Test-driven design can be daunting at first. This book presents a moderately complex task - write a program that can read a mathematical expression like 2 + 3 * 5 and return its result. The author explains each step with both tests and production code until the program can handle decimal numbers, multiple levels of parentheses and even symbols (like in x + 3).This is a code-heavy, hands-on book; just reading it without writing the code yourself might not provide the full benefit.About the Author: Marcel Popescu discovered computers when he was twelve years old. (According to his daughters, dinosaurs were still alive back then.) It was the first time he did not abandon a hobby and he's still unable to escape the thrill of writing code. He has worked with languages ranging from COBOL and FORTRAN to JavaScript, but right now his favorite language is C#.