Fixed #28926 -- Fixed loss of precision of big DurationField values on SQLite and MySQL.

3 files changed, 37 insertions, 2 deletions

diff --git a/tests/expressions/tests.py b/tests/expressions/tests.py
index 5d54e46c02..2a6714a65f 100644
--- a/tests/expressions/tests.py
+++ b/tests/expressions/tests.py
@@ -1250,6 +1250,16 @@ class FTimeDeltaTests(TestCase):
         ]
         self.assertEqual(over_estimate, ['e4'])
 
+    @skipUnlessDBFeature('supports_temporal_subtraction')
+    def test_datetime_subtraction_microseconds(self):
+        delta = datetime.timedelta(microseconds=8999999999999999)
+        Experiment.objects.update(end=F('start') + delta)
+        qs = Experiment.objects.annotate(
+            delta=ExpressionWrapper(F('end') - F('start'), output_field=models.DurationField())
+        )
+        for e in qs:
+            self.assertEqual(e.delta, delta)
+
     def test_duration_with_datetime(self):
         # Exclude e1 which has very high precision so we can test this on all
         # backends regardless of whether or not it supports
@@ -1259,6 +1269,15 @@ class FTimeDeltaTests(TestCase):
         ).order_by('name')
         self.assertQuerysetEqual(over_estimate, ['e3', 'e4', 'e5'], lambda e: e.name)
 
+    def test_duration_with_datetime_microseconds(self):
+        delta = datetime.timedelta(microseconds=8999999999999999)
+        qs = Experiment.objects.annotate(dt=ExpressionWrapper(
+            F('start') + delta,
+            output_field=models.DateTimeField(),
+        ))
+        for e in qs:
+            self.assertEqual(e.dt, e.start + delta)
+
     def test_date_minus_duration(self):
         more_than_4_days = Experiment.objects.filter(
             assigned__lt=F('completed') - Value(datetime.timedelta(days=4), output_field=models.DurationField())
diff --git a/tests/model_fields/test_durationfield.py b/tests/model_fields/test_durationfield.py
index d39126a0ab..b73994f86a 100644
--- a/tests/model_fields/test_durationfield.py
+++ b/tests/model_fields/test_durationfield.py
@@ -12,7 +12,7 @@ from .models import DurationModel, NullDurationModel
 class TestSaveLoad(TestCase):
 
     def test_simple_roundtrip(self):
-        duration = datetime.timedelta(days=123, seconds=123, microseconds=123)
+        duration = datetime.timedelta(microseconds=8999999999999999)
         DurationModel.objects.create(field=duration)
         loaded = DurationModel.objects.get()
         self.assertEqual(loaded.field, duration)
diff --git a/tests/utils_tests/test_duration.py b/tests/utils_tests/test_duration.py
index d0564f396f..84a3a0893f 100644
--- a/tests/utils_tests/test_duration.py
+++ b/tests/utils_tests/test_duration.py
@@ -2,7 +2,9 @@ import datetime
 import unittest
 
 from django.utils.dateparse import parse_duration
-from django.utils.duration import duration_iso_string, duration_string
+from django.utils.duration import (
+    duration_iso_string, duration_microseconds, duration_string,
+)
 
 
 class TestDurationString(unittest.TestCase):
@@ -79,3 +81,17 @@ class TestParseISODurationRoundtrip(unittest.TestCase):
     def test_negative(self):
         duration = datetime.timedelta(days=-1, hours=1, minutes=3, seconds=5)
         self.assertEqual(parse_duration(duration_iso_string(duration)).total_seconds(), duration.total_seconds())
+
+
+class TestDurationMicroseconds(unittest.TestCase):
+    def test(self):
+        deltas = [
+            datetime.timedelta.max,
+            datetime.timedelta.min,
+            datetime.timedelta.resolution,
+            -datetime.timedelta.resolution,
+            datetime.timedelta(microseconds=8999999999999999),
+        ]
+        for delta in deltas:
+            with self.subTest(delta=delta):
+                self.assertEqual(datetime.timedelta(microseconds=duration_microseconds(delta)), delta)