import { one, partitionBy } from '../Set'

describe('Set', () => {
  describe('one', () => {
    it('should select one from a set', () => {
      const s = new Set([1, 2, 3])
      expect(one(s)).toBeSome()
    })

    it('should give None if set is empty', () => {
      const s = new Set()
      expect(one(s)).toBeNone()
    })
  })

  describe('partitionBy', () => {
    it('should give an empty array for an empty set', () => {
      const s = new Set<{ key: unknown }>()
      expect(partitionBy('key')(s)).toEqual([])
    })

    it('should partition a set of objects by some property', () => {
      const s = new Set([
        { key: 'foo', value: 1 },
        { key: 'bar', value: 3 },
        { key: 'foo', value: 2 },
        { key: 'baz', value: 7 },
        { key: 'bar', value: 2 },
      ])
      expect(partitionBy('key')(s)).toEqual([
        new Set([
          { key: 'foo', value: 1 },
          { key: 'foo', value: 2 },
        ]),
        new Set([
          { key: 'bar', value: 3 },
          { key: 'bar', value: 2 },
        ]),
        new Set([{ key: 'baz', value: 7 }]),
      ])
    })
  })
})