Use pytest + coverage

[applied-mathematician]

Thank you for submitting this pull request! We appreciate you spending the time to work on these changes.

What is the motivation?

Improve testing strategy, especially checking code coverage, before working on some src code changes.

Type of Change

• 📚 Examples / docs / tutorials / dependencies update
• 🔧 Bug fix (non-breaking change which fixes an issue)
• 🥂 Improvement (non-breaking change which improves an existing feature)
• 🚀 New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to change)
• 🔐 Security fix

What does this change do?

Ports the testing strategy from the class-based unittest style to using pytest. It also adds the tool coverage in order to monitor test coverage.

What is your testing strategy?

Run the test script, or simply uv run pytest. We should aim for increasing test coverage.

Is this related to any issues?

No

Have you read the Contributing Guidelines?

• I have read the Contributing Guidelines

[maxwellflitton]

@applied-mathematician thanks for the pull request it's passing all the tests