selectKeys.test.ts

import { expectType } from 'ts-expect'

import { D, pipe } from '../..'

const obj = { x: 123, y: 'abc', z: false }

const rec: Record<string, number> = { a: 1, b: 2, c: 3 }

describe('selectKeys', () => {
  it('provides correct types', () => {
    const keys = ['x', 'y'] as const

    expectType<Pick<typeof obj, 'x' | 'y'>>(D.selectKeys(obj, ['x', 'y']))
    expectType<typeof rec>(D.selectKeys(rec, ['a', 'b']))
    expectType<typeof rec>(D.selectKeys(rec, ['y', 'z']))
    expectType<typeof rec>(D.selectKeys(rec, keys))
  })

  it('selects the right keys', () => {
    expect(D.selectKeys(obj, ['x', 'y'])).toEqual({ x: 123, y: 'abc' })
    expect(D.selectKeys(rec, ['a', 'b'])).toEqual({ a: 1, b: 2 })
    expect(D.selectKeys(rec, ['y', 'z'])).toEqual({})
  })

  it('*', () => {
    expect(
      D.selectKeys({ name: 'Joe', location: 'Warsaw', age: 42 }, [
        'name',
        'age',
      ]),
    ).toEqual({ name: 'Joe', age: 42 })

    const obj: Record<string, string> = { name: 'Joe', location: 'Warsaw' }
    expect(
      // ⬇️ const obj: Record<string, string> = { name: 'Joe', location: 'Warsaw' }
      D.selectKeys(obj, ['name', 'age']),
    ).toEqual({ name: 'Joe' })
  })
})

describe('selectKeys (pipe)', () => {
  it('provides correct types', () => {
    expectType<Pick<typeof obj, 'x' | 'y'>>(pipe(obj, D.selectKeys(['x', 'y'])))
    expectType<typeof rec>(pipe(rec, D.selectKeys(['a', 'b'])))
    expectType<typeof rec>(pipe(rec, D.selectKeys(['y', 'z'])))
  })

  it('selects the right keys', () => {
    expect(pipe(obj, D.selectKeys(['x', 'y']))).toEqual({ x: 123, y: 'abc' })
    expect(pipe(rec, D.selectKeys(['a', 'b']))).toEqual({ a: 1, b: 2 })
    expect(pipe(rec, D.selectKeys(['y', 'z']))).toEqual({})
  })

  it('*', () => {
    expect(
      pipe(
        { name: 'Joe', location: 'Warsaw', age: 42 },
        D.selectKeys(['name', 'age']),
      ),
    ).toEqual({ name: 'Joe', age: 42 })

    const obj: Record<string, string> = { name: 'Joe', location: 'Warsaw' }
    expect(
      // ⬇️ const obj: Record<string, string> = { name: 'Joe', location: 'Warsaw' }
      pipe(obj, D.selectKeys(['name', 'age'])),
    ).toEqual({ name: 'Joe' })
  })
})