00018-easy-tuple-length.ts

// ============= Test Cases =============
import type { Equal, Expect } from "./test-utils";

const tesla = ["tesla", "model 3", "model X", "model Y"] as const;
const spaceX = [
    "FALCON 9",
    "FALCON HEAVY",
    "DRAGON",
    "STARSHIP",
    "HUMAN SPACEFLIGHT",
] as const;

type cases = [
    Expect<Equal<Length<typeof tesla>, 4>>,
    Expect<Equal<Length<typeof spaceX>, 5>>,
    // @ts-expect-error
    Length<5>,
    // @ts-expect-error
    Length<"hello world">
];

// ============= Your Code Here =============
type Length<T extends readonly unknown[]> = T["length"];