test_time_parameter_case2
+    t1 = session.run("RETURN time('07:54:02.129790999+00:00')").single().value()
+    assert isinstance(t1, Time)
+    # assert t1.iso_format() == "07:54:02.129790999+00:00"  # TODO: Broken, does not show time_zone_delta +00:00
+    time_zone_delta = t1.utc_offset()
+    assert isinstance(time_zone_delta, datetime.timedelta)
+    assert time_zone_delta == datetime.timedelta(0)
+
+    t2 = session.run("RETURN $time", time=t1).single().value()
+    assert isinstance(t2, Time)
+
+    assert t1 == t2
+
+
+def test_time_parameter_case3(session):
+    # python -m pytest tests/integration/test_temporal_types.py -s -v -k test_time_parameter_case3
+    t1 = session.run("RETURN time('07:54:02.129790+00:00')").single().value()
+    assert isinstance(t1, Time)
+
+    t2 = session.run("RETURN $time", time=t1).single().value()
+    assert isinstance(t2, Time)
+
+    assert t1 == t2

tests/unit/time/test_datetime.py

@@ -19,17 +19,44 @@
 # limitations under the License.
 
 
-from datetime import datetime, timedelta
 from unittest import TestCase
-
-from pytz import timezone, FixedOffset
-
-from neo4j.time import DateTime, MIN_YEAR, MAX_YEAR, Duration
-from neo4j.time.arithmetic import nano_add, nano_div
-from neo4j.time.clock_implementations import Clock, ClockTime
-
-
-eastern = timezone("US/Eastern")
+from datetime import (
+    datetime,
+    timedelta,
+)
+from pytz import (
+    timezone,
+    FixedOffset,
+)
+
+from neo4j.time import (
+    DateTime,
+    MIN_YEAR,
+    MAX_YEAR,
+    Duration,
+)
+from neo4j.time.arithmetic import (
+    nano_add,
+    nano_div,
+)
+from neo4j.time.clock_implementations import (
+    Clock,
+    ClockTime,
+)
+from neo4j.time.hydration import (
+    hydrate_date,
+    dehydrate_date,
+    hydrate_time,
+    dehydrate_time,
+    hydrate_datetime,
+    dehydrate_datetime,
+    hydrate_duration,
+    dehydrate_duration,
+    dehydrate_timedelta,
+)
+
+timezone_us_eastern = timezone("US/Eastern")
+timezone_utc = timezone("UTC")
 
 
 class FixedClock(Clock):
@@ -132,7 +159,7 @@ def test_now_without_tz(self):
         self.assertIsNone(t.tzinfo)
 
     def test_now_with_tz(self):
-        t = DateTime.now(eastern)
+        t = DateTime.now(timezone_us_eastern)
         self.assertEqual(t.year, 1970)
         self.assertEqual(t.month, 1)
         self.assertEqual(t.day, 1)
@@ -168,7 +195,7 @@ def test_from_overflowing_timestamp(self):
             _ = DateTime.from_timestamp(999999999999999999)
 
     def test_from_timestamp_with_tz(self):
-        t = DateTime.from_timestamp(0, eastern)
+        t = DateTime.from_timestamp(0, timezone_us_eastern)
         self.assertEqual(t.year, 1969)
         self.assertEqual(t.month, 12)
         self.assertEqual(t.day, 31)
@@ -215,13 +242,13 @@ def test_subtract_native_datetime_2(self):
         self.assertEqual(t, timedelta(days=65, hours=23, seconds=17.914390409))
 
     def test_normalization(self):
-        ndt1 = eastern.normalize(DateTime(2018, 4, 27, 23, 0, 17, tzinfo=eastern))
-        ndt2 = eastern.normalize(datetime(2018, 4, 27, 23, 0, 17, tzinfo=eastern))
+        ndt1 = timezone_us_eastern.normalize(DateTime(2018, 4, 27, 23, 0, 17, tzinfo=timezone_us_eastern))
+        ndt2 = timezone_us_eastern.normalize(datetime(2018, 4, 27, 23, 0, 17, tzinfo=timezone_us_eastern))
         self.assertEqual(ndt1, ndt2)
 
     def test_localization(self):
-        ldt1 = eastern.localize(datetime(2018, 4, 27, 23, 0, 17))
-        ldt2 = eastern.localize(DateTime(2018, 4, 27, 23, 0, 17))
+        ldt1 = timezone_us_eastern.localize(datetime(2018, 4, 27, 23, 0, 17))
+        ldt2 = timezone_us_eastern.localize(DateTime(2018, 4, 27, 23, 0, 17))
         self.assertEqual(ldt1, ldt2)
 
     def test_from_native(self):
@@ -253,11 +280,11 @@ def test_iso_format_with_trailing_zeroes(self):
         self.assertEqual("2018-10-01T12:34:56.789000000", dt.iso_format())
 
     def test_iso_format_with_tz(self):
-        dt = eastern.localize(DateTime(2018, 10, 1, 12, 34, 56.789123456))
+        dt = timezone_us_eastern.localize(DateTime(2018, 10, 1, 12, 34, 56.789123456))
         self.assertEqual("2018-10-01T12:34:56.789123456-04:00", dt.iso_format())
 
     def test_iso_format_with_tz_and_trailing_zeroes(self):
-        dt = eastern.localize(DateTime(2018, 10, 1, 12, 34, 56.789))
+        dt = timezone_us_eastern.localize(DateTime(2018, 10, 1, 12, 34, 56.789))
         self.assertEqual("2018-10-01T12:34:56.789000000-04:00", dt.iso_format())
 
     def test_from_iso_format_hour_only(self):
@@ -309,3 +336,12 @@ def test_from_iso_format_with_negative_long_tz(self):
         expected = DateTime(2018, 10, 1, 12, 34, 56.123456789, tzinfo=FixedOffset(-754))
         actual = DateTime.from_iso_format("2018-10-01T12:34:56.123456789-12:34:56.123456")
         self.assertEqual(expected, actual)
+
+
+def test_potential_rounding_error():
+    # python -m pytest tests/unit/time/test_datetime.py -s -v -k test_potential_rounding_error
+    expected = DateTime(2019, 10, 30, 7, 54, 2.129790999, tzinfo=timezone_utc)
+    assert expected.iso_format() == "2019-10-30T07:54:02.129790999+00:00"
+
+    actual = DateTime.from_iso_format("2019-10-30T07:54:02.129790999+00:00")
+    assert expected == actual