20-promise-all.ts

/**
 * 20 - Promise.all
 *
 * Type the function `PromiseAll` that accepts an array of PromiseLike objects,
 * the returning value should be `Promise<T>` where `T` is the resolved result array.
 *
 * ```ts
 * const promise1 = Promise.resolve(3);
 * const promise2 = 42;
 * const promise3 = new Promise<string>((resolve, reject) => {
 *   setTimeout(resolve, 100, 'foo');
 * });
 *
 * // expected to be `Promise<[number, 42, string]>`
 * const p = PromiseAll([promise1, promise2, promise3] as const)
 * ```
 */

/* _____________ Your Code Here _____________ */

declare function PromiseAll<T extends any[]>(
  values: readonly [...T]
): Promise<{ [Key in keyof T]: Awaited<T[Key]> }>;

/* _____________ Test Cases _____________ */
import type { Equal, Expect } from '@type-challenges/utils'

const promiseAllTest1 = PromiseAll([1, 2, 3] as const)
const promiseAllTest2 = PromiseAll([1, 2, Promise.resolve(3)] as const)
const promiseAllTest3 = PromiseAll([1, 2, Promise.resolve(3)])
const promiseAllTest4 = PromiseAll<Array<number | Promise<number>>>([1, 2, 3])
type s = Promise<[1, 2, 3]>;

type cases = [
  Expect<Equal<typeof promiseAllTest1, Promise<[1, 2, 3]>>>,
  Expect<Equal<typeof promiseAllTest2, Promise<[1, 2, number]>>>,
  Expect<Equal<typeof promiseAllTest3, Promise<[number, number, number]>>>,
  Expect<Equal<typeof promiseAllTest4, Promise<number[]>>>,
]