1 files changed, 11 insertions, 0 deletions
diff --git a/Lib/test/test_unicode.py b/Lib/test/test_unicode.py
index a859c0f..973a008 100644
--- a/Lib/test/test_unicode.py
+++ b/Lib/test/test_unicode.py
@@ -1193,6 +1193,17 @@ class UnicodeTest(
         self.assertRaises(MemoryError, alloc)
         self.assertRaises(MemoryError, alloc)
 
+    def test_format_subclass(self):
+        class U(unicode):
+            def __str__(self):
+                return '__str__ overridden'
+            def __unicode__(self):
+                return u'__unicode__ overridden'
+        u = U(u'xxx')
+        self.assertEquals("%s" % u, u'__unicode__ overridden')
+        self.assertEquals("{}".format(u), u'__unicode__ overridden')
+
+
 def test_main():
     test_support.run_unittest(__name__)