Introduction to pytest

• This documents my learning on the course from Test Automation University: https://testautomationu.applitools.com/pytest-tutorial/.
• Date completed: 8 November 2022.
• Time spent: ~5 hours
• The work is handcoded by yours truly (except for example code that were copied and pasted).

Environment

• MacOS Ventura 13.0
• Atom
• Terminal
• Python 3.9.13
• pytest 7.2.0

Directory

• /stuff and /tests are project files (yes, you read it right. It says 'stuff', not sure why the tutor told me to use that 🤣)
• /output stores terminal output for the tests I ran.
• /quiz stores the quiz answers that I submitted.

Chapter 1 - The first test case

• Simple setup, installed pytest through pip and created a python file to run.

Chapter 2 - Failed test case

• Assertion introspection is seems useful, saves you a few secs going into the code to see what's wrong. Failure introspection should be part of our daily life as well (I jest).

Chapter 3 - Asserting exceptions

• I got the first question wrong. I answered 'To catch exceptions raised by the pytest framework.' but I think the answer is 'To verify that the code under test raises expected exceptions.'. After resubmitting, everything came back correct!

Chapter 4 - Parameterized tests

• TIL an underscore prefix means that the variable is private. For example, _count denotes a private var for the count variable.
• Class properties are objects you can usually 'Get' and 'Set'.

Chapter 5 - Testing classes

• I learned about Arrange, Act and Assert. This can confuse me because I previously learned the cybersecurity AAA which has a different meaning.

Chapter 6 - Fixtures

• Fixtures handle the test setup (Arrange step) by injecting objects as required dependencies for the test functions. Improves readability and maintainability of tests.
• The yield keyword enables test setup and cleanup, it's like the act of drawing a line in the sand. Anything before the keyword is setup and after the keyword is cleanup.
• Fixtures can be placed in conftest.py within the /tests folder. This allows multiple modules to use the same fixture.

Chapter 7 - Commands and Configs

• --verbose and --quiet controls terminal output.
• --exitfirst stops the test after the first failure. pytest usually continues tests by default regardless of test failures.
• --maxfail=(number) limits number of failures before stopping.
• There is a pytest.ini file for specifying pytest configs.
  • addopts specify options that you would otherwise type out in the command line.

Chapter 8 - Filtering tests

• You can run tests in a certain folder, individual modules, or even specific functions in a module. By default, pytest runs tests that it can find in the pwd.
• You can even run tests with a substring in it with the -k option, wow! (UPDATE: You can also use and, or, and not).
• @pytest.mark.(name) decorator is another option if you want to run a custom list of tests. They work like tags. However, these markers need to be defined in the pytest.ini as well.
  • Tried this with my first test case. I marked as 'fave' and was able to run just that test case with the -m option.

Chapter 10 - Useful plugins

• pytest-html for prettier reports.
• pytest-cov for check code coverage statistics, this also can be outputted as html.
• pytest-xdist allows parallel execution of tests. I guess 'xdist' means distributed execution.