Refs #28643 -- Added math database functions.

Thanks Nick Pope for much review.

tests/db_functions/math/test_ceil.py

@@ -0,0 +1,51 @@
+import math
+from decimal import Decimal
+
+from django.db.models import DecimalField
+from django.db.models.functions import Ceil
+from django.test import TestCase
+
+from ..models import DecimalModel, FloatModel, IntegerModel
+
+
+class CeilTests(TestCase):
+
+    def test_decimal(self):
+        DecimalModel.objects.create(n1=Decimal('12.9'), n2=Decimal('0.6'))
+        obj = DecimalModel.objects.annotate(n1_ceil=Ceil('n1'), n2_ceil=Ceil('n2')).first()
+        self.assertIsInstance(obj.n1_ceil, Decimal)
+        self.assertIsInstance(obj.n2_ceil, Decimal)
+        self.assertEqual(obj.n1_ceil, Decimal(math.ceil(obj.n1)))
+        self.assertEqual(obj.n2_ceil, Decimal(math.ceil(obj.n2)))
+
+    def test_float(self):
+        FloatModel.objects.create(f1=-12.5, f2=21.33)
+        obj = FloatModel.objects.annotate(f1_ceil=Ceil('f1'), f2_ceil=Ceil('f2')).first()
+        self.assertIsInstance(obj.f1_ceil, float)
+        self.assertIsInstance(obj.f2_ceil, float)
+        self.assertEqual(obj.f1_ceil, math.ceil(obj.f1))
+        self.assertEqual(obj.f2_ceil, math.ceil(obj.f2))
+
+    def test_integer(self):
+        IntegerModel.objects.create(small=-11, normal=0, big=-100)
+        obj = IntegerModel.objects.annotate(
+            small_ceil=Ceil('small'),
+            normal_ceil=Ceil('normal'),
+            big_ceil=Ceil('big'),
+        ).first()
+        self.assertIsInstance(obj.small_ceil, int)
+        self.assertIsInstance(obj.normal_ceil, int)
+        self.assertIsInstance(obj.big_ceil, int)
+        self.assertEqual(obj.small_ceil, math.ceil(obj.small))
+        self.assertEqual(obj.normal_ceil, math.ceil(obj.normal))
+        self.assertEqual(obj.big_ceil, math.ceil(obj.big))
+
+    def test_transform(self):
+        try:
+            DecimalField.register_lookup(Ceil)
+            DecimalModel.objects.create(n1=Decimal('3.12'), n2=Decimal('0'))
+            DecimalModel.objects.create(n1=Decimal('1.25'), n2=Decimal('0'))
+            objs = DecimalModel.objects.filter(n1__ceil__gt=3)
+            self.assertQuerysetEqual(objs, [Decimal('3.12')], lambda a: a.n1)
+        finally:
+            DecimalField._unregister_lookup(Ceil)