remove backported unittest methods (#705)

Author: asottile

pyflakes/test/harness.py

@@ -35,38 +35,3 @@ def flakes(self, input, *expectedOutputs, **kw):
 but got:
 %s''' % (input, expectedOutputs, '\n'.join([str(o) for o in w.messages])))
         return w
-
-    if not hasattr(unittest.TestCase, 'assertIs'):
-
-        def assertIs(self, expr1, expr2, msg=None):
-            if expr1 is not expr2:
-                self.fail(msg or '%r is not %r' % (expr1, expr2))
-
-    if not hasattr(unittest.TestCase, 'assertIsInstance'):
-
-        def assertIsInstance(self, obj, cls, msg=None):
-            """Same as self.assertTrue(isinstance(obj, cls))."""
-            if not isinstance(obj, cls):
-                self.fail(msg or '%r is not an instance of %r' % (obj, cls))
-
-    if not hasattr(unittest.TestCase, 'assertNotIsInstance'):
-
-        def assertNotIsInstance(self, obj, cls, msg=None):
-            """Same as self.assertFalse(isinstance(obj, cls))."""
-            if isinstance(obj, cls):
-                self.fail(msg or '%r is an instance of %r' % (obj, cls))
-
-    if not hasattr(unittest.TestCase, 'assertIn'):
-
-        def assertIn(self, member, container, msg=None):
-            """Just like self.assertTrue(a in b)."""
-            if member not in container:
-                self.fail(msg or '%r not found in %r' % (member, container))
-
-    if not hasattr(unittest.TestCase, 'assertNotIn'):
-
-        def assertNotIn(self, member, container, msg=None):
-            """Just like self.assertTrue(a not in b)."""
-            if member in container:
-                self.fail(msg or
-                          '%r unexpectedly found in %r' % (member, container))