test.js

const createValidation = (...validators) => (value) => {
  const errors = validators.reduce((errors, validator) => {
    const error = validator(value)
    if (error) {
      return errors.concat(error)
    }
    return errors
  }, [])
  return errors.length > 0 ? errors : null
}

const createValidator = (checkFn, errorMessage) => {
  return value => {
    if (!checkFn(value)) {
      return errorMessage
    }
  }
}

const hasEmail = value => /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/.test(value)

const hasNoEmpty = (value = '') => !!value.trim()

const hasAdult = (age) => age >= 18

module.exports = {
  createValidation,
  createValidator,
  hasEmail,
  hasNoEmpty,
  hasAdult,
}