CTFL-v4 Fundamentals of Testing Practice Question
A tester finds a defect and reports it. During the bug fix, the developer accidentally introduces a new issue. What testing is required to catch this?
⚠ Common exam trap
Candidates might choose confirmation testing alone, forgetting that modifying code for a bug fix can introduce unexpected side effects elsewhere.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Regression testing.
Regression testing is necessary whenever changes are made to the code. Even if a bug fix seems isolated, it can have unintended consequences in other parts of the system. By performing regression testing, the team ensures that the fix did not break existing, previously working functionality. This is a fundamental safeguard against the risks of code modification and is essential for maintaining system stability throughout the development process.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Confirmation testing.
Why it's wrong here
Confirmation testing (re-testing) only checks if the original bug has been fixed. It does not verify if the fix caused other parts of the application to break. While essential, it is insufficient on its own when code changes are involved, because it only covers the specific issue reported originally.
- ✓
Regression testing.
Why this is correct
Regression testing involves re-running existing tests to ensure that changes, such as bug fixes, have not adversely affected previously working features. It is the specific process designed to detect when a fix inadvertently introduces new defects or breaks existing functionality elsewhere in the system, maintaining overall application integrity.
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System testing.
Why it's wrong here
System testing is a broad phase focused on testing the whole integrated system. While it might uncover the new issue, it is not the most efficient way to verify a specific fix. Regression testing is the targeted approach required to ensure that the code change hasn't negatively impacted stable functionality.
- ✗
Static testing.
Why it's wrong here
Static testing involves reviewing documentation or code without executing it. While it can identify potential issues early, it cannot verify the behavior of the software after a code change. Dynamic testing, specifically regression testing, is required to detect the runtime side effects caused by the developer's new code changes.
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official ISTQB exam blueprint
This CTFL-v4 practice question is part of Courseiva's free ISTQB certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CTFL-v4 exam.