How to Install Pytest in Python Step by Step

Pytest is a popular testing framework for Python. It makes writing and running tests easy. This guide will show you how to install Pytest step by step.

Prerequisites

Before installing Pytest, ensure you have Python installed. You can check by running python --version in your terminal.

python --version

If Python is not installed, download it from the official website. Also, ensure pip is available. Pip is Python's package installer.

Install Pytest Using Pip

The easiest way to install Pytest is using pip. Open your terminal or command prompt and run the following command.

pip install pytest

This will download and install Pytest and its dependencies. Wait for the installation to complete.

Verify the Installation

After installation, verify Pytest is installed correctly. Run the following command to check the Pytest version.

pytest --version

You should see the installed Pytest version. If you encounter ModuleNotFoundError, check our guide on How To Solve ModuleNotFoundError.

Create a Simple Test

Now, let's create a simple test to see Pytest in action. Create a file named test_sample.py and add the following code.

 
def add(a, b):
    return a + b

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

This code defines a function add and a test function test_add. The test checks if add(2, 3) returns 5.

Run the Test

To run the test, navigate to the folder containing test_sample.py in your terminal. Then, run the following command.

pytest test_sample.py

Pytest will execute the test and show the results. You should see a message indicating the test passed.

Understanding Pytest Output

Pytest provides detailed output. A passed test shows a green dot. A failed test shows a red F and an error message.

For example, modify the test to fail by changing the assertion to assert add(2, 3) == 6.

 
def test_add():
    assert add(2, 3) == 6

Run the test again. Pytest will show a failure message with details.

Advanced Pytest Features

Pytest offers many advanced features. You can run multiple tests, use fixtures, and generate reports. Explore the official documentation for more.

For now, focus on writing simple tests. As you get comfortable, you can explore these advanced features.

Conclusion

Installing Pytest in Python is simple. Use pip install pytest to get started. Write tests in files prefixed with test_ and run them with the pytest command.

Pytest helps ensure your code works as expected. Start testing your Python projects today. If you face issues, refer to the ModuleNotFoundError guide.