How to Install `mock` in Python

v5.2.0 Testing & QA Python >=3.6

Rolling backport of unittest.mock for all Pythons

Install pip install mock

What is mock?

Rolling backport of unittest.mock for all Pythons

mock is a library for testing in Python. It allows you to replace parts of your system under test with mock objects and make assertions about how they have been used.

mock is now part of the Python standard library, available as `unittest.mock ` in Python 3.3 onwards.

This package contains a rolling backport of the standard library mock code compatible with Python 3.6 and up.

Documentation → PyPI page → Author: Testing Cabal

Quick Start

Minimal example to get started with mock:

import mock

print(mock.__version__)

Installation

pip (standard)

pip install mock

Virtual environment (recommended)

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

pip3

pip3 install mock

conda

conda install -c conda-forge mock

Poetry

poetry add mock

Verify the Installation

After installing, confirm the package is available:

python -c "import mock; print(mock.__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 mock with pip.

ModuleNotFoundError: No module named 'mock'

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

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

ModuleNotFoundError: No module named 'mock' (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 mock to install into the interpreter you are running.

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

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

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

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 mock. 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 mock

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 mock

Recent Releases

Version	Released
`5.2.0` latest	2025-03-03
`5.1.0`	2023-07-11
`5.0.2`	2023-04-16
`5.0.1`	2023-01-09
`5.0.0`	2022-12-28

Full release history on PyPI →

Manage mock

Upgrade to latest version

pip install --upgrade mock

Install a specific version

pip install mock==5.2.0

Uninstall

pip uninstall mock

Check what is installed

pip show mock

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

How to Install mock in Python