The whole point of testing in development is so you don't write some new code that ends up affecting other code, causing it to fail or otherwise do something unexpected. You write some code, then you write a test to ensure the code you write does what you expect it to (you might even write the test first!). It should pass right when you create the test, which can make it seem like a weird waste of time. But there the test will set, ready in waiting to catch any new code that interferes.
- Guard Test
- Capybara Acceptance test framework for web applications
- Travis CI