Pragmatic Unit Testing in Java with JUnit, 3rd Edition

Starting Simple

TDD is a three-part cycle:

1. Write a test that fails.
2. Get the test to pass.
3. Clean up any code added or changed in the prior two steps.

The first step of the cycle tells you to write a test describing the behavior you want to build into the system. Seek to write a test representing the smallest possible—but useful—increment to the code that already exists.

For your exercise, you’ll test-drive a small portfolio manager. Your requirements will be revealed to you incrementally as well, in batches, by your product owner Madhu. Imagine that each requirements batch was not previously considered. Your job is to deliver a solution for each incremental need to production.

You want to ensure that you can continue to accommodate new batches of ...