ChoiceType: non-None should not return None

sqlalchemy_utils/types/choice.py

@@ -214,10 +214,18 @@ class EnumTypeImpl(object):
         self.enum_class = enum_class
 
     def _coerce(self, value):
-        return self.enum_class(value) if value else None
+        if value is None:
+            return None
+        if value in self.enum_class:
+            return value
+        return self.enum_class(value)
 
     def process_bind_param(self, value, dialect):
-        return self.enum_class(value).value if value else None
+        if value is None:
+            return None
+        return self.enum_class(value).value
 
     def process_result_value(self, value, dialect):
-        return self.enum_class(value) if value else None
+        if value is None:
+            return None
+        return self.enum_class(value)

tests/types/test_choice.py

@@ -84,27 +84,33 @@ class TestChoiceTypeWithCustomUnderlyingType(TestCase):
 class TestEnumType(TestCase):
     def create_models(self):
         class OrderStatus(Enum):
-            unpaid = 1
-            paid = 2
+            unpaid = 0
+            paid = 1
 
         class Order(self.Base):
             __tablename__ = 'order'
             id_ = sa.Column(sa.Integer, primary_key=True)
             status = sa.Column(
                 ChoiceType(OrderStatus, impl=sa.Integer()),
-                default=OrderStatus.unpaid
+                default=OrderStatus.unpaid,
             )
 
             def __repr__(self):
                 return 'Order(%r, %r)' % (self.id_, self.status)
 
-            def pay(self):
-                self.status = OrderStatus.paid
+        class OrderNullable(self.Base):
+            __tablename__ = 'order_nullable'
+            id_ = sa.Column(sa.Integer, primary_key=True)
+            status = sa.Column(
+                ChoiceType(OrderStatus, impl=sa.Integer()),
+                nullable=True,
+            )
 
         self.OrderStatus = OrderStatus
         self.Order = Order
+        self.OrderNullable = OrderNullable
 
-    def test_parameter_processing(self):
+    def test_parameter_initialization(self):
         order = self.Order()
 
         self.session.add(order)
@@ -112,20 +118,64 @@ class TestEnumType(TestCase):
 
         order = self.session.query(self.Order).first()
         assert order.status is self.OrderStatus.unpaid
-        assert order.status.value == 1
+        assert order.status.value == 0
 
-        order.pay()
-        self.session.commit()
-
-        order = self.session.query(self.Order).first()
-        assert order.status is self.OrderStatus.paid
-        assert order.status.value == 2
-
-    def test_parameter_coercing(self):
+    def test_setting_by_value(self):
         order = self.Order()
-        order.status = 2
+        order.status = 1
 
         self.session.add(order)
         self.session.commit()
 
+        order = self.session.query(self.Order).first()
         assert order.status is self.OrderStatus.paid
+
+    def test_setting_by_enum(self):
+        order = self.Order()
+        order.status = self.OrderStatus.paid
+
+        self.session.add(order)
+        self.session.commit()
+
+        order = self.session.query(self.Order).first()
+        assert order.status is self.OrderStatus.paid
+
+    def test_setting_value_that_resolves_to_none(self):
+        order = self.Order()
+        order.status = 0
+
+        self.session.add(order)
+        self.session.commit()
+
+        order = self.session.query(self.Order).first()
+        assert order.status is self.OrderStatus.unpaid
+
+    def test_setting_to_wrong_enum_raises_valueerror(self):
+        class WrongEnum(Enum):
+            foo = 0
+            bar = 1
+
+        order = self.Order()
+
+        with raises(ValueError):
+            order.status = WrongEnum.foo
+
+    def test_setting_to_uncoerceable_type_raises_valueerror(self):
+        order = self.Order()
+        with raises(ValueError):
+            order.status = 'Bad value'
+
+    def test_order_nullable_stores_none(self):
+        # With nullable=False as in `Order`, a `None` value is always
+        # converted to the default value, unless we explicitly set it to
+        # sqlalchemy.sql.null(), so we use this class to test our ability
+        # to set and retrive `None`.
+        order_nullable = self.OrderNullable()
+        assert order_nullable.status is None
+
+        order_nullable.status = None
+
+        self.session.add(order_nullable)
+        self.session.commit()
+
+        assert order_nullable.status is None