Verify-it NPM | npm.io

`verify-it`

Randomised test property/data generation for NodeJS.

This module provides:

Randomised property inputs for testing (delegating the actual testing to a global it or test function).
Global verify.it and verify.test functions (which are synonyms).
A global verify.describe function (delegating the actual testing to a global describe function).
A series of generator functions that can be used to generate properties.
Generators are simply functions that produce a value so custom generators are simple to create.

What it is not:

A property-based testing framework - each test scenario is only run once with the requested randomised inputs.

Usage

A global it or test function is required for verify-it to delegate testing to (it is used in preference to test). This could be provided by mocha, jest, jasmine or a similar testing framework.

A simple mocha example would be:

require('mocha')
const { Gen } = require('verify-it')

const myGenerator = () => `My custom generated value: ${Math.random()}`

describe('The verify-it library', () => {
  verify.it('should inject randomised properties',
    Gen.string, Gen.object, myGenerator,
    (someString, someObject, someCustomValue) => {
      // Write your tests here in the usual way using the supplied randomised values...
    }
  )

  verify.it('should allow testing of asynchronous callbacks if the test framework supports it', () => {
    Gen.string, Gen.object, myGenerator,
    (someString, someObject, someCustomValue, done) => {
      // Write some more tests here but call the done function when finished
      done()
    }
  )

  verify.describe('when verify.describe is used', Gen.object, (someObject) => {
    verify.it('allows the same generated value to be shared across multiple tests',
      Gen.object, (someOtherObject) => {
        // Write your tests here using both someObject and someOtherObject
      }
    )
  })
})

If your test framework has test.only or it.only and test.skip or test.skip then verify.it.only, verify.test.only, verify.it.skip, and verify.it.skip will also be available. Similarly, if describe.only or describe.skip exist, verify.describe.only and verify.describe.skip will be available.

Generators

Generators are simply functions that produce a value. Several built-in generators are supplied:

const { Gen } = require('verify-it')

Function	Produces	Notes
`Gen.word`	`string`	Produces an english word picked at random from a word list.
`Gen.string`	`string`	Produces a random string between 1 and 100 characters in length.
`Gen.stringWithLength(length)`	`string`	Produces a random string with a fixed length.
`Gen.stringNonNumeric`	`string`	Produces a random string that does not contain numeric characters between 1 and 100 characters in length.
`Gen.integer`	`number`	Produces a random integer in the inclusive range between `Number.MIN_SAFE_INTEGER` and `Number.MAX_SAFE_INTEGER`.
`Gen.integerBetween(min, max)`	`number`	Produces a random integer in the inclusive range between `min` and `max`.
`Gen.float`	`number`	Produces a random number in the inclusive range between `-1E10` and `1E10`
`Gen.floatBetween(min, max)`	`number`	Produces a random number in the inclusive range between `min` and `max`
`Gen.object`	`Object`	Produces an object with random word keys and randomised string values.
`Gen.objectWith(...keys)`	`Object`	Produces an object with the supplied keys and randomised string values.
`Gen.error`	`Error`	Produces an `Error` with a random message string.
`Gen.boolean`	`boolean`	Produces a random boolean value
`Gen.array(generator, length)`	`Array`	Produces an array with `length` elements (or between 1 and 100 elements if `length` is omitted) generated using `generator`. e.g. `Gen.array(Gen.string)` will produce an array of strings.
`Gen.distinct(generator, length)`	`Array`	Produces an array of length `length` with distinct values generated using `generator`. Equality is based on `===`. If distinct values cannot be generated after 10 generation attempts, an error will be thrown.
`Gen.pick(values)`	`any`	Picks a random element from the supplied `values` array.

Development

Install dependencies: yarn install.
Run all tests: yarn test.
Check dependencies for security vulnerabilities and licensing issues: yarn check-dependencies.