17973-medium-deepmutable.ts

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

interface Test1 {
  readonly title: string
  readonly description: string
  readonly completed: boolean
  readonly meta: {
    readonly author: string
  }
}
type Test2 = {
  readonly a: () => 1
  readonly b: string
  readonly c: {
    readonly d: boolean
    readonly e: {
      readonly g: {
        readonly h: {
          readonly i: true
          readonly j: 's'
        }
        readonly k: 'hello'
      }
      readonly l: readonly [
        'hi',
        {
          readonly m: readonly ['hey']
        }
      ]
    }
  }
}
interface DeepMutableTest1 {
  title: string
  description: string
  completed: boolean
  meta: {
    author: string
  }
}

type DeepMutableTest2 = {
  a: () => 1
  b: string
  c: {
    d: boolean
    e: {
      g: {
        h: {
          i: true
          j: 's'
        }
        k: 'hello'
      }
      l: [
        'hi',
        {
          m: ['hey']
        }
      ]
    }
  }
}

type cases = [Expect<Equal<DeepMutable<Test1>, DeepMutableTest1>>, Expect<Equal<DeepMutable<Test2>, DeepMutableTest2>>]

type errors = [
  // @ts-expect-error
  DeepMutable<'string'>,
  // @ts-expect-error
  DeepMutable<0>
]

// ============= Your Code Here =============
type DeepMutable<T extends Record<PropertyKey, any>> = T extends (...args: any[]) => any
  ? T
  : {
      -readonly [k in keyof T]: DeepMutable<T[k]>
    }