Getting Started With Unit Testing

04/26/23·2 min read

Unit Testing

Unit testing is a crucial part of software development, and pytest is one of the most popular testing frameworks for Python.

Basic Python Unit Testing

Python includes a built-in unittest module, but pytest has become very popular due to its simplicity and powerful features.

Why Unit Test?

  • Validates that code works as expected
  • Makes refactoring safer by catching regressions
  • Serves as documentation for how your code should be used
  • Encourages modular, testable code design

pytest Framework

pytest is a more advanced testing framework that simplifies test writing:

# Simple pytest example
def test_addition():
    assert 1 + 1 == 2

Key pytest Features:

  1. Simple Assertions: Just use Python's assert statement - no need for special assertion methods.

  2. Test Discovery: Automatically finds test files and functions (named with test_ prefix).

  3. Fixtures: For setting up test environments and sharing resources between tests:

import pytest

@pytest.fixture
def example_data():
    return {'key': 'value'}

def test_with_fixture(example_data):
    assert example_data['key'] == 'value'
  1. Parameterized Tests: Test multiple input combinations easily:
@pytest.mark.parametrize("input,expected", [
    (1, 1),
    (2, 4),
    (3, 9),
])
def test_square(input, expected):
    assert input * input == expected
  1. Powerful Output: Detailed error reports and test results.

Getting Started

  1. Install pytest:
pip install pytest

  1. Create test files (named test_*.py) in your project.

  2. Write test functions (named test_*) in those files.

  3. Run tests with the command:

pytest
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