Fix query without order by handling

CHANGES.rst

@@ -8,6 +8,7 @@ Here you can see the full list of changes between each SQLAlchemy-Utils release.
 ^^^^^^^^^^^^^^^^^^^
 
 - Made assert_* functions automatically rollback session
+- Changed make_order_by_deterministic attach order by primary key for queries without order by
 - Fixed alias handling in has_unique_index
 - Fixed alias handling in has_index
 - Fixed alias handling in make_order_by_deterministic

sqlalchemy_utils/functions/sort_query.py

@@ -169,19 +169,20 @@ def make_order_by_deterministic(query):
 
     .. versionadded: 0.27.1
     """
-    if not query._order_by:
-        return query
+    order_by_func = sa.asc
 
-    order_by = query._order_by[0]
-    if isinstance(order_by, sa.sql.expression.UnaryExpression):
-        if order_by.modifier == sa.sql.operators.desc_op:
-            order_by_func = sa.desc
-        else:
-            order_by_func = sa.asc
-        column = order_by.get_children()[0]
+    if not query._order_by:
+        column = None
     else:
-        column = order_by
-        order_by_func = sa.asc
+        order_by = query._order_by[0]
+        if isinstance(order_by, sa.sql.expression.UnaryExpression):
+            if order_by.modifier == sa.sql.operators.desc_op:
+                order_by_func = sa.desc
+            else:
+                order_by_func = sa.asc
+            column = order_by.get_children()[0]
+        else:
+            column = order_by
 
     # Queries that are ordered by an already
     if isinstance(column, sa.Column):

tests/functions/test_make_order_by_deterministic.py

@@ -82,7 +82,7 @@ class TestMakeOrderByDeterministic(TestCase):
     def test_query_without_order_by(self):
         query = self.session.query(self.User)
         query = make_order_by_deterministic(query)
-        assert 'ORDER BY' not in str(query)
+        assert 'ORDER BY "user".id' in str(query)
 
     def test_alias(self):
         alias = sa.orm.aliased(self.User.__table__)