Writing Unit Tests for Improved Code Reliability in Python

{
  "title": "Writing Unit Tests for Improved Code Reliability in Python",
  "description": "Explore how to write effective unit tests in Python using frameworks like unittest and pytest to ensure your code behaves as expected.",
  "category": "Python Cursor Rules",
  "rules": [
    {
      "name": "Use Descriptive Test Names",
      "description": "Assign meaningful and descriptive names to your test functions to clearly convey their purpose, enhancing readability and maintainability.",
      "example": "def test_calculate_discount_for_loyal_customer():"
    },
    {
      "name": "Test One Aspect per Function",
      "description": "Each test function should focus on a single behavior or functionality to simplify debugging and ensure clarity.",
      "example": "def test_add_with_positive_numbers():\n    assert add(2, 3) == 5"
    },
    {
      "name": "Follow the Arrange-Act-Assert (AAA) Pattern",
      "description": "Structure your tests into three phases: Arrange (setup), Act (execute), and Assert (verify) to improve organization and readability.",
      "example": "def test_add_numbers():\n    # Arrange\n    a = 5\n    b = 7\n    # Act\n    result = a + b\n    # Assert\n    assert result == 12"
    },
    {
      "name": "Isolate Tests with Mocking",
      "description": "Use mocking to replace external dependencies, ensuring that unit tests are isolated and focused solely on the code under test.",
      "example": "from unittest.mock import Mock\n\ndef test_external_api_call():\n    # Arrange\n    mock_api = Mock()\n    mock_api.get_data.return_value = {\"id\": 1, \"name\": \"Test\"}\n    # Act\n    result = mock_api.get_data()\n    # Assert\n    assert result == {\"id\": 1, \"name\": \"Test\"}"
    },
    {
      "name": "Use Fixtures for Setup and Teardown",
      "description": "Utilize fixtures to manage setup and teardown processes, promoting code reuse and reducing redundancy in test cases.",
      "example": "import pytest\n\n@pytest.fixture\ndef sample_data():\n    return [1, 2, 3, 4]\n\ndef test_sum(sample_data):\n    assert sum(sample_data) == 10"
    },
    {
      "name": "Test Edge and Boundary Cases",
      "description": "Ensure your tests cover edge cases and boundary conditions to identify potential issues in extreme scenarios.",
      "example": "import pytest\n\ndef test_division_by_zero():\n    with pytest.raises(ZeroDivisionError):\n        result = 1 / 0"
    },
    {
      "name": "Keep Tests Small and Independent",
      "description": "Write tests that are concise and do not depend on the state or outcome of other tests to maintain reliability and ease of maintenance.",
      "example": "def test_functionality_a():\n    assert functionality_a() == expected_result_a\n\ndef test_functionality_b():\n    assert functionality_b() == expected_result_b"
    },
    {
      "name": "Run Tests Frequently",
      "description": "Incorporate testing into your development workflow by running tests frequently to catch issues early and ensure code stability.",
      "example": "ptw  # Automatically runs tests on file changes"
    },
    {
      "name": "Aim for Meaningful Test Coverage",
      "description": "Strive for high test coverage by testing critical and complex paths in your code, using tools like coverage.py to measure and improve coverage.",
      "example": "coverage run -m pytest\ncoverage report"
    },
    {
      "name": "Document Your Tests",
      "description": "Add comments or docstrings to explain complex test scenarios, aiding in understanding and future maintenance.",
      "example": "# Test ensuring VIP customers receive a 20% discount\ndef test_vip_customer_discount():\n    ..."
    }
  ]
}