Getting started with testing in Python

notes.rst

Why Test

• Tells you when your code is broken
• Manual testing sucks

• Prevent against regressions

  • Upgrading dependencies
  • Refactoring

• Documentation

  • Other devs can read your tests to see how you intended your code to be used

• Helps with design

  • Code that is hard to test is a code smell
  • Code that is easy to test knows as little as possible about the outside world

How to Write/Run Tests

• doctest

  • fragile/ugly
  • should only be used to ensure test code in documentation is correct

• unittest

  • xUnit style
  • lots of boilerplate/ugly self.assertEqual(x, y) ??

• py.test/nose

  • native assertions/pretty! assert x == y
  • powerful
  • fixtures
  • useful failure messages
  • pdb integration
  • parametrize/marking tests

What kinds of Tests to Write

• Unit tests
• Integration tests
• System/Functional/Acceptance tests

Testing Workflows

• Bug fixing/regression
• Test after
• Test first
• Spike

Overtime

• mock/patching
• coverage.py
• demo actual test suite