python-testing-with-pytests

Description

This project is a tutorial for learning pytest, based on book "Python testing with pytest"

Useful commands

How to create virtualenv

$ pip3 install -U virtualenv
$ python3 -m virtualenv -p $(which python3) python-testing-with-pytests
$ source venv/bin/activate
$ pip install pytest

How to activate virtualenv

source <project-name>/bin/activate

How to understand, that you're in venv

pip -V    

How to deactivate virtualenv

deactivate

In order to see all installed packages in current env: pip list

In order to run tests - go to the desired directory and run pytest or pytest tasks/ or pytest tasks/test_three.py

Run one test

$ pytest -v tasks/test_four.py::test_asdict

Pytest Options

Option	Description	Example
--collect-only	shows all modules and functions	pytest tasks/ --collect-only
-k	allows to select tests via expression	pytest tasks/ -k "asdict" --collect-only OR pytest -v --tb=no -k="add and get" --collect-only
-m	run tests with specified decorator	pytest tasks/ -m run_these_please
-x, -exitfirst	if used, running stops on 1 failure	pytest -x
-maxfail=num	max couts of tests, which can be failed	pytest -maxfail=2
--tb=no	disabled showing traceback	pytest --tb=no
--tb=short	provides short info about error	pytest --tb=no
--tb=line	shows 1 line of error	pytest --tb=line
-s	allows to see print statement in console	pytest -s
--lf	allows to rerun failed tests	pytest --lf
--ff	runs firstly 1 fail and then all other tests	pytest --ff
-v	allows to see add info	pytests -v
-q	increases info about test running to minimum	pytest -q
--showlocals -l	shows local variables, if test fails	pytest -l
--durations=N	shows the N numbers slowest tests	pytest --durations=3# python-testing-with-pytests
-c <path-to-config-file/pytest.ini>	allows to specify path to pytest.ini file. by default it tries to find it in cur dir	pytest -v -m 'smoke' -c tests/pytest.ini
-rs	reason of skipping test	pytest -rs
-s	allows to know additional info about errors/passed, etc., to see print statements!
--setup-show	show log of fixtures, what they actually do	pytest --setup-show
--fixtures .py	allows to see all fixtures, which used in this test file	pytest --fixtures test_add.py
--cache-show	shows last failures info	pytest --cache-show
--clear-cache	clear cache before session	pytest --clear-cache
--doctest-modules	allows to test function in docstrings	pytest --doctest-modules

Debugging options.

We can debug our tests, using built-it --pdb. With -x (1 failed tests) pdb opens for 1 failed test. Options:

Option	Description
p/print expr	print the value of exp
pp epxr	pretty prints the value of expr.
l/list	list the point of failure and 5 lines of code above and below
l/list begin, end	list specific line numbers.
a/args	print args of current fnction
u/up	Move up 1 level in the stack trace.
d/down	Moves down 1 level in the stack trace.
q	Quits the debugging session

For running single test

pytest /path/to/<test-module-name>.py::<test-method>.py

For running class

pytest /path/to/<test-module-name>.py::<test-class>

For running method in class

pytest /path/to/<test-module-name>.py::<test-class>::<test-method>.py

In order to run parametrized function directly with parameteres (use quotes, if there're any spaces)

pytest -v "test_add_variety.py::test_add_3[sleep-None-False]"

Important!

By using a yield statement instead of return, all the code after the yield statement serves as the teardown code: When you use return, all code after return doesn't execute