- Reversing a change that was made in 0.9, the "singleton" nature

of the "constants" :func:`.null`, :func:`.true`, and :func:`.false`
has been reverted.   These functions returning a "singleton" object
had the effect that different instances would be treated as the
same regardless of lexical use, which in particular would impact
the rendering of the columns clause of a SELECT statement.
fixes #3170

1 files changed, 20 insertions, 1 deletions

diff --git a/test/sql/test_operators.py b/test/sql/test_operators.py
index 5c401845b..e8ad88511 100644
--- a/test/sql/test_operators.py
+++ b/test/sql/test_operators.py
@@ -1,4 +1,4 @@
-from sqlalchemy.testing import fixtures, eq_, is_
+from sqlalchemy.testing import fixtures, eq_, is_, is_not_
 from sqlalchemy import testing
 from sqlalchemy.testing import assert_raises_message
 from sqlalchemy.sql import column, desc, asc, literal, collate, null, true, false
@@ -778,6 +778,25 @@ class ConjunctionTest(fixtures.TestBase, testing.AssertsCompiledSQL):
             "SELECT x WHERE NOT NULL"
         )
 
+    def test_constant_non_singleton(self):
+        is_not_(null(), null())
+        is_not_(false(), false())
+        is_not_(true(), true())
+
+    def test_constant_render_distinct(self):
+        self.assert_compile(
+            select([null(), null()]),
+            "SELECT NULL AS anon_1, NULL AS anon_2"
+        )
+        self.assert_compile(
+            select([true(), true()]),
+            "SELECT true AS anon_1, true AS anon_2"
+        )
+        self.assert_compile(
+            select([false(), false()]),
+            "SELECT false AS anon_1, false AS anon_2"
+        )
+
 
 class OperatorPrecedenceTest(fixtures.TestBase, testing.AssertsCompiledSQL):
     __dialect__ = 'default'