import { expect } from 'chai'
import u from '../lib'

describe('u.if', () => {
  it('does not update if the predicate is false', () => {
    const object = { a: 0 }
    let result = u.if(false, { b: 1 }, object)
    expect(result).to.eql(object)

    result = u({ x: u.if(false, 1) }, {})
    expect(result).to.eql({})
  })

  it('does update if the predicate is true', () => {
    const object = { a: 0 }
    const result = u.if(true, { b: 1 }, object)
    expect(result).to.eql({ a: 0, b: 1 })
  })

  it('will use the result of a function passed as a predicate', () => {
    const object = { a: 0 }
    const aIsThree = x => x.a === 3
    const result = u.if(aIsThree, { b: 1 }, object)

    expect(result).to.eql({ a: 0 })
  })

  it('can be partially applied', () => {
    const object = { a: 2 }
    const isEven = x => x % 2 === 0
    const inc = x => x + 1

    const result = u(
      {
        a: u.if(isEven, inc),
      },
      object
    )

    expect(result).to.eql({ a: 3 })
  })

  it('freezes the result', () => {
    expect(Object.isFrozen(u.if(true, {}, {}))).to.be.true
    expect(Object.isFrozen(u.if(false, {}, {}))).to.be.true
  })
})