Class 3 Objectives

KNOW:

• that the Racket function check-expect can be used to automate testing
• that tests should be written before the function is defined
• that if is the way to ask a true/false question in a Racket program
• that Racket has a Boolean data type to represent true/false values

BE ABLE TO:

• write test cases for a function using check-expect
• write a Racket program that makes a decision using if

Vocabulary: predicate, test case

Sample Exam Question:

Write a Racket function called sign that consumes a number, and returns one of the words positive or negative, depending on the sign of the number (consider 0 a positive number). For example,

(sign -2)

would return "negative"

Comment your function with a signature and purpose, and write a set of test cases for your function.