Unittest usage instance in Python

This article illustrates the use of unittest in Python as an example and shares it with you for your reference. Specific usage analysis is as follows:

1. Unittest module contains the function of writing and running unittest. All customized test classes should be integrated with unitest.testcase class.
Setup (): run before each test function runs
Teardown (): execute after each test function is run
SetUpClass (): must use the @classmethod decorator and run all tests once before running them
TearDownClass (): you must use the @classmethod decorator and run all tests once they are run

2. Sample code:

# The file name runtest.py
import random
import unittest

class TestSequenceFunctions(unittest.TestCase):

  def setUp(self):
    self.seq = list(range(10))

  def test_shuffle(self):
    # make sure the shuffled sequence does not lose any elements
    random.shuffle(self.seq)
    self.seq.sort()
    self.assertEqual(self.seq, list(range(10)))

    # should raise an exception for an immutable sequence
    self.assertRaises(TypeError, random.shuffle, (1,2,3))

  def test_choice(self):
    element = random.choice(self.seq)
    self.assertTrue(element in self.seq)

  def test_sample(self):
    with self.assertRaises(ValueError):
      random.sample(self.seq, 20)
    for element in random.sample(self.seq, 5):
      self.assertTrue(element in self.seq)

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

3. How to run: run runtest.py directly from the command line

You can skip test method or test class using the unitest. Skip decorator family, which includes:
Unittest.skip (reason): skip the test unconditionally
Skipif (conditition,reason): pass the test when condititon is true
@unittest.skipunless(condition,reason): skip the test if condition is not true

You can customize the skip decorator

# This is a custom one skip decorrator
def skipUnlessHasattr(obj, attr):
  if hasattr(obj, attr):
    return lambda func: func
  return unittest.skip("{!r} doesn't have {!r}".format(obj, attr))

Skip decorator sample code:

class MyTestCase(unittest.TestCase):

  @unittest.skip("demonstrating skipping")
  def test_nothing(self):
    self.fail("shouldn't happen")

  @unittest.skipIf(mylib.__version__ < (1, 3),
           "not supported in this library version")
  def test_format(self):
    # Tests that work for only a certain version of the library.
    pass

  @unittest.skipUnless(sys.platform.startswith("win"), "requires Windows")
  def test_windows_support(self):
    # windows specific testing code
    pass

@unittest.skip("showing class skipping")
class MySkippedTestCase(unittest.TestCase):
  def test_not_run(self):
    pass

4. Expected failure: use the @unittest. ExpectedFailure decorator, which does not count the number of cases that fail if the test fails

I hope that this article has helped you to learn Python programming.