Agent Skills: Test Isolation & Anti-Patterns Auditor (L3 Worker)

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Test Isolation & Anti-Patterns Auditor (L3 Worker)

Specialized worker auditing test isolation and detecting anti-patterns.

Purpose & Scope

• Worker in ln-630 coordinator pipeline
• Audit Test Isolation (Category 5: Medium Priority)
• Audit Anti-Patterns (Category 6: Medium Priority)
• Check determinism (no flaky tests)
• Calculate compliance score (X/10)

Inputs (from Coordinator)

Receives contextStore with isolation checklist, anti-patterns catalog, test file list.

Workflow

1. Parse context
2. Check isolation for 6 categories
3. Check determinism
4. Detect 6 anti-patterns
5. Collect findings
6. Calculate score
7. Return JSON

Audit Rules: Test Isolation

1. External APIs

Good: Mocked (jest.mock, sinon, nock) Bad: Real HTTP calls to external APIs

Detection:

• Grep for axios.get, fetch(, http.request without mocks
• Check if test makes actual network calls

Severity: HIGH

Recommendation: Mock external APIs with nock or jest.mock

Effort: M

2. Database

Good: In-memory DB (sqlite :memory:) or mocked Bad: Real database (PostgreSQL, MySQL)

Detection:

• Check DB connection strings (localhost:5432, real DB URL)
• Grep for beforeAll(async () => { await db.connect() }) without :memory:

Severity: MEDIUM

Recommendation: Use in-memory DB or mock DB calls

Effort: M-L

3. File System

Good: Mocked (mock-fs, vol) Bad: Real file reads/writes

Detection:

• Grep for fs.readFile, fs.writeFile without mocks
• Check if test creates/deletes real files

Severity: MEDIUM

Recommendation: Mock file system with mock-fs

Effort: S-M

4. Time/Date

Good: Mocked (jest.useFakeTimers, sinon.useFakeTimers) Bad: new Date(), Date.now() without mocks

Detection:

• Grep for new Date() in test files without useFakeTimers

Severity: MEDIUM

Recommendation: Mock time with jest.useFakeTimers()

Effort: S

5. Random

Good: Seeded random (Math.seedrandom, fixed seed) Bad: Math.random() without seed

Detection:

• Grep for Math.random() without seed setup

Severity: LOW

Recommendation: Use seeded random for deterministic tests

Effort: S

6. Network

Good: Mocked (supertest for Express, no real ports) Bad: Real network requests (localhost:3000, binding to port)

Detection:

• Grep for app.listen(3000) in tests
• Check for real HTTP requests

Severity: MEDIUM

Recommendation: Use supertest (no real port)

Effort: M

Audit Rules: Determinism

1. Flaky Tests

What: Tests that pass/fail randomly

Detection:

• Run tests multiple times, check for inconsistent results
• Grep for setTimeout, setInterval without proper awaits
• Check for race conditions (async operations not awaited)

Severity: HIGH

Recommendation: Fix race conditions, use proper async/await

Effort: M-L

2. Time-Dependent Assertions

What: Assertions on current time (expect(timestamp).toBeCloseTo(Date.now()))

Detection:

• Grep for Date.now(), new Date() in assertions

Severity: MEDIUM

Recommendation: Mock time

Effort: S

3. Order-Dependent Tests

What: Tests that fail when run in different order

Detection:

• Run tests in random order, check for failures
• Grep for shared mutable state between tests

Severity: MEDIUM

Recommendation: Isolate tests, reset state in beforeEach

Effort: M

4. Shared Mutable State

What: Global variables modified across tests

Detection:

• Grep for let globalVar at module level
• Check for state shared between tests

Severity: MEDIUM

Recommendation: Use beforeEach to reset state

Effort: S-M

Audit Rules: Anti-Patterns

1. The Liar (Always Passes)

What: Test with no assertions or trivial assertion (expect().toBeTruthy())

Detection:

• Count assertions per test
• If 0 assertions or only toBeTruthy() → Liar

Severity: HIGH

Recommendation: Add specific assertions or delete test

Effort: S

Example:

• BAD (Liar): Test calls createUser() but has NO assertions — always passes even if function breaks
• GOOD: Test calls createUser() and asserts user.name equals 'Alice', user.id is defined

2. The Giant (>100 lines)

What: Test with >100 lines, testing too many scenarios

Detection:

• Count lines per test
• If >100 lines → Giant

Severity: MEDIUM

Recommendation: Split into focused tests (one scenario per test)

Effort: S-M

3. Slow Poke (>5 seconds)

What: Test taking >5 seconds to run

Detection:

• Measure test duration
• If >5s → Slow Poke

Severity: MEDIUM

Recommendation: Mock external deps, use in-memory DB, parallelize

Effort: M

4. Conjoined Twins (Unit test without mocks = Integration)

What: Test labeled "Unit" but not mocking dependencies

Detection:

• Check if test name includes "Unit"
• Verify all dependencies are mocked
• If no mocks → actually Integration test

Severity: LOW

Recommendation: Either mock dependencies OR rename to Integration test

Effort: S

5. Happy Path Only (No error scenarios)

What: Only testing success cases, ignoring errors

Detection:

• For each function, check if test covers error cases
• If only positive scenarios → Happy Path Only

Severity: MEDIUM

Recommendation: Add negative tests (error handling, edge cases)

Effort: M

Example:

• BAD (Happy Path Only): Test only checks login() with valid credentials, ignores error scenarios
• GOOD: Add negative test that verifies login() with invalid credentials throws 'Invalid credentials' error

6. Framework Tester (Tests framework behavior)

What: Tests validating Express/Prisma/bcrypt (NOT our code)

Detection:

• Already detected by ln-631-test-business-logic-auditor
• Cross-reference findings

Severity: MEDIUM

Recommendation: Delete framework tests

Effort: S

Scoring Algorithm

MANDATORY READ: Load shared/references/audit_scoring.md for unified scoring formula.

Severity mapping:

• Flaky tests, External API not mocked, The Liar → HIGH
• Real database, File system, Time/Date, Network, The Giant, Happy Path Only → MEDIUM
• Random without seed, Order-dependent, Conjoined Twins → LOW

Output Format

Return JSON to coordinator (flat findings array):

{
  "category": "Isolation & Anti-Patterns",
  "score": 6,
  "total_issues": 18,
  "critical": 0,
  "high": 5,
  "medium": 10,
  "low": 3,
  "checks": [
    {"id": "api_isolation", "name": "API Isolation", "status": "failed", "details": "2 tests make real HTTP calls"},
    {"id": "db_isolation", "name": "Database Isolation", "status": "warning", "details": "1 test uses real PostgreSQL"},
    {"id": "fs_isolation", "name": "File System Isolation", "status": "passed", "details": "All FS calls mocked"},
    {"id": "time_isolation", "name": "Time Isolation", "status": "passed", "details": "All Date/Time mocked"},
    {"id": "flaky_tests", "name": "Flaky Tests", "status": "failed", "details": "3 race conditions detected"},
    {"id": "anti_patterns", "name": "Anti-Patterns", "status": "warning", "details": "2 Liars, 1 Giant found"}
  ],
  "findings": [
    {
      "severity": "HIGH",
      "location": "user.test.ts:45-52",
      "issue": "External API not mocked — test makes real HTTP call to https://api.github.com",
      "principle": "Test Isolation / External APIs",
      "recommendation": "Mock external API with nock or jest.mock",
      "effort": "M"
    },
    {
      "severity": "HIGH",
      "location": "async.test.ts:28-35",
      "issue": "Flaky test (race condition) — setTimeout without proper await",
      "principle": "Determinism / Race Condition",
      "recommendation": "Fix race condition with proper async/await",
      "effort": "M"
    },
    {
      "severity": "HIGH",
      "location": "user.test.ts:45",
      "issue": "Anti-pattern 'The Liar' — test 'createUser works' has no assertions",
      "principle": "Anti-Patterns / The Liar",
      "recommendation": "Add specific assertions or delete test",
      "effort": "S"
    },
    {
      "severity": "MEDIUM",
      "location": "db.test.ts:12",
      "issue": "Real database used — test connects to localhost:5432 PostgreSQL",
      "principle": "Test Isolation / Database",
      "recommendation": "Use in-memory SQLite (:memory:) or mock DB",
      "effort": "L"
    },
    {
      "severity": "MEDIUM",
      "location": "order.test.ts:200-350",
      "issue": "Anti-pattern 'The Giant' — test 'order flow' is 150 lines (>100)",
      "principle": "Anti-Patterns / The Giant",
      "recommendation": "Split into focused tests (one scenario per test)",
      "effort": "M"
    },
    {
      "severity": "MEDIUM",
      "location": "payment.test.ts",
      "issue": "Anti-pattern 'Happy Path Only' — only success scenarios, no error tests",
      "principle": "Anti-Patterns / Happy Path Only",
      "recommendation": "Add negative tests for error handling",
      "effort": "M"
    }
  ]
}

Note: Findings are flattened into single array. Use principle field prefix (Test Isolation / Determinism / Anti-Patterns) to identify issue category.

Critical Rules

• Do not auto-fix: Report only
• Effort realism: S = <1h, M = 1-4h, L = >4h
• Flat findings: Merge isolation + determinism + anti-patterns into single findings array, use principle prefix to distinguish
• Cross-reference ln-631: Framework Tester anti-pattern (Rule 6) references ln-631 findings — do not duplicate
• Context-aware: Supertest with real Express app is acceptable for integration tests

Definition of Done

• contextStore parsed (isolation checklist, anti-patterns catalog, test file list)
• All 3 audit groups completed:
  • Isolation (6 categories: APIs, DB, FS, Time, Random, Network)
  • Determinism (4 checks: flaky, time-dependent, order-dependent, shared state)
  • Anti-patterns (6 checks: Liar, Giant, Slow Poke, Conjoined Twins, Happy Path, Framework Tester)
• Findings collected with severity, location, effort, recommendation
• Score calculated per shared/references/audit_scoring.md
• JSON returned to coordinator

Reference Files

• Audit scoring formula: shared/references/audit_scoring.md
• Audit output schema: shared/references/audit_output_schema.md

Version: 3.0.0 Last Updated: 2025-12-23