More tests for range coercion

sqlalchemy_utils/types/range.py

@@ -36,12 +36,18 @@ class RangeComparator(types.TypeEngine.Comparator):
     @classmethod
     def coerce_arg(cls, func):
         def operation(self, other, **kwargs):
-            if other is None:
+            coerced_types = (
-                return getattr(types.TypeEngine.Comparator, func)(
+                self.type.interval_class.type,
-                    self, other, **kwargs
+                tuple,
-                )
+                list,
+                str,
+                unicode
+            )
+
+            if isinstance(other, coerced_types):
+                other = self.type.interval_class(other)
             return getattr(types.TypeEngine.Comparator, func)(
-                self, self.type.interval_class(other), **kwargs
+                self, other, **kwargs
             )
         return operation
 
@@ -144,6 +150,10 @@ class IntRangeType(RangeType):
         )
         print total
         # '30-140'
+
+    Good reading:
+
+    http://wiki.postgresql.org/images/f/f0/Range-types.pdf
     """
 
     impl = INT4RANGE

tests/types/test_int_range.py

@@ -98,6 +98,18 @@ class TestIntRangeTypeOnPostgres(NumberRangeTestCase):
         )
         assert query.count()
 
+    def test_eq_with_query_arg(self):
+        self.create_building([1, 3])
+        query = (
+            self.session.query(self.Building)
+            .filter(
+                self.Building.persons_at_night ==
+                self.session.query(
+                    self.Building.persons_at_night)
+                ).order_by(self.Building.persons_at_night).limit(1)
+        )
+        assert query.count()
+
     @mark.parametrize(
         'number_range',
         (