Pytest

HOW TO CONFIGURE AND USE DJANGO PYTEST?

after makeing project and app:

• 1- make tests folder

• 2- install pytest -> pip install pytest-django

• 3- make pytest.ini file and add:

  • [pytest]
  • DJANGO_SETTINGS_MODULE = test.settings
  • python_files = tests.py test_*.py *_tests.py

• 4- write your tests

• 5- for running:

  • pytest -> run all tests
  • pytest a_directory -> directory
  • pytest test_something.py -> tests file
  • pytest test_something.py::single_test -> single test function

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a pattern for writing tests

1- Arrange:

• prepare any state you need to perform the action you want to try.
• trying to prepare and ready test to perform the action at the second stage the act.

• does the test require any objects? or sepecially settings?
• does it need any DB at all to run the test?
• do we need to login in any web, app?
• do we need to connect to any API?

2- Act:

• we're performing an action.
• this could calling a functional method or maybe calling a REST-API or inteacting with a web page.
• typically this step should listen to some sort of response

• this step should have some sort of response
• hhtp response or data which return from an API

3- Assert

• assert expected outcomes
• take the response from the act step and test it agenst the expected outcome of performing the action
• if we were mean to return some data from act step then the assert is going to test to see if that data was indeed returned.
• if we do assert the action or the act and we have return the expected outcome then return True.

pytest fixtuers:

• are functions
• run before/after each test function to which the fixture is applied.

• we use fixtures to collect data from DB or for prepare a DB connection so then we can perform a function in the act to return response and then we can assert the response to check to see if we return an expected outcome.
• fixtures are used to feed data to the tests such as DB connections, URLs to test and input data.

If the project is in a large scale, it becomes hard to manage tests with fixtures. In this case it is better to use factory boy.

Factory Boy?

• fixture replacement tool
• factories are define in a clean and readable manner.
• easy to use factories for complex objects.
• class-based approach
  • SubFactories
  • ForeignKey, reverse ForeignKey, ManyToMany

How to use factory boy?

• install packages:
  • pip install pytest-factoryboy
  • pip install Fake
    • for more information about Fake check this repository: https://github.com/septa-ma/Django-Generate-Fake-Data.git
• build classes -> connect the class in factories to a model.
• register the factory

Factory boy can provide us to built-in strategies.

• If we want factories to produce an object, use build.
  • EX: user_factory.build()
• But if we want to save data to our test db, here we use create.
  • need db access -> @pytest.mark.django_db
  • EX: user_factory.create()

pytest parametrization allows us to define multiple sets of arguments and fixtures and test functional class