Pragmatic Unit Testing in Java with JUnit, 3rd Edition

Moving On to a One-Based Test: Something’s Happening!

Your zero-based test saved your bacon. Maybe a one-based test can do the same? Write a test that adds one and only one credit score:

utj3-credit-history/04/src/test/java/credit/ACreditHistory.java

@Test
void withOneRatingHasEquivalentMean() {
   var creditHistory = new CreditHistory();
   creditHistory.add(new CreditRating(780));
   var result = creditHistory.arithmeticMean();
   assertEquals(780, result);
}

You might have quickly put that test in place by duplicating the zero-based test, adding a line to call creditHistory.add(), and changing the assertion.

Your new test passes. Are you done with it? No. Two critical steps remain:

1. Ensure you’ve seen it fail.
2. Clean it up.

Making It ...