unittest learning

Basic example

import unittest

class TestStringMethods(unittest.TestCase):

    def test_upper(self):
        self.assertEqual('foo'.upper(), 'FOO')

    def test_isupper(self):
        self.assertTrue('FOO'.isupper())
        self.assertFalse('Foo'.isupper())

    def test_split(self):
        s = 'hello world'
        self.assertEqual(s.split(), ['hello', 'world'])
        # check that s.split fails when the separator is not a string
        with self.assertRaises(TypeError):
            s.split(2)

if __name__ == '__main__':
    unittest.main()

The setUp() and tearDown() methods allow you to define instructions that will be executed before and after each test method. 

unittest.main() provides a command-line interface to the test script

 Command-Line Interface

python -m unittest test_module1 test_module2 

python -m unittest test_module.TestClass 

python -m unittest test_module.TestClass.test_method 

You can pass in a list with any combination of module names, and fully qualified class or method names.

Organizing test code

Tests can be numerous, and their set-up can be repetitive. Luckily, we can factor out set-up code by implementing a method called setUp(), which the testing framework will automatically call for every single test we run:

import unittest

class WidgetTestCase(unittest.TestCase):
    def setUp(self):
        self.widget = Widget('The widget')

    def test_default_widget_size(self):
        self.assertEqual(self.widget.size(), (50,50),
                         'incorrect default size')

    def test_widget_resize(self):
        self.widget.resize(100,150)
        self.assertEqual(self.widget.size(), (100,150),
                         'wrong size after resize')

tearDown() method that tidies up after the test method has been run

If setUp() succeeded, tearDown() will be run whether the test method succeeded or not