Mastering Python - Effortlessly Running Tests with python -m doctest

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Python -m doctest

Writing a Python Module

• Become a fully fledged Python package developer by writing your first package!
• You’ll learn how to structure and write Python code that can be installed, used, and distributed just like famous packages such as NumPy and Pandas.

Utilizing Classes

• Object Oriented Programming is a staple of Python development.
• By leveraging classes and inheritance, your Python package will become a much more powerful tool for your users.

Maintainability

• You’ve now written a fully functional Python package for text analysis!
• To make maintaining your project as easy as possible, we’ll leverage best practices around concepts such as documentation and unit testing.

Documentation

• Identifying good comments
• Identifying proper docstrings
• Writing docstrings
• Readability counts
• Using good function names
• Using good variable names
• Refactoring for readability

Unit testing

• Using doctest
• Using pytest
• Documentation & testing in practice
• Documenting classes for Sphinx
• Identifying tools

Final Thoughts

• Hide Details
• Exercise

Exercise Using doctest

• We just learned about doctest, which, if you’re writing full docstrings with examples, is a simple way to minimally test your functions.
• In this exercise, you’ll get some hands-on practice testing and debugging with doctest.
• The following have all been pre-loaded in your environment: doctest, Counter, and text_analyzer.
• Note that your docstring submission must match the solution exactly.
• If you find yourself getting it wrong several times, it may be a good idea to refresh the sample code and start over.

Instructions

1. Complete the input code of the example in the docstring for sum_counters.
2. Complete the docstring example by filling in the expected output.
3. Run the testmod function from doctest to test your function’s example code.

def sum_counters(counters):
    """
    Sum the values in a dictionary of counters.

    >>> c1 = Counter(a=1, b=2, c=3)
    >>> c2 = Counter(a=2, b=3, c=4)
    >>> sum_counters([c1, c2])
    {'a': 3, 'b': 5, 'c': 7}
    """
    total = Counter()
    for counter in counters:
        total += counter
    return total

import doctest
doctest.testmod()

• Take Hint (-30 XP)

By completing the exercise and running the testmod function, you can verify if your sum_counters function works as expected.