Best Practices for Writing Doctests

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Alright! You’ve heard of unit tests, but have you ever wondered what the ***** doctests are? Well, let me tell ya they’re like your favorite pair of sweatpants: comfortable, reliable, and always there to catch any errors in your code. But how can we write these magical creatures called doctests? Time to get going with some best practices!

To begin with, what are doctests exactly? Doctests are a type of test that allow you to include examples directly within the docstring of your function or class. They look like regular Python code snippets but with an added `>` prompt at the beginning. Here’s an example:

# This function adds two numbers together and returns their sum.
def add_numbers(x, y):
    """Add two numbers together and return their sum.

    > add_numbers(2, 3)
    5
    """
    # The function takes in two parameters, x and y, and returns their sum.
    # The doctest is an example of how the function can be used and what the expected output should be.
    return x + y

Now that we know what doctests are, some best practices for writing them:

1. Keep it simple Doctests should be easy to read and understand. Avoid using complex examples or overly long explanations in your docstrings. Stick to one example per line if possible.

2. Use clear variable names Variable names should be descriptive and easy to remember. Don’t use abbreviated or obscure names that might confuse someone reading the doctest.

3. Test edge cases Make sure your doctests cover all possible scenarios, including edge cases. This will help you catch any errors or unexpected behavior in your code.

4. Use assert statements Doctests should include `assert` statements to ensure that the output matches what is expected. If the output doesn’t match, the test will fail and you can easily identify where the error occurred.

5. Keep it consistent Make sure all of your doctests follow a consistent format. This makes them easier to read and understand, as well as easier to maintain over time.

6. Use comments sparingly Comments in doctests should be used sparingly and only when necessary. They can clutter up the example code and make it harder to see what’s actually being tested.

7. Test for errors Doctests should also include examples of how your function or class handles errors. This will help you catch any unexpected behavior in those cases as well.

8. Use doctest with caution While doctests are a great tool, they shouldn’t be used as the only form of testing for your code. Make sure to also include unit tests and other forms of testing to ensure that your code is thoroughly tested.

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