dd0c/products/05-aws-cost-anomaly/tests/unit/governance.test.ts

import { describe, it, expect, beforeEach } from 'vitest';
import { GovernanceEngine, FakeClock } from '../../src/governance/engine.js';

describe('GovernanceEngine', () => {
  let clock: FakeClock;
  let engine: GovernanceEngine;

  beforeEach(() => {
    clock = new FakeClock(new Date('2026-03-01').getTime());
    engine = new GovernanceEngine(clock);
  });

  it('does not promote at day 13', () => {
    const result = engine.evaluatePromotion('t1', { fpRate: 0.05, daysInCurrentMode: 13 });
    expect(result.promoted).toBe(false);
  });

  it('promotes at day 15 with low FP rate', () => {
    const result = engine.evaluatePromotion('t1', { fpRate: 0.05, daysInCurrentMode: 15 });
    expect(result.promoted).toBe(true);
    expect(result.newMode).toBe('audit');
  });

  it('does not promote at day 15 with high FP rate', () => {
    const result = engine.evaluatePromotion('t1', { fpRate: 0.15, daysInCurrentMode: 15 });
    expect(result.promoted).toBe(false);
    expect(result.reason).toContain('false-positive rate');
  });

  it('promotes at exactly day 14 with 0% FP rate', () => {
    const result = engine.evaluatePromotion('t1', { fpRate: 0, daysInCurrentMode: 14 });
    expect(result.promoted).toBe(true);
  });

  it('does not promote at exactly 10% FP rate', () => {
    const result = engine.evaluatePromotion('t1', { fpRate: 0.10, daysInCurrentMode: 20 });
    expect(result.promoted).toBe(true); // 10% is the threshold, not exceeded
  });

  it('does not promote at 10.1% FP rate', () => {
    const result = engine.evaluatePromotion('t1', { fpRate: 0.101, daysInCurrentMode: 20 });
    expect(result.promoted).toBe(false);
  });
});

describe('Panic Mode Redis Failure', () => {
  let engine: GovernanceEngine;

  beforeEach(() => {
    engine = new GovernanceEngine();
  });

  it('defaults to panic=active when Redis is unreachable', async () => {
    const fakeRedis = {
      get: async () => { throw new Error('Connection refused'); },
    };
    const result = await engine.checkPanicMode('t1', fakeRedis);
    expect(result).toBe(true); // Safe default
  });

  it('returns false when panic is not set', async () => {
    const fakeRedis = { get: async () => null };
    const result = await engine.checkPanicMode('t1', fakeRedis);
    expect(result).toBe(false);
  });

  it('returns true when panic is active', async () => {
    const fakeRedis = { get: async () => '1' };
    const result = await engine.checkPanicMode('t1', fakeRedis);
    expect(result).toBe(true);
  });
});