Defect Life Cycle: From Discovery to Resolution
A 2025-ready playbook for bug intake, triage, prioritization, fixing, verification, and closure — with templates, SLAs, RACI, and metrics that keep teams aligned.
Defects are inevitable; chaos is optional. A clear, enforced Defect Life Cycle (DLC) turns noisy bug lists into fast, predictable delivery. This guide covers the end-to-end path—from discovery to triage, prioritization, fixing, verification, and closure—plus templates, SLAs, and metrics that help teams ship confidently.
Want a broader 2025 playbook (planning, automation, non-functional testing, CI/CD gates)? See Software Testing Best Practices: Complete Guide for 2025.
The Defect Life Cycle: 10 Phases
| # | Phase | Goal | Key Outputs |
|---|---|---|---|
| 1 | Discovery | Detect an issue (QA, dev, user, monitoring) | Initial evidence (steps, logs, screenshots) |
| 2 | Intake | Log a complete, reproducible ticket | Standardized bug report with environment & impact |
| 3 | Triage | Decide severity/priority, assign owner | S/P set, target release, labels, links |
| 4 | Analysis | Localize root cause; estimate fix | Root cause notes, proposed fix, risk flags |
| 5 | Fix In Progress | Implement change, tests, docs | Linked PR, unit/contract tests, notes |
| 6 | Code Review | Peer verification and guardrails | Approved PR; risk checklist |
| 7 | Merged/Build | Get into a candidate build | Build ID, changelog, deployment plan |
| 8 | QA Verification | Reproduce → verify fix; run regression | Pass/Fail on fix + affected areas |
| 9 | Release | Deploy to target env; monitor | Release notes, monitoring checks |
| 10 | Closure & RCA | Close, tag learnings, update tests | RCA doc, test suite updates, metrics |
Intake: What a Good Bug Report Looks Like
Required Fields
- Title: Concise symptom + area (e.g., “Checkout: tax miscalc on EU orders”).
- Environment: build/branch, device/OS/browser, region, feature flag state.
- Steps to Reproduce: minimal, deterministic.
- Expected vs Actual: observable behaviors, not implementation.
- Evidence: screenshots/har logs/server logs, IDs.
- Impact: user/business risk; frequency.
Nice to Have
- Suspected area (module/service/PR).
- Workarounds.
- Link to requirement/test case/monitor alert.
- Data set or fixture used.
Tip: Save a bug template in your tracker (or use a shared template in TestScope Pro for consistent intake). For broader testing patterns, visit Software Testing Best Practices: Complete Guide for 2025.
Triage: Severity vs Priority, SLAs & Ownership
Severity (S) — impact on the system/user
- S1 Critical: outage/data loss/security breach.
- S2 High: core flow broken; no workaround.
- S3 Medium: significant degradation; workaround exists.
- S4 Low: cosmetic/minor edge.
Priority (P) — when to fix
- P0: fix now, block release.
- P1: fix in current sprint/release.
- P2: backlog; schedule soon.
- P3: opportunistic/icebox.
Sample SLA Targets
| Class | Time to Triage | Time to Fix (Target) | Notes |
|---|---|---|---|
| S1/P0 | < 30 min | < 4–8 hrs | Incident process; hotfix allowed |
| S2/P1 | < 1 biz hr | 1–2 days | Blocker for release |
| S3/P1–P2 | < 1 biz day | 3–5 days | Plan in sprint |
| S4/P2–P3 | < 2 biz days | Backlog | Bundle by area |
Track SLA adherence and time-in-state on dashboards; alert on breaches. (TestScope Pro surfaces these metrics alongside defect trends.)
Workflow States & Transitions (Jira/Azure/YouTrack)
Use explicit, minimal states that map to how your team actually works.
| State | Entry Condition | Exit/Transition | Who Drives |
|---|---|---|---|
| New | Bug logged; required fields filled | → Triage | QA/Reporter |
| Triage | Severity/priority pending | → Backlog / → In Progress / → Needs Info | QA Lead + Dev Lead + PM |
| Needs Info | Missing repro/evidence | → Triage (when updated) | Reporter |
| In Progress | Owner assigned; fix started | → Code Review | Developer |
| Code Review | PR open | → Ready for QA | Peers |
| Ready for QA | Build available with change | → Verified / → Reopen | QA |
| Verified | Fix works; regression pass | → Release / → Closed | QA |
| Release | Included in deploy | → Closed | Release Eng |
| Closed | In prod; no outstanding tasks | — | QA/PM |
Add “Duplicate,” “Won’t Fix,” “As Designed” as resolutions, not states. Export CSV/JSON or sync to your tracker as needed.
Fix, Verification & Regression
Developer Checklist
- Local repro; failing test (when feasible).
- Fix + unit/contract tests; update docs.
- Risk notes for QA (areas to regress).
- Link PR & commits to the ticket.
QA Verification
- Verify fix on the same build/branch indicated.
- Regression: nearest neighbors + critical paths.
- Artifacts: screenshots/har; pass/fail notes.
- Promote to Release or Reopen with evidence.
Duplicates, “As Designed,” Won’t Fix & Reopen
- Duplicate: Link to canonical ticket; keep context (reporter still subscribed).
- As Designed: Add product decision link; consider UX improvement task.
- Won’t Fix: Record rationale (cost/benefit, roadmap); label for trend review.
- Reopen: Same symptoms reappear → Reopen with fresh evidence and build ID.
Non-Functional & Production Defects
Non-Functional (perf, security, a11y, reliability)
- Attach baseline numbers and thresholds to tickets.
- Link to pipeline jobs (k6, DAST/SAST, a11y smoke).
- Track flake rate and perf regressions as defects with trends.
Production Escapes
- Open as S1/S2 with incident ID.
- RCA within 5 biz days; list prevention tasks.
- Update tests/alerts/feature flags; track MTTR.
For modern non-functional patterns to prevent defects earlier, see Software Testing Best Practices: Complete Guide for 2025.
Metrics That Matter
| Metric | Why It Matters | Good Use |
|---|---|---|
| Defect arrival vs departure rate | Flow balance | Spot mounting backlog early |
| MTTD / MTTR | Time to detect/resolve | Shorter cycles, lower cost |
| Escape rate | User-felt quality | Invest upstream: tests/alerts |
| Reopen rate | Fix quality | Improve verification & PR review |
| Flake rate | Signal quality | Quarantine & fix cadence |
| Time in state | Bottlenecks | Remove review/QA constraints |
TestScope Pro tracks time-in-state, SLA breaches, and reopen trends so teams can tune the process with evidence.
RACI: Who Does What
| Phase | R | A | C | I |
|---|---|---|---|---|
| Intake | Reporter/QA | QA Lead | Dev Lead | PM |
| Triage | QA Lead | QA Manager | Dev Lead, PM | Stakeholders |
| Fix | Developer | Eng Manager | QA | PM |
| Verification | QA | QA Lead | Dev | PM |
| Release | Release Eng | Eng Manager | QA/PM | All |
| Closure & RCA | QA + Dev | QA Manager | PM, Security | All |
Templates & Checklists
Bug Report (Tracker Template)
- Title: [Area] Symptom
- Build/Env: branch, build ID, region, feature flags
- Steps to Reproduce: …
- Expected: …
- Actual: …
- Evidence: screenshot(s), HAR, logs (IDs)
- Impact: user/business risk, frequency
- Labels: module, platform, release
- Links: requirement, test case, PR/commit (when known)
Triage Checklist
- Repro confirmed; environment consistent
- Severity & priority set with PM/Dev
- Owner assigned; target release decided
- Related tickets/duplicates linked
- Non-functional/security implications noted
Verification Checklist
- Fix verified on stated build/env
- Regression on nearest neighbors & critical paths
- Automation updated (if applicable)
- Evidence attached; ticket resolution set
Common Anti-Patterns (and Fixes)
- Vague titles/descriptions: Enforce a template; block “Ready for Dev” without repro steps.
- Severity creep: Define severity with examples; require PM sign-off for P0/P1.
- Stale “Needs Info” bugs: Auto-close after N days with reminder; dashboards for reporters.
- Verify on wrong build: Always capture build ID; QA verifies on that build or later.
- Regression after “hot” fixes: Create a follow-up regression task; schedule in next build.
- Lost learnings: Add a simple RCA note field; tag pattern (e.g., “contract-drift”).
Conclusion & Next Steps
- Adopt a minimal, explicit workflow and enforce required fields.
- Separate severity (impact) from priority (urgency); add SLAs.
- Instrument metrics that drive action (reopen rate, time-in-state, escapes).
- Close the loop with RCA and test/monitoring updates.
For patterns that reduce defects upstream (planning, automation, non-functional baselines, CI/CD gates), read Software Testing Best Practices: Complete Guide for 2025.
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