Testing and coding style:

Why should one test the code? What is a unit test? What is test-driven development? Say you have a function sine(x: float) -> float: How would you test the feature? How would you handle user error? What are parameterized tests? What do you have to watch out for when testing that two numbers are equal? Is there a difference if we compare integers and floating-point numbers? What is meant by the term coding style? What is meant by documentation in programming?

Thank you!