Example of refactoring using rope library.

tools/telemetry/third_party/rope/ropetest/contrib/changestacktest.py

+import unittest
+
+import rope.base.history
+import rope.contrib.changestack
+import rope.base.change
+from ropetest import testutils
+
+
+class ChangeStackTest(unittest.TestCase):
+
+    def setUp(self):
+        super(ChangeStackTest, self).setUp()
+        self.project = testutils.sample_project()
+
+    def tearDown(self):
+        testutils.remove_project(self.project)
+        super(ChangeStackTest, self).tearDown()
+
+    def test_change_stack(self):
+        myfile = self.project.root.create_file('myfile.txt')
+        myfile.write('1')
+        stack = rope.contrib.changestack.ChangeStack(self.project)
+        stack.push(rope.base.change.ChangeContents(myfile, '2'))
+        self.assertEquals('2', myfile.read())
+        stack.push(rope.base.change.ChangeContents(myfile, '3'))
+        self.assertEquals('3', myfile.read())
+        stack.pop_all()
+        self.assertEquals('1', myfile.read())
+        changes = stack.merged()
+        self.project.do(changes)
+        self.assertEquals('3', myfile.read())
+
+
+if __name__ == '__main__':
+    unittest.main()