// The updates wire (live.go's updatesGet): each update framed as a
// 4-byte big-endian length then the bytes. A body that does not divide
// cleanly is an error rather than a short read — a client that guessed
// would be a client that silently lost the last update.
import test from 'node:test'
import assert from 'node:assert/strict'
import { parseFrames, frame } from './frames.mjs'

test('an empty body is no frames', () => {
  assert.deepEqual(parseFrames(new Uint8Array(0)), [])
})

test('frames come back in order with their exact bytes', () => {
  const a = new Uint8Array([1, 2, 3])
  const b = new Uint8Array([])
  const c = new Uint8Array([9])
  const body = new Uint8Array([...frame(a), ...frame(b), ...frame(c)])
  const got = parseFrames(body)
  assert.equal(got.length, 3)
  assert.deepEqual(Array.from(got[0]), [1, 2, 3])
  assert.deepEqual(Array.from(got[1]), [])
  assert.deepEqual(Array.from(got[2]), [9])
})

test('a length prefix is big-endian', () => {
  const body = new Uint8Array([0, 0, 1, 0, ...new Array(256).fill(7)])
  assert.equal(parseFrames(body)[0].length, 256)
})

test('a truncated frame throws rather than returning a short update', () => {
  assert.throws(() => parseFrames(new Uint8Array([0, 0, 0, 5, 1, 2])), /frame/)
  assert.throws(() => parseFrames(new Uint8Array([0, 0])), /frame/)
})