e29: PayPal eCommerce test coverage

In this live code session, we switched the payment processor for an e-commerce site from Braintree to PayPal. We tackled testing the new PayPal integration, fixing issues, and refactoring tests to support the new system. We removed outdated models and code for donations and subscriptions, revamped error handling for PayPal API exceptions, and added constants to clean up the code. Logging was integrated for better debugging, and tests were run frequently to catch any breaking changes. The code was committed incrementally and further refactoring was done to improve code quality. The session was challenging due to the need for frequent debugging and ensuring test coverage, but by the end, tests were passing with the new PayPal integration in place. ... https://www.youtube.com/watch?v=jPPFAH6FRrw