Add tests for database limits of SmallIntegerField

Author: timgraham

tests/model_fields_/models.py

@@ -13,6 +13,11 @@
 from django_mongodb_backend.models import EmbeddedModel
 
 
+class UniqueIntegers(models.Model):
+    small = models.SmallIntegerField(unique=True, blank=True, null=True)
+    positive_small = models.PositiveSmallIntegerField(unique=True, blank=True, null=True)
+
+
 # ObjectIdField
 class ObjectIdModel(models.Model):
     field = ObjectIdField()

tests/model_fields_/test_integerfield.py

@@ -0,0 +1,49 @@
+from django.db import IntegrityError
+from django.test import TestCase
+
+from .models import UniqueIntegers
+
+
+class SmallIntegerFieldTests(TestCase):
+    max_value = 2**31 - 1
+    min_value = -(2**31)
+
+    def test_unique_max_value(self):
+        """
+        SmallIntegerField.db_type() is "int" which means unique constraints
+        are only enforced up to 32-bit values.
+        """
+        UniqueIntegers.objects.create(small=self.max_value + 1)
+        UniqueIntegers.objects.create(small=self.max_value + 1)  # no IntegrityError
+        UniqueIntegers.objects.create(small=self.max_value)
+        with self.assertRaises(IntegrityError):
+            UniqueIntegers.objects.create(small=self.max_value)
+
+    def test_unique_min_value(self):
+        """
+        SmallIntegerField.db_type() is "int" which means unique constraints
+        are only enforced down to negative 32-bit values.
+        """
+        UniqueIntegers.objects.create(small=self.min_value - 1)
+        UniqueIntegers.objects.create(small=self.min_value - 1)  # no IntegrityError
+        UniqueIntegers.objects.create(small=self.min_value)
+        with self.assertRaises(IntegrityError):
+            UniqueIntegers.objects.create(small=self.min_value)
+
+
+class PositiveSmallIntegerFieldTests(TestCase):
+    max_value = 2**31 - 1
+
+    def test_unique_max_value(self):
+        """
+        SmallIntegerField.db_type() is "int" which means unique constraints
+        are only enforced up to 32-bit values.
+        """
+        UniqueIntegers.objects.create(positive_small=self.max_value + 1)
+        UniqueIntegers.objects.create(positive_small=self.max_value + 1)  # no IntegrityError
+        UniqueIntegers.objects.create(positive_small=self.max_value)
+        with self.assertRaises(IntegrityError):
+            UniqueIntegers.objects.create(positive_small=self.max_value)
+
+    # test_unique_min_value isn't needed since PositiveSmallIntegerField has a
+    # limit of zero (enforced only in forms and model validation).