Programming Readiness: Testing and Debugging

This module supports R5 and R6, while reinforcing R1–R4. All work here is formative. Pick Java or Python and stay with it.

Specification checklist

Traced/worked example

A three-of-a-kind test expects true for three 9s but gets false:

rankCounts.put(card.rank, 1);
if (rankCounts.get(card.rank) == 3) return true;

Every put stores 1, so the count never reaches 3. The smallest repair is increment: getOrDefault(rank, 0) + 1. Rerun the three-9s test and a two-9s test.

A flowerbed loop that uses i <= flowerbed.length reads off the end. Change it to i < flowerbed.length, mark planted plots, and recheck {1, 0, 0, 0, 1} with n = 1 (true) and n = 2 (false).

Practice

Guided: For hasThreeOfAKind, write two tests first: three 9s (expected true) and two 9s (expected false). Then run the starter.

Independent: Repair hasThreeOfAKind and canPlaceFlowers using the supplied tests. Do not change expected values to hide a bug.

Java: Practice.java, PracticeTest.java, Card.java

javac Practice.java PracticeTest.java Card.java && java PracticeTest

Python: practice.py

python3 practice.py

Common mistakes

• Changing several lines before rerunning.
• Editing a test to match the buggy output.
• Planting next to an existing 1, or not marking a planted plot.

Exit guidance

For each fix, write: failing evidence, root cause, smallest revision, and which test now passes. This is practice for the typed follow-up; official Verification is scheduled separately.

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