How to Install pytest in Python?

by 
pip install pytest

The Python pytest library is among the top 100 Python libraries, with more than 28,306,860 downloads. This article will show you everything you need to get this installed in your Python environment.

Alternatively, you may use any of the following commands to install pytest, depending on your concrete environment. One is likely to work!

💡 If you have only one version of Python installed:
pip install pytest

💡 If you have Python 3 (and, possibly, other versions) installed:
pip3 install pytest

💡 If you don't have PIP or it doesn't work
python -m pip install pytest
python3 -m pip install pytest

💡 If you have Linux and you need to fix permissions (any one):
sudo pip3 install pytest
pip3 install pytest --user

💡 If you have Linux with apt
sudo apt install pytest

💡 If you have Windows and you have set up the py alias
py -m pip install pytest

💡 If you have Anaconda
conda install -c anaconda pytest

💡 If you have Jupyter Notebook
!pip install pytest
!pip3 install pytest

How to Install pytest on Windows?

  1. Type "cmd" in the search bar and hit Enter to open the command line.
  2. Type “pip install pytest” (without quotes) in the command line and hit Enter again. This installs pytest for your default Python installation.
  3. The previous command may not work if you have both Python versions 2 and 3 on your computer. In this case, try "pip3 install pytest" or “python -m pip install pytest“.
  4. Wait for the installation to terminate successfully. It is now installed on your Windows machine.

Here’s how to open the command line on a (German) Windows machine:

Open CMD in Windows

First, try the following command to install pytest on your system:

pip install pytest

Second, if this leads to an error message, try this command to install pytest on your system:

pip3 install pytest

Third, if both do not work, use the following long-form command:

python -m pip install pytest

The difference between pip and pip3 is that pip3 is an updated version of pip for Python version 3. Depending on what’s first in the PATH variable, pip will refer to your Python 2 or Python 3 installation—and you cannot know which without checking the environment variables. To resolve this uncertainty, you can use pip3, which will always refer to your default Python 3 installation.

How to Install pytest on Linux?

You can install pytest on Linux in four steps:

  1. Open your Linux terminal or shell
  2. Type “pip install pytest” (without quotes), hit Enter.
  3. If it doesn’t work, try "pip3 install pytest" or “python -m pip install pytest“.
  4. Wait for the installation to terminate successfully.

The package is now installed on your Linux operating system.

How to Install pytest on macOS?

Similarly, you can install pytest on macOS in four steps:

  1. Open your macOS terminal.
  2. Type “pip install pytest” without quotes and hit Enter.
  3. If it doesn’t work, try "pip3 install pytest" or “python -m pip install pytest“.
  4. Wait for the installation to terminate successfully.

The package is now installed on your macOS.

How to Install pytest in PyCharm?

Given a PyCharm project. How to install the pytest library in your project within a virtual environment or globally? Here’s a solution that always works:

  • Open File > Settings > Project from the PyCharm menu.
  • Select your current project.
  • Click the Python Interpreter tab within your project tab.
  • Click the small + symbol to add a new library to the project.
  • Now type in the library to be installed, in your example "pytest" without quotes, and click Install Package.
  • Wait for the installation to terminate and close all pop-ups.

Here’s the general package installation process as a short animated video—it works analogously for pytest if you type in “pytest” in the search field instead:

Make sure to select only “pytest” because there may be other packages that are not required but also contain the same term (false positives):

How to Install pytest in a Jupyter Notebook?

To install any package in a Jupyter notebook, you can prefix the !pip install my_package statement with the exclamation mark "!". This works for the pytest library too:

!pip install my_package

This automatically installs the pytest library when the cell is first executed.

How to Resolve ModuleNotFoundError: No module named ‘pytest’?

Say you try to import the pytest package into your Python script without installing it first:

import pytest
# ... ModuleNotFoundError: No module named 'pytest'

Because you haven’t installed the package, Python raises a ModuleNotFoundError: No module named 'pytest'.

To fix the error, install the pytest library using “pip install pytest” or “pip3 install pytest” in your operating system’s shell or terminal first.

See above for the different ways to install pytest in your environment.

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