chance-generators

chance-generators

This module is thin wrapper around the excellent chance library for doing composable generators.

Installation

npm install --save chance-generators

Usage

var g = require('./lib/chance-generators')(42)
var emails = g.email({ domain: g.pick(['example.com', 'mail.me']) })
expect(emails(), 'to equal', '[e-mail]')
expect(emails(), 'to equal', '[e-mail]')
expect(emails(), 'to equal', '[e-mail]')

When you call any of the functions documented on www.chancejs.com with one of more arguments a new generator function is returned instead of just generating the result:

var positiveIntegers = g.integer({ min: 0 })
expect(positiveIntegers, 'to be a function')
expect(positiveIntegers(), 'to be a number')

If you call a generator without any arguments it will produce a new value.

expect(g.integer(), 'to be a number')

Any generators passed as parameters to other generators will be called to produce a random value:

var g = require('./lib/chance-generators')(42)
var smallStrings = g.string({ length: g.integer({ min: 3, max: 9 }) })
expect(smallStrings(), 'to equal', '(n25S')
expect(smallStrings(), 'to equal', 'GlheH#y')
expect(smallStrings(), 'to equal', '0Wbe)19')

The only exception to this rule is the n and unique functions, they don't dereference the generator given as the first argument:

var g = require('./lib/chance-generators')(42)
var stringArrays = g.n(g.string, g.integer({ min: 0, max: 10 }))

expect(stringArrays(), 'to equal', [
  '(n25SSlGlheH#ySk0', 'be)19*pan]nTwTM', 'FbvMT', 'kdv[BrHg6To'
])

expect(stringArrays(), 'to equal', [
  '[RId@SYmHea(*', 'P7CwbhrYrGYjTK9cm^Ct', 'X3xFMpO', 'nc)!5H*D%&S1&y'
])

expect(stringArrays(), 'to equal', [])

Additional generators

identity

Always generates the given value.

var g = require('./lib/chance-generators')(42)

expect(g.identity(42), 'to equal', 42)

shape

Generates values of the given shape, if the structure contains generators they will be unwrapped.

expect(chance.shape({
  constant: 42,
  point: {
    x: chance.integer,
    y: chance.integer
  }
}), 'when called', 'to satisfy', {
  constant: 42,
  point: {
    x: expect.it('to be a number'),
    y: expect.it('to be a number')
  }
})

MIT License

Copyright (c) 2016 Sune Simonsen [e-mail]

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.