Which Python is pytest using?

Sunny 105 Published: 11/04/2024

Which Python is pytest using?

Pytest, a popular testing framework for Python, has its roots dating back to the early 2000s when it was first developed as a fork of the unittest module. Since then, it has evolved significantly and gained widespread adoption within the Python community.

When it comes to the version of Python that pytest is using, the answer can be somewhat complex. You see, pytest itself is written in Python, but the version of Python used by pytest is not necessarily tied to the version used for running tests. Here's why:

pytest has its own Python interpreter, known as the "pytest runtime," which is separate from the standard CPython interpreter that you might have installed on your system. This means that when you run a test with pytest, it will use the pytest runtime rather than the standard CPython.

In terms of versioning, the pytest runtime is typically built using the latest version of Python available at the time of its release. For instance, when pytest 6.0 was released in 2021, it used Python 3.9 as its runtime. However, this doesn't mean that you need to have Python 3.9 installed on your system; rather, pytest will use its own runtime environment.

Now, if you want to know the specific version of Python used by the pytest runtime for a given pytest release, I can provide you with some information. According to the pytest documentation, the following are the versions of Python used as the runtime for each pytest release:

Pytest 2.x: Python 2.6 Pytest 3.x: Python 3.4 Pytest 4.x: Python 3.5 Pytest 5.x: Python 3.7 Pytest 6.x: Python 3.9

Keep in mind that these are the versions used for the pytest runtime at the time of each release. You may still be able to run older tests using an earlier version of Python, depending on how your project is set up.

In summary, while pytest itself is written in Python, it has its own runtime environment and does not necessarily require a specific version of Python to be installed on your system. The versions listed above represent the Python used as the pytest runtime at the time each release was made available.

How do I run pytest in Python?

I'm glad you're excited to learn about testing your Python code using Pytest!

To run Pytest, you'll need to have it installed first. You can install Pytest using pip:

pip install pytest

Once installed, you can use the pytest command in your terminal or command prompt to run your tests.

Here are some basic ways to run Pytest:

Running a specific test file: To run all the tests in a specific file, navigate to the directory containing that file and type: 
   pytest .py

For example, if you have a file named test_mymodule.py in your current working directory, you can run it by typing:

   pytest test_mymodule.py
Running all tests: To run all the tests in your project, simply type: 
   pytest
Running specific tests: You can also specify which tests to run using a few different methods: Run specific tests by name: If you want to run only specific tests within a file, use the -k option followed by the test name: 
     pytest -k  .py

For example:

     pytest -k "test_my_function" test_mymodule.py
Run all tests matching a pattern: You can use the -k option with a pattern to run all tests that match it. This is particularly useful when you have a lot of similar test names and want to run only the ones related to a specific feature or module: 
     pytest -k  .py
Running tests with different settings: Pytest allows you to specify different settings, such as running your tests with specific plugins (like pytest-cov for coverage analysis) or modifying the test environment.

Some examples of how you can modify your testing experience:

Run tests in a separate process: This can help you avoid affecting the system state while testing: 
     pytest -n

For example, to run 4 processes concurrently:

     pytest -n 4
Customizing your testing environment: You can use Python's built-in os and sys modules to customize your testing environment: Changing the working directory: Use the chdir function from os to change the current working directory: 
     import os

os.chdir(<new_directory>)
Modifying system variables: You can use os.environ and sys modules to modify or check environment variables.

For example, you might want to set a variable for your test suite to differentiate it from your production code:

     import os

import sys

Set a custom test environment variable

os.environ['TEST_ENV'] = 'unittest'

Check if the test environment is active

if sys.env.get('TEST_ENV') == 'unittest':


print("We're running our unit tests!")

Remember that Pytest offers many more features and options for customizing your testing experience. Be sure to explore its documentation and examples to learn more!

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