Why finding a bug in dev costs $10 and finding it in prod costs $10,000.
Author:Sambath Kumar Natarajan(Connect)Version:1.0
Shift-Left Testing: The Economic Imperative
The Cost of Defect by Phase
The "NIST Rule of 10" states that the cost of fixing a bug increases 10x at each stage of the SDLC.
| Stage | Cost to Fix | Why? |
|---|---|---|
| Requirements | $1 (Minutes) | "Oh, we misunderstood the tax law." -> Update Issue Tracker ticket. |
| Coding (IDE) | $10 (Minutes) | Linter catches typo. |
| Integration | $100 (Hours) | CI build breaks. Developer context switch. |
| QA | $1,000 (Days) | QA opens ticket. Repro steps. Triage meeting. Fix. Re-verify. |
| Production | $10,000+ (Weeks) | Hotfix. Data corruption cleanup. PR apology. Customer Churn. |
Shift-Left is not "Developers do QA"
It means Validation moves upstream.
- Contract Testing (Pact): Validate API schemas before writing implementation.
- Ephemerals: Every PR gets a full environment. QA happens during code review, not after merge.
- TDD: Write the test to define the requirement.
The Cultural Shift
Shift-Left fails when Management treats it as a cost-cutting measure ("Fire the QAs!"). Reality: You need QAs to become Quality Engineers. They write the automation that Developers run locally.
- Old Role: Find bugs manually.
- New Role: Build the safety net so Developers can't merge bugs.