Example of refactoring using rope library.

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

+import unittest
+
+from rope.contrib import finderrors
+from ropetest import testutils
+
+
+class FindErrorsTest(unittest.TestCase):
+
+    def setUp(self):
+        super(FindErrorsTest, self).setUp()
+        self.project = testutils.sample_project()
+        self.mod = self.project.root.create_file('mod.py')
+
+    def tearDown(self):
+        testutils.remove_project(self.project)
+        super(FindErrorsTest, self).tearDown()
+
+    def test_unresolved_variables(self):
+        self.mod.write('print(var)\n')
+        result = finderrors.find_errors(self.project, self.mod)
+        self.assertEquals(1, len(result))
+        self.assertEquals(1, result[0].lineno)
+
+    def test_defined_later(self):
+        self.mod.write('print(var)\nvar = 1\n')
+        result = finderrors.find_errors(self.project, self.mod)
+        self.assertEquals(1, len(result))
+        self.assertEquals(1, result[0].lineno)
+
+    def test_ignoring_builtins(self):
+        self.mod.write('range(2)\n')
+        result = finderrors.find_errors(self.project, self.mod)
+        self.assertEquals(0, len(result))
+
+    def test_ignoring_none(self):
+        self.mod.write('var = None\n')
+        result = finderrors.find_errors(self.project, self.mod)
+        self.assertEquals(0, len(result))
+
+    def test_bad_attributes(self):
+        code = 'class C(object):\n' \
+               '    pass\n' \
+               'c = C()\n' \
+               'print(c.var)\n'
+        self.mod.write(code)
+        result = finderrors.find_errors(self.project, self.mod)
+        self.assertEquals(1, len(result))
+        self.assertEquals(4, result[0].lineno)
+
+
+if __name__ == '__main__':
+    unittest.main()