How I Added Testing to share-my-repo Project and Learned a Lot

#testing #opensource #programming #pytest

Testing is an important part of building software, but many developers, including me, sometimes skip it. In this post, I want to share how I added tests to my Python project, the tools I used, how I set them up, and what I learned along the way.

Tools I Chose for Testing

For my project, I decided to use pytest as my main testing framework and pytest-cov for code coverage because they are widely used, easy to set up, and provide clear feedback on test results and coverage.

pytest: pytest is a popular Python testing framework. It’s easy to use, supports simple tests, and has many features like fixtures and parameterized tests.
pytest-cov: This plugin works with pytest to show which parts of your code are covered by tests. It helps you find which lines are being missed.

I also used pytest-watch (ptw) to automatically run tests whenever I make changes. This makes development faster and helps catch problems immediately.

Setting Up Testing in My Project

Install dependencies:

   pip install pytest pytest-cov pytest-watch

Project Organization

I kept the source code in src/ and tests in tests/. Each file in the source has a corresponding test file, e.g., file_processor.py has tests/test_file_processor.py.

Writing Tests

I created test classes and methods for each function. For example:

class TestNormalizePath:
    def setup_method(self):
        self.processor = FileProcessor()

    def test_normalize_path_basic(self):
        path = Path("C:\\Users\\Example\\File.TXT")
        result = self.processor._normalize_path(path)
        assert result == "c:/users/example/file.txt"

Running Tests

pytest -v  # run all tests
pytest -v tests/test_file_processor.py  # run a single test file
pytest -v tests/test_file_processor.py::TestNormalizePath::test_normalize_path_basic  # run a single test
ptw  # watch for changes and run tests automatically

Check Code Coverage

pytest --cov=src/

I also made scripts (scripts/test.sh for Linux/macOS and scripts/test.bat for Windows) so anyone can run tests and see coverage easily.

What I Learned

Think like a pessimist: Writing tests made me consider all edge cases, like empty inputs or file errors.
Found hidden bugs: I found paths that didn’t normalize correctly on Windows and cases where the code failed if a file was outside the root directory.
Small tests are better: Writing focused tests per function made debugging much easier.