o/src/__tests__/find.spec.ts

common object helper functions

import find from '../find'
import { OObject, FindCallback } from '../types'

describe('find', (): void => {
  test('should return the first key which matches the callback evaluation', (): void => {
    const obj = {
      a: 1,
      b: 2,
      c: 3
    }

    expect(find(obj, (k, v): boolean => k === 'a' && v === 1)).toBe('a')
    expect(find(obj, (k, v): boolean => k === 'b' && v === 2)).toBe('b')
    expect(find(obj, (k, v): boolean => k === 'c' && v === 3)).toBe('c')
  })

  test('should the key of a deep object when follow is true', (): void => {
    const obj = {
      a: 1,
      b: {
        c: 2,
        d: {
          e: 3
        }
      }
    }

    expect(find(obj, (k, v): boolean => k === 'b.c' && v === 2, {
      follow: true
    })).toBe('b.c')
    expect(find(obj, (k, v): boolean => k === 'b.d.e' && v === 3, {
      follow: true
    })).toBe('b.d.e')
  })

  test('if all callbacks evaluate to false return undefined', (): void => {
    expect(find({}, (): boolean => false)).toBe(undefined)
    expect(find({}, (): boolean => false, {
      follow: true
    })).toBe(undefined)
  })

  test('should throw TypeError for invalid arguments', (): void => {
    const invalidObj: unknown = 'testing'
    const invalidCallback: unknown = 'testing'
    const invalidFollow: unknown = 'testing'

    expect((): string | undefined => find(invalidObj as OObject, jest.fn()))
      .toThrow(new TypeError('Expected Object, got string testing'))
    expect((): string | undefined => find({}, invalidCallback as FindCallback))
      .toThrow(new TypeError('Expected Function, got string testing'))
    expect((): string | undefined => find({}, jest.fn(), {
      follow: invalidFollow as boolean
    }))
      .toThrow(new TypeError('Expected Boolean, got string testing'))
  })
})