[Python + Unit Testing] Write Your First Python Unit Test with pytest

In this lesson you will create a new project with a virtual environment and write your first unit test with pytest. In doing so, you will learn:

• install pytest
• organize your project to support automated test discovery
• setup Visual Code to use pytest as your test engine
• best practice naming conventions for tests in Python

Install:

sudo apt install virtualenv

Create virtualenv inside project folder:

virtualenv -p /usr/local/bin/python3 .env

Source to the env:

source .env/bin/activate

Install the lib:

pip install pytest pylint

VSCode workspace settings:

{
    "python.pythonPath": "${workspaceFolder}/.env/bin/python",
    "python.unitTest.pyTestEnabled": true,
    "python.unitTest.pyTestArgs": [
        "--ignore=.env",
        "-s"
    ],
    "python.envFile": "${workspaceFolder}/.envFile"
}

Code to test:

import pytest
import common_math

class TestCommonMath(object):

    def test_add(self):
        result = common_math.add(1,2)
        assert result == 3

Testing code:

def add(num1, num2):
    return num1 + num2