diff -r b0883c15b28c Lib/test/test_pep292.py
--- a/Lib/test/test_pep292.py	Mon Mar 07 18:14:36 2011 +0000
+++ b/Lib/test/test_pep292.py	Mon Mar 14 15:23:23 2011 -0400
@@ -42,6 +42,19 @@
         s = Template('$who likes $$')
         eq(s.substitute(dict(who='tim', what='ham')), 'tim likes $')
 
+    def test_invalid(self):
+        class MyPattern(Template):
+            pattern = r"""
+            (?:
+            (?P<invalid>)            |
+            (?P<escaped>%(delim)s)   |
+            @(?P<named>%(id)s)       |
+            @{(?P<braced>%(id)s)}    
+            )
+            """
+        s = MyPattern('$')
+        self.assertRaises(ValueError, s.substitute, dict()) 
+
     def test_percents(self):
         eq = self.assertEqual
         s = Template('%(foo)s $foo ${foo}')
diff -r b0883c15b28c Lib/test/test_string.py
--- a/Lib/test/test_string.py	Mon Mar 07 18:14:36 2011 +0000
+++ b/Lib/test/test_string.py	Mon Mar 14 15:23:23 2011 -0400
@@ -112,6 +112,30 @@
         self.assertRaises(ValueError, fmt.format, "{0}", 10, 20, i=100)
         self.assertRaises(ValueError, fmt.format, "{i}", 10, 20, i=100)
 
+    def test_vformat_assert(self):
+        cls = string.Formatter()
+        kwargs = {
+            "i": 100
+        }
+        self.assertRaises(ValueError, cls._vformat,
+                cls.format, "{0}", kwargs, set(), -2)
+
+    def test_convert_field(self):
+        cls = string.Formatter()
+        self.assertEqual(cls.format("{0!s}", 'foo'), 'foo')
+        self.assertRaises(ValueError, cls.format, "{0!h}", 'foo')
+
+    def test_get_field(self):
+        cls = string.Formatter()
+        class MyClass:
+            name = 'lumberjack'
+        x = MyClass()
+        self.assertEqual(cls.format("{0.name}", x), 'lumberjack')
+
+        lookup = ["eggs", "and", "spam"]
+        self.assertEqual(cls.format("{0[2]}", lookup), 'spam')
+
+
 def test_main():
     support.run_unittest(ModuleTest)