49Tests

An unpopular opinion: at the start you barely need tests.

A test is code that checks your code. Useful, but it has a price: time to write and time to maintain. For a project built in an evening and changing daily, that price doesn't pay off.

Where they genuinely matter, even for a beginner: anywhere money is counted, and anywhere something can be deleted. If your project takes payments or deletes data, test those two places and live calmly with the rest.

Everything else is checked simply: open it and look. It works - good.

When the time comes: when the project grows past the point where you remember all of its parts, and a change in one place starts breaking another. That's when tests become salvation. You'll recognise the moment yourself; it's hard to miss.