Add assert_min_value and assert_max_value funcs

docs/testing.rst

@@ -4,6 +4,21 @@ Testing
 .. automodule:: sqlalchemy_utils.asserts
 
 
+assert_min_value
+----------------
+
+.. autofunction:: assert_min_value
+
+assert_max_length
+-----------------
+
+.. autofunction:: assert_max_length
+
+assert_max_value
+----------------
+
+.. autofunction:: assert_max_value
+
 assert_nullable
 ---------------
 
@@ -13,8 +28,3 @@ assert_non_nullable
 -------------------
 
 .. autofunction:: assert_non_nullable
-
-assert_max_length
------------------
-
-.. autofunction:: assert_max_length

sqlalchemy_utils/__init__.py

@@ -1,5 +1,11 @@
 from .aggregates import aggregated
-from .asserts import assert_nullable, assert_non_nullable, assert_max_length
+from .asserts import (
+    assert_min_value,
+    assert_max_length,
+    assert_max_value,
+    assert_nullable,
+    assert_non_nullable
+)
 from .batch import batch_fetch, with_backrefs
 from .decorators import generates
 from .exceptions import ImproperlyConfigured

sqlalchemy_utils/asserts.py

@@ -44,9 +44,7 @@ class raises(object):
         return self
 
     def __exit__(self, exc_type, exc_val, exc_tb):
-        if exc_type != self.expected_exc:
-            return False
-        return True
+        return exc_type == self.expected_exc
 
 
 def _update_field(obj, field, value):
@@ -101,6 +99,31 @@ def assert_max_length(obj, column, max_length):
 
     :param obj: SQLAlchemy declarative model object
     :param column: Name of the column
+    :param max_length: Maximum length of given column
     """
     _expect_successful_update(obj, column, u'a' * max_length, DataError)
     _expect_failing_update(obj, column, u'a' * (max_length + 1), DataError)
+
+
+def assert_min_value(obj, column, min_value):
+    """
+    Assert that the given column must have a minimum value of `min_value`.
+
+    :param obj: SQLAlchemy declarative model object
+    :param column: Name of the column
+    :param min_value: The minimum allowed value for given column
+    """
+    _expect_successful_update(obj, column, min_value, IntegrityError)
+    _expect_failing_update(obj, column, min_value - 1, IntegrityError)
+
+
+def assert_max_value(obj, column, min_value):
+    """
+    Assert that the given column must have a minimum value of `max_value`.
+
+    :param obj: SQLAlchemy declarative model object
+    :param column: Name of the column
+    :param max_value: The maximum allowed value for given column
+    """
+    _expect_successful_update(obj, column, min_value, IntegrityError)
+    _expect_failing_update(obj, column, min_value + 1, IntegrityError)

sqlalchemy_utils/listeners.py

@@ -113,7 +113,8 @@ def auto_delete_orphans(attr):
     """
     Delete orphans for given SQLAlchemy model attribute. This function can be
     used for deleting many-to-many associated orphans easily. For more
-    information see https://bitbucket.org/zzzeek/sqlalchemy/wiki/UsageRecipes/ManyToManyOrphan.
+    information see
+    https://bitbucket.org/zzzeek/sqlalchemy/wiki/UsageRecipes/ManyToManyOrphan.
 
     Consider the following model definition:
 

tests/test_asserts.py

@@ -1,9 +1,11 @@
 import sqlalchemy as sa
 import pytest
 from sqlalchemy_utils import (
+    assert_min_value,
+    assert_max_length,
+    assert_max_value,
     assert_nullable,
-    assert_non_nullable,
-    assert_max_length
+    assert_non_nullable
 )
 from sqlalchemy_utils.asserts import raises
 
@@ -33,6 +35,10 @@ class AssertionTestCase(TestCase):
             age = sa.Column(sa.Integer, nullable=False)
             email = sa.Column(sa.String(200), nullable=False, unique=True)
 
+            __table_args__ = (
+                sa.CheckConstraint(sa.and_(age >= 0, age <= 150)),
+            )
+
         self.User = User
 
     def setup_method(self, method):
@@ -88,3 +94,39 @@ class TestAssertMaxLength(AssertionTestCase):
             assert_max_length(self.user, 'name', 21)
         with raises(AssertionError):
             assert_max_length(self.user, 'name', 21)
+
+
+class TestAssertMinValue(AssertionTestCase):
+    def test_with_min_value(self):
+        assert_min_value(self.user, 'age', 0)
+        assert_min_value(self.user, 'age', 0)
+
+    def test_smaller_than_min_value(self):
+        with raises(AssertionError):
+            assert_min_value(self.user, 'age', -1)
+        with raises(AssertionError):
+            assert_min_value(self.user, 'age', -1)
+
+    def test_bigger_than_min_value(self):
+        with raises(AssertionError):
+            assert_min_value(self.user, 'age', 1)
+        with raises(AssertionError):
+            assert_min_value(self.user, 'age', 1)
+
+
+class TestAssertMaxValue(AssertionTestCase):
+    def test_with_min_value(self):
+        assert_max_value(self.user, 'age', 150)
+        assert_max_value(self.user, 'age', 150)
+
+    def test_smaller_than_max_value(self):
+        with raises(AssertionError):
+            assert_max_value(self.user, 'age', 149)
+        with raises(AssertionError):
+            assert_max_value(self.user, 'age', 149)
+
+    def test_bigger_than_max_value(self):
+        with raises(AssertionError):
+            assert_max_value(self.user, 'age', 151)
+        with raises(AssertionError):
+            assert_max_value(self.user, 'age', 151)