diff -r 54d7e9919876 Lib/test/test_string.py
--- a/Lib/test/test_string.py	Thu Mar 24 13:55:58 2016 +0100
+++ b/Lib/test/test_string.py	Thu Jun 02 10:23:08 2016 -0700
@@ -186,6 +186,29 @@
             fmt._vformat("{i}", args, kwargs, set(), -1)
         self.assertIn("recursion", str(err.exception))
 
+    def test_basic_template_convert(self):
+        template = string.Template('The $animal says $sound')
+        sub = template.substitute(animal='duck', sound='quack')
+        self.assertEqual(sub, "The duck says quack")
+
+    def test_invalid_args_for_substitution(self):
+        template = string.Template('The $animal says $sound')
+        self.assertRaises(TypeError, template.substitute, 'chicken', 'cluck')
+        self.assertRaises(TypeError, template.substitute, None)
+
+    def test_invalid_placeholder_throws_value_error(self):
+        template = string.Template('The $thing costs $100')
+        self.assertRaises(ValueError, template.substitute, thing='chair')
+
+    def test_placeholders_from_kws_take_precedence(self):
+        template = string.Template('The $animal says $sound')
+        mapping = {'animal': 'dog', 'sound': 'ruf'}
+        substitution = template.substitute(mapping, animal='cat', sound='meow')
+        self.assertEqual(substitution, 'The cat says meow')
+
+    def test_safe_substitute(self):
+        template = string.Template('The $animal says $sound')
+        self.assertEqual(template.safe_substitute(animal='cow'), 'The cow says $sound')
 
 if __name__ == "__main__":
     unittest.main()