public/js/tests/debounce_test.js

export const tests = []
const t = (f) => tests.push(f)

const add = (arr, el) => arr.push(el)

// it uses the array to better test the leading and trailing edge of the time limit
// so if the leading edge is true it will execute the callback
// if the trailing edge is true it will execute the callback before returning the array
const run = (callback, { delay, count }) =>
  new Promise((r) => {
    const arr = []
    const inter = setInterval(() => callback(arr, 1), delay)
    setTimeout(() => {
      clearInterval(inter)
      r(arr.length)
    }, delay * count)
  })

t(async ({ eq }) =>
  // test with debounce wait limit inferior to wait time call (how much time we wait to the function be called again)
  // it works concurrently
  eq(
    await Promise.all([
      run(debounce(add, 50), { delay: 100, count: 5 }),
      run(debounce(add, 20), { delay: 50, count: 10 }),
    ]),
    [4, 9]
  )
)
t(async ({ eq }) =>
  // testing with wait limit superior to wait time call
  // execution on the trailing edge, after wait limit has elapsed
  eq(await run(debounce(add, 100), { delay: 50, count: 5 }), 0)
)

t(async ({ eq }) =>
  // it works concurrently
  eq(
    await Promise.all([
      run(opDebounce(add, 40), { delay: 20, count: 5 }),
      run(opDebounce(add, 40), { delay: 20, count: 2 }),
    ]),
    [0, 0]
  )
)

t(async ({ eq }) =>
  // leading edge as true
  // it works concurrently
  eq(
    await Promise.all([
      run(opDebounce(add, 200, { leading: true }), { delay: 70, count: 3 }),
      run(opDebounce(add, 100, { leading: true }), { delay: 140, count: 3 }),
    ]),
    [1, 2]
  )
)

Object.freeze(tests)