Pragmatic Unit Testing in Java with JUnit, 3rd Edition

Extracting a New Class

The Profile class defines two responsibilities:

• Track information about a profile.
• Determine whether and to what extent a set of criteria matches a profile.

To improve your system’s design, you’ll split responsibilities into two classes, each small and adherent to the SRP. To do so, you’ll extract the code related to the profile-matching behavior to another class, Matcher. As with all refactoring, you’ll take an incremental path—make a small change and then run the tests to make sure they still pass.

For your first change, move the calculateScore logic into Matcher. Start by changing the code in matches to declare your intent: rather than call calculateScore directly from matches, construct a new Matcher object with the ...