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Testing Fundamentals

What Is Defect Lifecycle?

The defect lifecycle (also called the bug lifecycle) is the series of stages a defect passes through from initial discovery to final closure, typically including New, Assigned, Open, Fixed, Verified, and Closed.

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In Depth

When a tester discovers a defect, it enters the lifecycle as New. A lead or triage team reviews it and either assigns it to a developer (Assigned), rejects it as not-a-bug, or defers it. Once the developer starts working on it, it moves to Open, then Fixed when a code change is submitted. The QA team verifies the fix in the build, and if the defect no longer reproduces, it moves to Verified and finally Closed. If the fix is incomplete, it is Reopened.

A strong bug report accelerates every stage. It includes a descriptive title, environment details, precise reproduction steps, expected versus actual behavior, severity and priority, and supporting evidence (screenshots, logs, network traces). Teams that write poor bug reports waste cycles on back-and-forth clarification.

Defect triage is the process of prioritizing the backlog. Teams typically triage based on severity (impact on the user), priority (business urgency), and frequency (how many users are affected). Effective triage prevents low-impact bugs from blocking high-impact work and ensures critical issues get attention immediately.

Why Interviewers Ask About This

Interviewers ask about the defect lifecycle to assess your process maturity. Knowing the stages shows you understand not just finding bugs but managing them through resolution.

Example Scenario

A tester files a bug: "Checkout fails when cart contains more than 50 items." It is triaged as Severity-High, Priority-Medium because it affects edge-case users. The developer fixes the cart-size query, the tester verifies in staging, and the defect moves to Closed in one sprint.

Interview Tip

Go beyond listing stages. Discuss how you write effective bug reports, your approach to triage meetings, and how you handle disputes about severity versus priority.

Related Terms

Explore related glossary terms to deepen your understanding.

Test CaseA test case is a documented set of preconditions, inputs, execution steps, and expected results designed to verify that a specific feature or behavior of the application works correctly.
Exploratory TestingExploratory testing is a testing approach where the tester simultaneously learns about the system, designs tests, and executes them in real time without predefined scripts.
Regression TestingRegression testing is the practice of re-running existing tests after code changes to verify that previously working functionality has not been broken by new commits.
Acceptance CriteriaAcceptance criteria are specific, testable conditions that a user story or feature must satisfy to be considered complete and accepted by the product owner.
Quality GatesQuality gates are checkpoints in the software delivery process where predefined quality criteria must be met before work can proceed to the next stage, enforcing minimum standards at each phase.

Related Resources

Dive deeper with these related interview prep pages.

Manual Testing QuestionsSoftware Testing InterviewQA Mock Interview PracticeQA Methodology Questions

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Written by Aston Cook, Senior QA EngineerLast updated: March 2026