Use " if __name__ == "__main__": " idioms in your scripts and encapsulate all the functional functions in the functions.
Then you can import your scripts into another script (for example, unit test script) without having its body executed. This will allow you to write unit tests for functionality and run them through the nose .
I recommend storing the "main" block in a row or two.
For instance:
plus_one.py
#!/usr/bin/env python import sys def main(args): try: output(plus_one(get_number(args))) except (IndexError, ValueError), e: print e return 1 return 0 def get_number(args): return int(args[1]) def plus_one(number): return number + 1 def output(some_text): print some_text if __name__ == '__main__': sys.exit(main(sys.argv))
You can check command line parameters, output, exceptions and return codes in your unittests ...
t_plus_one.py
#!/usr/bin/env python from StringIO import StringIO import plus_one import unittest class TestPlusOne(unittest.TestCase): def test_main_returns_zero_on_success(self): self.assertEquals(plus_one.main(['test', '1']), 0) def test_main_returns_nonzero_on_error(self): self.assertNotEqual(plus_one.main(['test']), 0) def test_get_number_returns_second_list_element_as_integer(self): self.assertEquals(plus_one.get_number(['anything', 42]), 42) def test_get_number_raises_value_error_with_string(self): self.assertRaises(ValueError, plus_one.get_number, ['something', 'forty-two']) def test_get_number_raises_index_error_with_too_few_arguments(self): self.assertRaises(IndexError, plus_one.get_number, ['nothing']) def test_plus_one_adds_one_to_number(self): self.assertEquals(plus_one.plus_one(1), 2) def test_output_prints_input(self): saved_stdout, plus_one.sys.stdout = plus_one.sys.stdout, StringIO('_') plus_one.output('some_text') self.assertEquals(plus_one.sys.stdout.getvalue(), 'some_text\n') plus_one.sys.stdout = saved_stdout if __name__ == '__main__': unittest.main()
Output
python plus_one.py 41
42
nosetests -v t_plus_one.py
test_get_number_raises_index_error_with_too_few_arguments (t_plus_one.TestPlusOne) ... ok test_get_number_raises_value_error_with_string (t_plus_one.TestPlusOne) ... ok test_get_number_returns_second_list_element_as_integer (t_plus_one.TestPlusOne) ... ok test_main_returns_nonzero_on_error (t_plus_one.TestPlusOne) ... ok test_main_returns_zero_on_success (t_plus_one.TestPlusOne) ... ok test_output_prints_input (t_plus_one.TestPlusOne) ... ok test_plus_one_adds_one_to_number (t_plus_one.TestPlusOne) ... ok ---------------------------------------------------------------------- Ran 7 tests in 0.002s OK