How to Install `pytest` in Python

v9.0.3 Testing & QA Python >=3.10

pytest: simple powerful testing with Python

Install pip install pytest

What is pytest?

pytest: simple powerful testing with Python

The `` framework makes it easy to write small tests, yet scales to support complex functional testing for applications and libraries.

# content of testsample.py def inc(x): return x + 1

def testanswer(): > assert inc(3) == 5 E assert 4 == 5 E + where 4 = inc(3)

PyPI page → Author: Holger Krekel, Bruno Oliveira, Ronny Pfannschmidt, Floris Bruynooghe, Brianna Laugher, Freya Bruhin, Others (See AUTHORS)

Quick Start

Minimal example to get started with pytest:

# test_math.py
def add(x, y):
    return x + y

def test_add():
    assert add(2, 3) == 5
    assert add(-1, 1) == 0

def test_add_strings():
    assert add("a", "b") == "ab"

# Run: pytest test_math.py -v

Installation

pip (standard)

pip install pytest

Virtual environment (recommended)

python -m venv venv
source venv/bin/activate   # Windows: venv\Scripts\activate
pip install pytest

pip3

pip3 install pytest

conda

conda install -c conda-forge pytest

Poetry

poetry add pytest

Dependencies

Installing pytest will also install these packages:

colorama exceptiongroup iniconfig packaging pluggy pygments tomli

Verify the Installation

After installing, confirm the package is available:

python -c "import pytest; print(pytest.__version__)"

If this prints a version number, installation succeeded. If you see a ModuleNotFoundError, see the errors section below.

Installation Errors

Common errors when installing pytest with pip.

ModuleNotFoundError: No module named 'pytest'

Cause: The package is not installed in the current Python environment.

Fix: Run pip install pytest. If using a virtual environment, ensure it is activated first.

ModuleNotFoundError: No module named 'pytest' (installed but still failing)

Cause: pip installed the package into a different Python than the one running your script.

Fix: Use python -m pip install pytest to install into the interpreter you are running.

ImportError: cannot import name 'X' from 'pytest'

Cause: The function or class does not exist in the installed version.

Fix: Check the version with pip show pytest and upgrade with pip install --upgrade pytest.

pip: command not found

Cause: pip is not in PATH or Python was not added to PATH during installation.

Fix: Try python -m pip install pytest. On macOS/Linux try pip3.

PermissionError: [Errno 13] Permission denied

Cause: No write access to the system Python package directory.

Fix: Use a virtual environment, or add --user: pip install --user pytest

SSL: CERTIFICATE_VERIFY_FAILED

Cause: pip cannot verify PyPI's SSL certificate — common behind corporate proxies.

Fix: Try: pip install --trusted-host pypi.org --trusted-host files.pythonhosted.org pytest

Runtime Errors

Common errors when using pytest after installation.

fixture 'X' not found

Cause: Fixture not in scope, misspelled, or the plugin providing it is not installed.

Fix: Define the fixture in conftest.py. For plugin fixtures (e.g., pytest-asyncio), install the plugin.

ImportError while collecting test file

Cause: pytest cannot import the test module.

Fix: Run python -c 'import your_module' to reproduce the error directly.

Recent Releases

Version	Released
`9.0.3` latest	2026-04-07
`9.0.2`	2025-12-06
`9.0.1`	2025-11-12
`9.0.0`	2025-11-08
`8.4.2`	2025-09-04

Full release history on PyPI →

Manage pytest

Upgrade to latest version

pip install --upgrade pytest

Install a specific version

pip install pytest==9.0.3

Uninstall

pip uninstall pytest

Check what is installed

pip show pytest

Last updated: 2026-04-11 • Data from PyPI

How to Install pytest in Python