https://github.com/erikras/expect-predicate

An extension for expect that lets you test values against arbitrary predicates
https://github.com/erikras/expect-predicate

Last synced: about 1 month ago
JSON representation

An extension for expect that lets you test values against arbitrary predicates

• Host: GitHub
• URL: https://github.com/erikras/expect-predicate
• Owner: erikras
• License: mit
• Created: 2016-04-29T08:58:54.000Z (over 8 years ago)
• Default Branch: master
• Last Pushed: 2016-04-29T09:12:39.000Z (over 8 years ago)
• Last Synced: 2024-09-21T10:27:18.160Z (about 2 months ago)
• Language: JavaScript
• Size: 4.88 KB
• Stars: 6
• Watchers: 3
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
# expect-predicate

---

[![NPM Version](https://img.shields.io/npm/v/expect-predicate.svg?style=flat-square)](https://www.npmjs.com/package/expect-predicate) 

[![NPM Downloads](https://img.shields.io/npm/dm/expect-predicate.svg?style=flat-square)](https://www.npmjs.com/package/expect-predicate)

[![Build Status](https://img.shields.io/travis/erikras/expect-predicate/master.svg?style=flat-square)](https://travis-ci.org/erikras/expect-predicate)

[![codecov.io](https://codecov.io/github/erikras/expect-predicate/coverage.svg?branch=master)](https://codecov.io/github/erikras/expect-predicate?branch=master)

[expect-predicate](https://github.com/erikras/expect-predicate) is an extension for

[expect](https://github.com/mjackson/expect) that lets you test values against arbitrary

predicates.

**A value "passes" a predicate if the predicate returns a truthy value.**

---

## Installation

Using [npm](https://www.npmjs.org/):

```bash

  $ npm install --save-dev expect expect-predicate

```

Then, use as you would anything else:

```js

// using ES6 modules

import expect from 'expect'

import expectPredicate from 'expect-predicate'

expect.extend(expectPredicate)

// using CommonJS modules

var expect = require('expect')

var expectPredicate = require('expect-predicate')

expect.extend(expectPredicate)

```

## Assertions

### toPass

> `expect(value).toPass(predicate, [message])`

Asserts the given value passes the given predicate. If you provide a message, it will be used 

when reporting the failure.

```js

expect(age).toPass(n => n >= 18)                // check age is 18 or older

expect(userList).toPass(array => array.length)  // check that userList is not empty

```

### toNotPass

> `expect(value).toNotPass(predicate, [message])`

Asserts the given value does NOT pass the given predicate. If you provide a message, it will be 

used when reporting the failure.

```js

expect(age).toNotPass(n => n < 18)                 // check age is not under 18

expect(userList).toNotPass(array => array.length)  // check that userList is empty

```