Layer Testing Skill

Orchestrate comprehensive layer testing with coverage analysis and isolated worktrees.

Isolated worktrees keep testing work separate from your working branch, preventing accidental commits to main development branches and enabling parallel testing of multiple layers.

Get Parameters

From command invocation:

Testing Request:
- Module: auth
- Layer: infrastructure
- Playbook: docs/playbook.md (optional)
- Coverage Target: 100% (optional)

From natural invocation: Ask user for module, layer, playbook path (optional), coverage target (optional).

Get Testing Strategy

If playbook provided:

bash

Read(${PLAYBOOK_PATH})

If no playbook: Ask user to choose:

<strategy_options>

Hexagonal Architecture - Domain/Application 100%, skip infra schemas
Clean Architecture - Use cases/Entities 100%, skip frameworks
Layered - Services/Logic 100%, skip DTOs/configs
Custom - I'll answer questions about what to test </strategy_options>

If user picks 1-3: Use template from skills/layer-testing/templates/

If user picks 4: Ask:

Coverage target? (100%/80%/70%)
What to test? (business logic only / all code)
What to skip? (types, schemas, mocks, configs)
Build strategy from answers

Store strategy for agent use.

Run Coverage First

Check for existing tests:

bash

find src/modules/${MODULE}/${LAYER} -name "*.test.*" -o -path "*/__tests__/*"

If NO tests: Skip to step 4

If tests exist:

Detect framework and run coverage (run these checks in parallel):

bash

if [[ -f "vitest.config.ts" ]] || grep -q "vitest" package.json; then
  pnpm test src/modules/${MODULE}/${LAYER} --coverage --reporter=json-summary
elif [[ -f "jest.config.js" ]] || grep -q "jest" package.json; then
  pnpm test -- src/modules/${MODULE}/${LAYER} --coverage --coverageReporters=json-summary
fi

Parse coverage/coverage-summary.json:

bash

TOTAL_COV=$(jq '.total.lines.pct' coverage/coverage-summary.json)

If 100% coverage:

✅ Already at 100% coverage!

Options:
1. Exit (nothing to do)
2. Verify test quality
3. Enhance tests

Choose (1-3):

If user picks 1, exit successfully.

If < 100%: Continue to Step 4

Analyze Files

Find all files:

bash

find src/modules/${MODULE}/${LAYER} -name "*.ts" ! -name "*.test.*" ! -path "*/__tests__/*"

Categorize using strategy:

Testable (matches "what to test" patterns)
Skip (matches "what to skip" patterns)

Cross-reference with coverage (if available):

Fully covered (100%)
Partially covered (<100%, extract uncovered lines)
Not tested (0% or not in coverage)

Present Analysis & Ask User

Show results:

📊 ${MODULE}/${LAYER}

Coverage: ${TOTAL_COV}% (target: ${TARGET}%)
Gap: ${GAP}%

✅ Fully Covered:
  - File1.ts (100%)

⚠️ Partially Covered:
  - File2.ts (45%, lines 10-20, 30-40 uncovered)

❌ Not Tested:
  - File3.ts (0%)

⊘ Skip:
  - schema.ts (per strategy)

Which files to test?
1. All gaps
2. Untested only
3. Partial only
4. Custom selection

Wait for user response.

Create Worktree

bash

BRANCH="test/${MODULE}-${LAYER}-coverage"
git worktree add ../worktree-${BRANCH} -b ${BRANCH}

Spawn Testing Agent

typescript

Task({
  subagent_type: 'general-purpose',
  description: 'Test ${MODULE}/${LAYER}',
  prompt: `
Test the ${LAYER} layer of ${MODULE} module.

Strategy: Read ${PLAYBOOK_PATH}
Files: ${SELECTED_FILES}
Target: ${COVERAGE_TARGET}%
Working directory: ${WORKTREE_PATH}

Follow strategy principles.
Write comprehensive tests.
Never modify production code.
Create single commit when done.

Report:
- Coverage achieved
- Tests created
- Any issues
`
})

Wait for agent completion.

Verify Results

bash

# 1. Tests pass
pnpm test ${FILES}

# 2. Coverage meets target
pnpm test ${FILES} --coverage
# Parse and verify >= target

# 3. No production code changes
git diff --name-only | grep -v test | wc -l  # Should be 0

# 4. Type check passes
pnpm typecheck

# 5. Lint passes
pnpm lint

All five gates must pass before proceeding to report.

Report

✅ Testing Complete: ${MODULE}/${LAYER}

Coverage: ${BEFORE}% → ${AFTER}% (+${DELTA}%)
Tests: ${COUNT} new tests
Files: ${FILES_TESTED}
Commit: ${COMMIT_HASH}

Quality Gates:
✅ All tests passing
✅ Coverage target met
✅ No production changes
✅ Type check passing
✅ Lint passing

Next steps:
- Review tests in worktree
- Merge: git rebase ${BRANCH}
- Or: Continue testing other layers

Search AI Tools

layer-testing

Install this agent skill to your Project

SKILL.md

Layer Testing Skill