Engineering Ideas Into Algorithms

Faisal Tahir October 15, 2025 3 min read

How to Test a Bug Fix the Right Way

How to Test a Bug Fix the Right Way: Beyond “It’s Working Now” Most people think testing a bug fix is simple: Find the bug → Developer fixes it → You recheck → Done. But that approach only scratches the surface. If you want to become an effective tester, someone who adds real value to the development cycle, you have to go deeper than just verifying that “it works now.” You need to understand what went wrong, why it went wrong, and what was changed to fix it. That’s where root cause awareness becomes the game changer. Typical Flow of a Bug Fix Here’s what usually happens in a fast-paced team: QA reports a bug. The dev takes ownership, makes a fix, and moves the ticket to “Fixed.” QA gets it back with no note on the root cause, no mention of what changed, and no explanation of potential side effects. Now QA retests using the same steps that originally caused the bug. It passes. So the tester closes it. Everything seems fine until two sprints later when a similar bug reappears elsewhere in the system. The Real Problem When you don’t know the root cause, you’re not really testing the fix — you’re just re-testing the symptom. Without knowing what was changed in the code or logic: You can’t identify regression risks. You don’t know what related modules might be impacted. You can’t design effective test cases for validation. You might verify that the specific error doesn’t show up again — but you can’t guarantee that nothing else broke in the process. A Real Example Imagine this: An API returns HTTP 500 for one user. All other users get the correct response. The bug is fixed, and QA retests with the same user — the error is gone. Test passed. But after discussing with the developer, you learn: “The error occurred only for users with a system history longer than 20 months.” That one detail changes everything. Now, as a good tester, you expand your testing scope to include: A fresh user (0 months history) A user with exactly 20 months of history A user with 21 months A user with 40 months And the user with the longest recorded history in the system You’re no longer just testing “if it works now”, you’re testing how robust the fix is and whether it scales or regresses under edge cases. Why This Matters The difference between an average tester and a great tester is the ability to turn developer feedback into testing insights. Every conversation with a developer can uncover: New risk areas Code dependencies Logic paths you didn’t know existed Data combinations that can break under real conditions When you understand the root cause, you’re better equipped to: Identify similar vulnerabilities elsewhere in the product Suggest preventive checks or assertions Strengthen regression coverage for future builds Testing without context is like shooting in the dark, you might hit the target, but you won’t know why you missed next time. The Best Practice Next time you pick up a “Fixed” ticket, don’t just retest the bug. Ask the developer: What was the root cause? What part of the code or logic was changed? What was the scope of impact? It’s not about micromanaging or questioning, it’s about aligning on quality ownership. The goal is not just to close bugs, it’s to reduce the probability of their recurrence and improve system reliability. Final Thought As testers, our job is not just to confirm functionality. It’s to understand behavior, risk, and stability. When you combine developer insight with test creativity, you transform QA from being a reactive process into a proactive safeguard for the product. The next time you test a fix, remember: “Understanding the root cause gives you the power to test smarter, not harder.” Because great testing doesn’t just find bugs, it prevents the next ones.