claude-code/src/utils/__tests__/memoize.test.ts

import { mock, describe, expect, test, beforeEach } from 'bun:test'
import { logMock } from '../../../tests/mocks/log'

// Mock log.ts to cut the bootstrap/state dependency chain
mock.module('src/utils/log.ts', logMock)

const { memoizeWithTTL, memoizeWithTTLAsync, memoizeWithLRU } = await import(
  '../memoize'
)

// ─── memoizeWithTTL ────────────────────────────────────────────────────

describe('memoizeWithTTL', () => {
  test('returns cached value on second call', () => {
    let calls = 0
    const fn = memoizeWithTTL((x: number) => {
      calls++
      return x * 2
    }, 60_000)

    expect(fn(5)).toBe(10)
    expect(fn(5)).toBe(10)
    expect(calls).toBe(1)
  })

  test('different args get separate cache entries', () => {
    let calls = 0
    const fn = memoizeWithTTL((x: number) => {
      calls++
      return x + 1
    }, 60_000)

    expect(fn(1)).toBe(2)
    expect(fn(2)).toBe(3)
    expect(calls).toBe(2)
  })

  test('cache.clear empties the cache', () => {
    let calls = 0
    const fn = memoizeWithTTL(() => {
      calls++
      return 'val'
    }, 60_000)

    fn()
    fn.cache.clear()
    fn()
    expect(calls).toBe(2)
  })

  test('returns stale value and triggers background refresh after TTL', async () => {
    let calls = 0
    const fn = memoizeWithTTL((x: number) => {
      calls++
      return x * calls
    }, 1) // 1ms TTL

    const first = fn(10)
    expect(first).toBe(10) // calls=1, 10*1

    // Wait for TTL to expire
    await new Promise(r => setTimeout(r, 10))

    // Should return stale value (10) and trigger background refresh
    const second = fn(10)
    expect(second).toBe(10) // stale value returned immediately

    // Wait for background refresh microtask
    await new Promise(r => setTimeout(r, 10))

    // Now cache should have refreshed value (calls=2 during refresh, 10*2=20)
    const third = fn(10)
    expect(third).toBe(20)
  })
})

// ─── memoizeWithTTLAsync ───────────────────────────────────────────────

describe('memoizeWithTTLAsync', () => {
  test('caches async result', async () => {
    let calls = 0
    const fn = memoizeWithTTLAsync(async (x: number) => {
      calls++
      return x * 2
    }, 60_000)

    expect(await fn(5)).toBe(10)
    expect(await fn(5)).toBe(10)
    expect(calls).toBe(1)
  })

  test('deduplicates concurrent cold-miss calls', async () => {
    let calls = 0
    const fn = memoizeWithTTLAsync(async (x: number) => {
      calls++
      await new Promise(r => setTimeout(r, 20))
      return x
    }, 60_000)

    const [a, b, c] = await Promise.all([fn(1), fn(1), fn(1)])
    expect(a).toBe(1)
    expect(b).toBe(1)
    expect(c).toBe(1)
    expect(calls).toBe(1)
  })

  test('cache.clear forces re-computation', async () => {
    let calls = 0
    const fn = memoizeWithTTLAsync(async () => {
      calls++
      return 'v'
    }, 60_000)

    await fn()
    fn.cache.clear()
    await fn()
    expect(calls).toBe(2)
  })

  test('returns stale value on TTL expiry', async () => {
    let calls = 0
    const fn = memoizeWithTTLAsync(async () => {
      calls++
      return calls
    }, 1) // 1ms TTL

    const first = await fn()
    expect(first).toBe(1)

    await new Promise(r => setTimeout(r, 10))

    // Should return stale value (1) immediately
    const second = await fn()
    expect(second).toBe(1)
  })
})

// ─── memoizeWithLRU ────────────────────────────────────────────────────

describe('memoizeWithLRU', () => {
  test('caches results by key', () => {
    let calls = 0
    const fn = memoizeWithLRU(
      (x: number) => {
        calls++
        return x * 2
      },
      x => String(x),
      10,
    )

    expect(fn(5)).toBe(10)
    expect(fn(5)).toBe(10)
    expect(calls).toBe(1)
  })

  test('evicts least recently used when max reached', () => {
    let calls = 0
    const fn = memoizeWithLRU(
      (x: number) => {
        calls++
        return x
      },
      x => String(x),
      3,
    )

    fn(1)
    fn(2)
    fn(3)
    expect(calls).toBe(3)

    fn(4) // evicts key "1"
    expect(fn.cache.has('1')).toBe(false)
    expect(fn.cache.has('4')).toBe(true)
  })

  test('cache.size returns current size', () => {
    const fn = memoizeWithLRU(
      (x: number) => x,
      x => String(x),
      10,
    )

    fn(1)
    fn(2)
    expect(fn.cache.size()).toBe(2)
  })

  test('cache.delete removes entry', () => {
    const fn = memoizeWithLRU(
      (x: number) => x,
      x => String(x),
      10,
    )

    fn(1)
    expect(fn.cache.has('1')).toBe(true)
    fn.cache.delete('1')
    expect(fn.cache.has('1')).toBe(false)
  })

  test('cache.get returns value without updating recency', () => {
    const fn = memoizeWithLRU(
      (x: number) => x * 10,
      x => String(x),
      10,
    )

    fn(5)
    expect(fn.cache.get('5')).toBe(50)
  })

  test('cache.clear empties everything', () => {
    const fn = memoizeWithLRU(
      (x: number) => x,
      x => String(x),
      10,
    )

    fn(1)
    fn(2)
    fn.cache.clear()
    expect(fn.cache.size()).toBe(0)
  })
})