1 files changed, 46 insertions, 0 deletions
diff --git a/pylint/test/unittest_checker_base.py b/pylint/test/unittest_checker_base.py
index f19544f..c68f379 100644
--- a/pylint/test/unittest_checker_base.py
+++ b/pylint/test/unittest_checker_base.py
@@ -246,6 +246,52 @@ class MultiNamingStyleTest(CheckerTestCase):
                 self.checker.visit_functiondef(func)
             self.checker.leave_module(func.root)
 
+class ComparisonTest(CheckerTestCase):
+    CHECKER_CLASS = base.ComparisonChecker
+
+    def test_singleton_comparison(self):
+        node = test_utils.extract_node("foo == True")
+        message = Message('singleton-comparison',
+                          node=node,
+                          args=(True, "just 'expr' or 'expr is True'"))
+        with self.assertAddsMessages(message):
+            self.checker.visit_compare(node)
+
+        node = test_utils.extract_node("foo == False")
+        message = Message('singleton-comparison',
+                          node=node,
+                          args=(False, "'not expr' or 'expr is False'"))
+        with self.assertAddsMessages(message):
+            self.checker.visit_compare(node)
+
+        node = test_utils.extract_node("foo == None")
+        message = Message('singleton-comparison',
+                          node=node,
+                          args=(None, "'expr is None'"))
+        with self.assertAddsMessages(message):
+            self.checker.visit_compare(node)
+
+        node = test_utils.extract_node("True == foo")
+        message = Message('singleton-comparison',
+                          node=node,
+                          args=(True, "just 'expr' or 'expr is True'"))
+        with self.assertAddsMessages(message):
+            self.checker.visit_compare(node)
+
+        node = test_utils.extract_node("False == foo")
+        message = Message('singleton-comparison',
+                          node=node,
+                          args=(False, "'not expr' or 'expr is False'"))
+        with self.assertAddsMessages(message):
+            self.checker.visit_compare(node)
+
+        node = test_utils.extract_node("None == foo")
+        message = Message('singleton-comparison',
+                          node=node,
+                          args=(None, "'expr is None'"))
+        with self.assertAddsMessages(message):
+            self.checker.visit_compare(node)
+
 
 if __name__ == '__main__':
     unittest.main()