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

type A1 = StartsWith<'abc', 'ac'>;
type B1 = false;
type C1 = Expect<Equal<A1, B1>>;

type A2 = StartsWith<'abc', 'ab'>;
type B2 = true;
type C2 = Expect<Equal<A2, B2>>;

type A3 = StartsWith<'abc', 'abc'>;
type B3 = true;
type C3 = Expect<Equal<A3, B3>>;

type A4 = StartsWith<'abc', 'abcd'>;
type B4 = false;
type C4 = Expect<Equal<A4, B4>>;

type A5 = StartsWith<'abc', ''>;
type B5 = true;
type C5 = Expect<Equal<A5, B5>>;

type A6 = StartsWith<'abc', ' '>;
type B6 = false;
type C6 = Expect<Equal<A6, B6>>;

type A7 = StartsWith<'', ''>;
type B7 = true;
type C7 = Expect<Equal<A7, B7>>;

// ============= Your Code Here =============
type StartsWith<
  T extends string,
  U extends string
> =
  T extends `${U}${string}`
  ? true
  : false;

// ================== NOPE ==================
// show how to debug this by replacing false with 1 and 2
type StartsWith<
  T extends string,
  U extends string
> = 
  T extends `${infer L}${U}${infer R}`
  ? L extends ''
    ? true
    : false
  : false;