What steps do you take to check and ensure the quality of your code?

To check and ensure the quality of Python code, I usually follow these steps:

• Static code analysis using tools like pylint, flake8, or mypy (for type checking).
• Test coverage: writing unit tests with unittest or pytest to verify the correctness of functions and classes.
• Code review: participating in code review processes with colleagues to identify errors and improve readability.
• Code formatting using black or autopep8 to maintain a consistent style.
• Local testing and running code in different scenarios to ensure there are no errors.

Example of a simple test with pytest:

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

def test_add():
    assert add(2, 3) == 5
    assert add(-1, 1) == 0

This approach helps maintain the quality and reliability of the code.