ModuleNotFoundError: No module named 'pytest' in Python

# ModuleNotFoundError: No module named 'pytest' in Python

The Python "ModuleNotFoundError: No module named 'pytest'" occurs when we forget to install the pytest module before importing it or install it in an incorrect environment.

To solve the error, install the module by running the pip install pytest command.

Open your terminal in your project's root directory and install the pytest package.

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# 👇️ In a virtual environment or using Python 2
pip install pytest

# 👇️ For Python 3 (could also be pip3.10 depending on your version)
pip3 install pytest

# 👇️ If you get a permissions error
sudo pip3 install pytest
pip install pytest --user

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install pytest

# 👇️ For Python 3 (could also be pip3.10 depending on your version)
python3 -m pip install pytest

# 👇️ Using py alias (Windows)
py -m pip install pytest

# 👇️ For Anaconda
conda install -c anaconda pytest

# 👇️ For Jupyter Notebook
!pip install pytest

After installing the pytest module, you should be able to run your test file as pytest your_module.py.

For example, here is a test_sample.py file that you can run with pytest test_sample.py.

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def increment(x):
    return x + 1


def get_answer():
    assert increment(5) == 7

get_answer()

# Common causes of the error

The error occurs for multiple reasons:

1. Not having the pytest package installed by running pip install pytest.
2. Installing the package in a different Python version than the one you're using.
3. Installing the package globally and not in your virtual environment.
4. Your IDE running an incorrect version of Python.

If the error persists, get your Python version and make sure you are installing the package using the correct Python version.

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python --version

For example, my Python version is 3.10.4, so I would install the pytest package with pip3.10 install pytest.

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pip3.10 install pytest

# 👇️ If you get a permissions error use pip3 (NOT pip3.X)
sudo pip3 install pytest

Notice that the version number corresponds to the version of pip I'm using.

If the PATH for pip is not set up on your machine, replace pip with python3 -m pip:

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# 👇️ Make sure to use your version of Python, e.g. 3.10
python3 -m pip install pytest

If the error persists, try restarting your IDE and development server/script.

# Check if the package is installed

You can check if you have the pytest package installed by running the pip show pytest command.

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# 👇️ Check if you have pytest installed
pip show pytest

# 👇️ If you don't have pip set up in PATH
python -m pip show pytest

# Make sure your IDE is using the correct Python version

If the package is not installed, make sure your IDE is using the correct version of Python.

For example, In VSCode, you can press CTRL + Shift + P or (⌘ + Shift + P on Mac) to open the command palette.

Then type "Python select interpreter" in the field.

Then Select the correct Python version from the dropdown menu.

# Install the package in a Virtual Environment

If you are using a virtual environment, make sure you are installing pytest in your virtual environment and not globally.

You can try creating a virtual environment if you don't already have one.

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# 👇️ Use the correct version of Python when creating VENV
python3 -m venv venv

# 👇️ Activate on Unix or MacOS
source venv/bin/activate

# 👇️ Activate on Windows (cmd.exe)
venv\Scripts\activate.bat

# 👇️ Activate on Windows (PowerShell)
venv\Scripts\Activate.ps1

# 👇️ Install pytest in your virtual environment
pip install pytest

Your virtual environment will use the version of Python that was used to create it.

You also shouldn't be declaring a variable named pytest as that would also shadow the original module.

# Try reinstalling the package

If the error is not resolved, try to uninstall the pytest package and then reinstall it.

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# 👇️ Check if you have pytest installed
pip show pytest

# 👇️ If you don't have pip set up in PATH
python -m pip show pytest

# 👇️ Uninstall pytest
pip uninstall pytest

# 👇️ If you don't have pip set up in PATH
python -m pip uninstall pytest

# 👇️ Install pytest
pip install pytest

# 👇️ If you don't have pip set up in PATH
python -m pip install pytest

Try restarting your IDE and development server/script.

You can also try to upgrade the version of the pytest package.

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pip install pytest --upgrade

# 👇️ If you don't have pip set up in PATH
python -m pip install pytest --upgrade

# Import "pytest" could not be resolved from source Pylance

The error "Import "pytest" could not be resolved from source Pylance" occurs when the pytest module is not installed or you have selected the incorrect Python interpreter in your IDE (e.g. Visual Studio Code).

To solve the error, install pytest and select the correct Python interpreter in your IDE.

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Import "pytest" could not be resolved from source Pylance(reportMissingModuleSource) [Ln 1, Col 8]

# Make sure the correct Python interpreter is selected in your IDE

If you have multiple Python versions installed on your machine, you might have installed the pytest package using the incorrect version or your IDE might be set up to use a different version.

For example, In Visual Studio Code you can:

1. Press CTRL + Shift + P or (⌘ + Shift + P on macOS) to open the command palette.

Then type "Python select interpreter" in the search field.

2. Select the correct Python version from the dropdown menu.

If the error persists, try restarting your IDE and development server/script. VSCode often glitches and a reboot resolves the issue.

If the error is not resolved, try to use the Visual Studio Code terminal to install the pytest module.

You can press CTRL + ` (Backtick) on your keyboard to open the Visual Studio code terminal.

Once you open the terminal, Visual Studio Code will automatically activate your virtual environment (if you have one).

Run the pip install pytest command.

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pip install pytest

If the error persists, try to select the Python interpreter by specifying the path:

1. Press CTRL + Shift + P or (⌘ + Shift + P on Mac) to open the command palette.
2. Type "Python select interpreter" in the field.

3. Select "Enter interpreter path...".

4. Click on "Find".

5. In the window that opens, navigate to your Python executable:

• If you have a virtual environment on Windows, click on your venv folder, then double-click on the Scripts folder, select the python.exe file and then Select interpreter.

• If you have a virtual environment on macOS or Linux, click on your venv folder, then double-click on the bin folder, select the python file and then Select interpreter.

• If you don't have a virtual environment, use one of the following commands to get your path to your python.exe or python executable, specify the path to the file and select the executable.

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where python

python -c "import sys; print(sys.executable)"

If the error persists, try restarting your IDE and development server/script.

# Alternatively, use a comment to disable the warning

If none of the suggestions helped, you can use a comment to disable the Pylance warning in your IDE.

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import pytest  # type: ignore

print(pytest)

You simply have to add the # type: ignore command on the same line as the import statement to disable the check for the specific import.

# Table of Contents

1. Install pytest on Windows
2. Install pytest on macOS or Linux
3. Install pytest in Visual Studio Code
4. Install pytest in PyCharm
5. Install pytest in Anaconda
6. Install pytest in Jupyter Notebook

# Install pytest on Windows

To install the pytest module on Windows:

1. Type CMD in the search bar and open the Command Prompt application.
2. Type pip install pytest and press Enter.

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pip install pytest

# 👇️ For Python 3
pip3 install pytest

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install pytest

# 👇️ For Python 3
python3 -m pip install pytest

# 👇️ Using py alias
py -m pip install pytest

# 👇️ If you get a permissions error
pip install pytest --user

# 👇️ For Anaconda
conda install -c anaconda pytest

After installing the pytest module, you should be able to run your test file as pytest your_module.py.

For example, here is a test_sample.py file that you can run with pytest test_sample.py.

Copied!
def increment(x):
    return x + 1


def get_answer():
    assert increment(5) == 7

get_answer()

If the installation command doesn't succeed, try running CMD as an administrator.

If you get the error 'pip' is not recognized as an internal or external command, use the python -m command when installing pytest.

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python -m pip install pytest

python3 -m pip install pytest

py -m pip install pytest

Alternatively, you can install the pytest module in a virtual environment:

1. Open the root directory of your project.
2. Press Shift and right-click in Explorer.

3. Click on "Open PowerShell window here".
4. Run the following commands.

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# 👇️ Might also be: "python3 -m venv venv"
python -m venv venv

# 👇️ Activate on Windows (PowerShell)
venv\Scripts\Activate.ps1

# 👇️ Activate on Windows (cmd.exe)
venv\Scripts\activate.bat

# 👇️ Install pytest in your virtual environment
pip install pytest

If the python -m venv venv command doesn't work, try the following 2 commands:

• python3 -m venv venv
• py -m venv venv.

If you see an error message that ps1 cannot be loaded because running scripts is disabled on this system, run the following command, type "yes" when prompted and rerun the activation command.

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Set-ExecutionPolicy RemoteSigned -Scope CurrentUser

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pip show pytest
pip3 show pytest

python -m pip show pytest
python3 -m pip show pytest

The pip show pytest command will either state that the package is not installed or show a bunch of information about the package, including the location where the package is installed.

# Install pytest on macOS or Linux

To install pytest on macOS or Linux:

1. Search for "terminal" and start the application.
2. Type pip install pytest and press Enter.

Copied!
pip install pytest

# 👇️ For Python 3
pip3 install pytest

# 👇️ If you get a permissions error
sudo pip3 install pytest

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install pytest

# 👇️ For Python 3
python3 -m pip install pytest

# 👇️ Alternative if you get a permissions error
pip install pytest --user

# 👇️ For Anaconda
conda install -c anaconda pytest

After installing the pytest module, you should be able to run your test file as pytest your_module.py.

For example, here is a test_sample.py file that you can run with pytest test_sample.py.

Copied!
def increment(x):
    return x + 1


def get_answer():
    assert increment(5) == 7

get_answer()

If you get an error that pip isn't found, use the python -m command.

Copied!
python -m pip install pytest

python3 -m pip install pytest

If you get a permissions error, prefix the command with sudo.

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sudo pip install pytest

sudo pip3 install pytest

Alternatively, you can install the pytest package in a virtual environment:

1. Open your terminal in the root directory of your project.
2. Run the following commands.

Copied!
# 👇️ Could also be "python -m venv venv"
python3 -m venv venv

# 👇️ Activate virtual env on macOS or Linux
source venv/bin/activate

# 👇️ Install pytest in your virtual environment
pip install pytest

Your virtual environment will use the version of Python that was used to create it.

You can use the pip show command to verify pytest has been installed successfully.

Copied!
pip show pytest
pip3 show pytest

python -m pip show pytest
python3 -m pip show pytest

The pip show pytest command will either state that the package is not installed or show a bunch of information about the package.

# Install pytest in Visual Studio Code

To install pytest in Visual Studio Code:

1. Press CTRL + ` (Backtick) on your keyboard to open the terminal.
2. Run the pip install pytest command to install the pytest module.

Copied!
pip install pytest

# 👇️ For Python 3
pip3 install pytest

# 👇️ If you get a permissions error
sudo pip3 install pytest

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install pytest

# 👇️ For Python 3
python3 -m pip install pytest

# 👇️ Using py alias
py -m pip install pytest

# 👇️ Alternative if you get a permissions error
pip install pytest --user

After installing the pytest module, you should be able to run your test file as pytest your_module.py.

For example, here is a test_sample.py file that you can run with pytest test_sample.py.

Copied!
def increment(x):
    return x + 1


def get_answer():
    assert increment(5) == 7

get_answer()

When installing Python modules in Visual Studio code, make sure that your IDE is configured to use the correct Python version.

Press CTRL+Shift+P or (⌘ + Shift + P on Mac) to open the command palette.

Then type "Python select interpreter" in the field.

Then Select the correct Python version from the dropdown menu.

You can use the python --version command if you need to get your version of Python.

Copied!
python --version
python3 --version

You can also try creating a virtual environment if you don't already have one.

Copied!
# 👇️ Could also be "python -m venv venv" or "py -m venv venv"
python3 -m venv venv

# 👇️ Activate on Unix or MacOS
source venv/bin/activate

# 👇️ Activate on Windows (cmd.exe)
venv\Scripts\activate.bat

# 👇️ Activate on Windows (PowerShell)
venv\Scripts\Activate.ps1

# 👇️ Install pytest in your virtual environment
pip install pytest

Your virtual environment will use the version of Python that was used to create it.

# Install pytest in PyCharm

To install pytest in PyCharm:

1. Press Alt+F12 on your keyboard to open the terminal.
2. Run the pip install pytest command to install the pytest module.

Copied!
pip install pytest

# 👇️ For Python 3
pip3 install pytest

# 👇️ If you get a permissions error
sudo pip3 install pytest

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install pytest

# 👇️ For Python 3
python3 -m pip install pytest

# 👇️ Using py alias
py -m pip install pytest

# 👇️ Alternative if you get a permissions error
pip install pytest --user

After installing the pytest module, you should be able to run your test file as pytest your_module.py.

For example, here is a test_sample.py file that you can run with pytest test_sample.py.

Copied!
def increment(x):
    return x + 1


def get_answer():
    assert increment(5) == 7

get_answer()

Alternatively, you can use the IDE itself to install the module.

1. Click on "File" > "Settings" > "Project" > "Python Interpreter".
2. Click on the + icon and type pytest.
3. Click on "Install Package".

Click on "File" > "Settings" > "Project" > "Python Interpreter".

Then Select the correct Python version from the dropdown menu.

You can use the python --version command if you need to get your version of Python.

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python --version
python3 --version

# Install pytest in Anaconda

To install pytest in Anaconda:

1. Open your Anaconda Navigator.
2. Click on "Environments" and select your project.
3. Type pytest in the search bar to the right.
4. Tick the pytest package and click on "Apply".

After installing the pytest module, you should be able to run your test file as pytest your_module.py.

For example, here is a test_sample.py file that you can run with pytest test_sample.py.

Copied!
def increment(x):
    return x + 1


def get_answer():
    assert increment(5) == 7

get_answer()

Alternatively, you can install the pytest package with a command.

If you are on Windows, search for "Anaconda Prompt" and open the application.

If you are on macOS or Linux, open your terminal.

Run the following command to install the pytest package.

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# 👇️ Using conda
conda install -c anaconda pytest

# 👇️ Alternatively use `pip`
pip install pytest

# 👇️ For Python 3
pip3 install pytest

# 👇️ If you get a permissions error
sudo pip3 install pytest

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install pytest

# 👇️ For Python 3
python3 -m pip install pytest

# 👇️ Using py alias
py -m pip install pytest

# 👇️ Alternative if you get a permissions error
pip install pytest --user

Click on the following article if you need to install a specific version of the package using Anaconda.

# Install pytest in Jupyter Notebook

To install pytest in Jupyter Notebook:

1. Open your terminal and type "jupyter notebook".

2. Click on "New" and then "Terminal" in the browser tab.

3. Type pip install pytest and press Enter.

Copied!
# 👇️ Using pip
pip install pytest

# 👇️ For Python 3
pip3 install pytest

# 👇️ If you get a permissions error
sudo pip3 install pytest

# 👇️ If you don't have pip in your PATH environment variable
python -m pip install pytest

# 👇️ For Python 3
python3 -m pip install pytest

# 👇️ Using py alias
py -m pip install pytest

# 👇️ Using conda
conda install -c anaconda pytest

# 👇️ Alternative if you get a permissions error
pip install pytest --user

After installing the pytest module, you should be able to run your test file as pytest your_module.py.

For example, here is a test_sample.py file that you can run with pytest test_sample.py.

Copied!
def increment(x):
    return x + 1


def get_answer():
    assert increment(5) == 7

get_answer()

Alternatively, you can use the Python ipykernel.

1. Open your terminal and type "jupyter notebook".

2. Click on "New" and then click on "Python 3 (ipykernel)".

3. Type !pip install pytest and click on "Run".

Note that the pip install command must be prefixed with an exclamation mark if you use this approach.

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!pip install pytest

Once you type the command, click "Run" to install the pytest module.

If you get a permissions error, e.g. "[WinError: 5] Access is denied", add the --user option to the installation command.

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!pip install pytest --user

If the error persists, try to restart the Jupyter Kernel and rerun the command.