text: // maybe.test
  
  /* eslint-env jest */
  
  import {
    maybe
  } from './maybe.js'
  
  describe('test .maybe() method:', () => {
    const plus5 = (x) => x + 5
    const minus2 = (x) => x - 2
    const isNumber = (x) => Number(x) === x
    const toString = (x) => 'The value is ' + String(x)
    const getDefault = () => 'This is default value'
  
    test('  check if .maybe() works correctly', () => {
      const x1 = maybe(5)
        .if(isNumber)
        .map(plus5)
        .map(minus2)
        .map(toString)
        .else(getDefault)
        .value()
      expect(x1).toEqual('The value is 8')
  
      const x2 = maybe('nothing')
        .if(isNumber)
        .map(plus5)
        .map(minus2)
        .map(toString)
        .else(getDefault)
        .value()
      expect(x2).toEqual('This is default value')
    })
  })
  