pythoninthegrass
commented
6 months ago FWIW this is the raw markdown if you can't bust into my account
How to write tests with pytest
whoami
- Lance Stephens
- DevOps Engineer
- Pretty okay Pythonista 🐍
Agenda
- Zoom basic tells me I have 40 minutes
- I'll try to keep it to 30 minutes for the remote folks
- 10 minutes for Q&A
Agenda
- What is pytest?
- Why pytest?
- Unit tests
- Integration tests
- Mocking
- Fixtures
- Demo
- Q&A
- Sources
What is pytest? ^1
The pytest framework makes it easy to write small, readable tests, and can scale to support complex functional testing for applications and libraries.
Features
- Detailed info on failing assert statements (no need to remember self.assert* names)
- Auto-discovery of test modules and functions
- Modular fixtures for managing small or parametrized long-lived test resources
- Can run unittest (including trial) test suites out of the box
- Python 3.8+ or PyPy 3
- Rich plugin architecture, with over 1300+ external plugins and thriving community
Why pytest?
- It's very easy to get started
- Barrier to entry is low compared to vanilla
unittest - Supports unit tests, integration tests, and end-to-end (E2E) tests
- Barrier to entry is low compared to vanilla
- There's a lot of community support (11K+ stars on GitHub)
- Official Playwright plugin for integration and E2E testing
Wildly detailed overview by somebody else ^2
Unit tests
unittest is Python's built-in testing framework.
The unittest unit testing framework was originally inspired by JUnit and has a similar flavor as major unit testing frameworks in other languages. It supports test automation, sharing of setup and shutdown code for tests, aggregation of tests into collections, and independence of the tests from the reporting framework.
A unit is the smallest testable part of an application. In procedural programming, a unit could be an entire module, but it is more commonly an individual function or method.
Unit tests
Exhibit A ^4
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()Integration tests
Integration testing is the phase in software testing in which the whole software module is tested... It occurs after unit testing and before system testing. Integration testing takes as its input modules that have been unt tested, groups them in larger aggregates, applies tests defined in an integration test plan to those aggregates, and delivers as its output the integrated system ready for system testing. ^5
Integration tests
Exhibit B
import unittest
class TestBasic(unittest.TestCase):
def setUp(self):
# Load test data
self.app = App(database='fixtures/test_basic.json')
def test_customer_count(self):
self.assertEqual(len(self.app.customers), 100)
def test_existence_of_customer(self):
customer = self.app.get_customer(id=10)
self.assertEqual(customer.name, "Org XYZ")
self.assertEqual(customer.address, "10 Red Road, Reading")
class TestComplexData(unittest.TestCase):
def setUp(self):
# load test data
self.app = App(database='fixtures/test_complex.json')
def test_customer_count(self):
self.assertEqual(len(self.app.customers), 10000)
def test_existence_of_customer(self):
customer = self.app.get_customer(id=9999)
self.assertEqual(customer.name, u"バナナ")
self.assertEqual(customer.address, "10 Red Road, Akihabara, Tokyo")
if __name__ == '__main__':
unittest.main()Mocking
TODO
Fixtures
TODO
Demo
TODO
Q&A
Questions?
alkrauss48
Hey Aaron!
Testing out Simple Slides for my presentation this weekend. Very polished overall and easy to use!
Not sure how much access you have, but my pytest talk has some silly behavior atm:
Entirely possible that it's me holding markdown wrong. Know other apps like Deckset splits pages by
---kinda like front matter in YAML.Using macOS 12.7.4 (21H1123), Firefox 124.0.2.
Lmk if you need any more details.