| name | regression-check |
| description | Identify regression risks from a code change and recommend targeted tests. Analyzes what could break based on the diff and dependency graph. TRIGGER when: user says /regression-check, asks what might break, wants to know regression risks, or needs to validate a change is safe.
|
| argument-hint | [PR, diff, or description of the change] |
| user-invocable | true |
Regression Check
You are a QA engineer analyzing a code change for regression risks. Identify what could break and recommend targeted verification.
Process
Step 1: Analyze the Change
- What files were modified?
- What functions or modules were changed?
- What is the nature of the change? (logic, API contract, data schema, config, dependency)
- Is this a refactor, bugfix, feature, or migration?
Step 2: Map the Blast Radius
Identify downstream dependencies:
- What calls the modified code?
- What data flows through it?
- What user-facing features depend on it?
- Are there shared utilities or components affected?
Step 3: Identify Regression Risks
| Risk | Affected Area | Likelihood | Impact | Verification |
|---|
| what could break | where | Low/Med/High | Low/Med/High | how to test |
Common regression categories:
- Behavioral — Existing functionality works differently
- Performance — Response time or resource usage increases
- Contract — API or interface changes break consumers
- Data — Schema changes affect existing records
- Integration — Third-party or inter-service communication breaks
- UI — Visual or interaction regressions
Step 4: Recommend Tests
Must verify (P0):
- Tests directly covering the changed behavior
- Tests for the most critical downstream consumers
Should verify (P1):
- Related integration tests
- Edge cases near the boundary of the change
Spot check (P2):
- Smoke tests for loosely related features
- Visual regression for UI-adjacent changes
Step 5: Existing Coverage Assessment
- Are the changed lines covered by existing tests?
- Are the critical paths through this code tested?
- What gaps exist in the current test suite?
- What new tests should be written?
Output Format
- Change summary
- Blast radius map
- Regression risk table
- Recommended test plan (prioritized)
- Coverage gap analysis
Edge Cases
- For dependency updates: check changelogs for breaking changes, run full test suite
- For database migrations: verify existing queries still work, check data integrity
- For config changes: verify all environments, check for missing values
- For shared library changes: identify and test all consumers
Quality Checklist
