AP CSP Practice: Testing & Program Development

Big Idea 1: Creative Development
Day 1 Practice • AP CSP Daily Question
🎯 Focus: Collaboration in Program Development

Practice Question

A team of students is developing a mobile app to help users track their daily water intake. During the development process, one team member notices that the app sometimes crashes when users enter very large numbers.
Which of the following actions is MOST likely to help identify and fix this issue?
What This Tests: Big Idea 1 covers the collaborative and iterative nature of program development, including how testing helps identify and fix errors.

Why B is Correct

Testing with a variety of inputs, especially edge cases, is a fundamental practice in program development. Edge cases are extreme or unusual inputs that might cause unexpected behavior.

When testing, developers should try:

  • Typical expected inputs
  • Boundary values (minimum and maximum allowed)
  • Invalid inputs (negative numbers, letters, etc.)
  • Edge cases (very large numbers, empty inputs, special characters)

Common Mistakes

Mistake: Answer A - Removing the feature

Removing functionality to avoid bugs reduces the usefulness of the program. Good development fixes issues rather than removing features.

Mistake: Answer C - Asking users to behave

You cannot control user behavior. Programs should handle unexpected inputs gracefully rather than relying on users to follow rules.

Mistake: Answer D - Starting over

Rewriting from scratch is rarely necessary and wastes work already done. Iterative development means fixing specific issues, not starting over.

💡 AP Exam Tip

The AP CSP exam frequently asks about the iterative development process: design → develop → test → refine → repeat. Testing with diverse inputs is a key part of this cycle.

Difficulty: Easy • Time: 1-2 minutes • Topic: 1.2 Program Development

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