[![power-assert][power-assert-banner]][power-assert-url] Power Assert in JavaScript. Provides descriptive assertion messages through standard [assert](https://nodejs.org/api/assert.html) interface. No API is the best API. [![Build Status][travis-image]][travis-url] [![NPM package][npm-image]][npm-url] [![Bower package][bower-image]][bower-url] [![Dependency Status][depstat-image]][depstat-url] [![License][license-image]][license-url] DESCRIPTION --------------------------------------- What is `power-assert`? * is an implementation of "Power Assert" concept in JavaScript. * provides descriptive assertion messages through standard [assert](https://nodejs.org/api/assert.html) interface. * __No API is the best API__. With power-assert, __you don't need to learn many assertion library APIs__ (in most cases, all you need to remember is just an `assert(any_expression)` function) * __Stop memorizing tons of assertion APIs. Just create expressions that return a truthy value or not__ and power-assert will show it to you right on the screen as part of your failure message without you having to type in a message at all. * the core value of power-assert is absolute simplicity and stability. Especially, power-assert sticks to the simplest form of testing, `assert(any_expression)`. * see slides: ["power-assert, mechanism and philosophy"](https://www.slideshare.net/t_wada/power-assert-nodefest-2014) -- talk at NodeFest 2014. * __[NEW] Now you don't need `require('power-assert')` any more. Keep using `require('assert')`, and power-assert enhances them transparently.__ See slides: [From Library to Tool - power-assert as a General Purpose Assertion Enhancement Tool](https://speakerdeck.com/twada/from-library-to-tool-power-assert-as-a-general-purpose-assertion-enhancement-tool) * to gain power-assert output, __you need to transform your test code__ to produce power-assert output. * `power-assert - power = assert`. Without code transpilation, power-assert works just as normal `assert` does. * fully compatible with [assert](https://nodejs.org/api/assert.html). So you can stop using power-assert and back to assert easily. * has [online demo site](https://azu.github.io/power-assert-demo/). * works both on server side and browser side. * available via [npm](https://www.npmjs.com/package/power-assert) and [bower](https://bower.io/search/?q=power-assert). * supports sourcemaps so you can debug as usual. * provides [babel plugin](https://github.com/power-assert-js/babel-plugin-espower) and [babel preset](https://github.com/power-assert-js/babel-preset-power-assert). * provides [browserify transform](https://github.com/power-assert-js/espowerify). * provides [webpack loader](https://github.com/power-assert-js/webpack-espower-loader). * provides [grunt task](https://github.com/power-assert-js/grunt-espower) and [gulp plugin](https://github.com/power-assert-js/gulp-espower). * provides [command](https://github.com/power-assert-js/espower-cli). * provides [custom module loader](https://github.com/power-assert-js/espower-loader) and its [convenient config module](https://github.com/power-assert-js/intelli-espower-loader). * provides [Karma Adapter](https://github.com/power-assert-js/karma-power-assert) and [Karma Preprocessor](https://github.com/power-assert-js/karma-espower-preprocessor). * supports ES6+ through [babel plugin](https://github.com/power-assert-js/babel-plugin-espower). * supports [CoffeeScript](https://github.com/power-assert-js/espower-coffee). * supports [TypeScript](https://github.com/power-assert-js/espower-typescript). * has [TypeScript type definition](https://www.npmjs.com/package/@types/power-assert) * has code migration tool that transforms existing code from [chai](https://github.com/twada/chai-to-assert), [should.js](https://github.com/node-modules/should2assert) and [expect.js](https://github.com/twada/expect-js-to-assert) to assert. * [AVA](https://github.com/avajs/ava), the futuristic test runner, now [comes with power-assert builtin](https://github.com/avajs/ava#enhanced-assertion-messages) * has [Lab transformer](https://github.com/feugy/lab-espower-transformer) to enable power-assert on [Lab](https://github.com/hapijs/lab) * has [module loader](https://github.com/tracecomms/espower-ts-node) to get [ts-node](https://github.com/TypeStrong/ts-node) working together with power-assert * [Wallaby.js](https://wallabyjs.com/) supports power-assert via [Babel compiler/preprocessor](https://github.com/wallabyjs/public/issues/754#issuecomment-241624868) * pull-requests, issue reports and patches are always welcomed. `power-assert` provides descriptive assertion messages for your tests, like this. 1) Array #indexOf() should return index when the value is present: AssertionError: # path/to/test/mocha_node.js:10 assert(ary.indexOf(zero) === two) | | | | | | | | | 2 | -1 0 false [1,2,3] [number] two => 2 [number] ary.indexOf(zero) => -1 API --------------------------------------- power-assert enhances these assert functions by [espower](https://github.com/power-assert-js/espower). Produces descriptive message when assertion is failed. * [`assert(value, [message])`](https://nodejs.org/api/assert.html#assert_assert_value_message) * [`assert.ok(value, [message])`](https://nodejs.org/api/assert.html#assert_assert_ok_value_message) * [`assert.equal(actual, expected, [message])`](https://nodejs.org/api/assert.html#assert_assert_equal_actual_expected_message) * [`assert.notEqual(actual, expected, [message])`](https://nodejs.org/api/assert.html#assert_assert_notequal_actual_expected_message) * [`assert.strictEqual(actual, expected, [message])`](https://nodejs.org/api/assert.html#assert_assert_strictequal_actual_expected_message) * [`assert.notStrictEqual(actual, expected, [message])`](https://nodejs.org/api/assert.html#assert_assert_notstrictequal_actual_expected_message) * [`assert.deepEqual(actual, expected, [message])`](https://nodejs.org/api/assert.html#assert_assert_deepequal_actual_expected_message) * [`assert.notDeepEqual(actual, expected, [message])`](https://nodejs.org/api/assert.html#assert_assert_notdeepequal_actual_expected_message) * [`assert.deepStrictEqual(actual, expected, [message])`](https://nodejs.org/api/assert.html#assert_assert_deepstrictequal_actual_expected_message) * [`assert.notDeepStrictEqual(actual, expected, [message])`](https://nodejs.org/api/assert.html#assert_assert_notdeepstrictequal_actual_expected_message) power-assert is fully compatible with [assert](https://nodejs.org/api/assert.html). So functions below are also available though they are not enhanced (does not produce descriptive message). * [`assert.fail(actual, expected, message, operator)`](https://nodejs.org/api/assert.html#assert_assert_fail_actual_expected_message_operator_stackstartfunction) * [`assert.throws(block, [error], [message])`](https://nodejs.org/api/assert.html#assert_assert_throws_block_error_message) * [`assert.doesNotThrow(block, [message])`](https://nodejs.org/api/assert.html#assert_assert_doesnotthrow_block_error_message) * [`assert.ifError(value)`](https://nodejs.org/api/assert.html#assert_assert_iferror_value) Since version 1.5.0, power-assert supports ["strict mode"](https://nodejs.org/api/assert.html#assert_strict_mode) as well. power-assert provides an [API for customization](https://github.com/power-assert-js/power-assert#customization-api). * `assert.customize(options)` ### No API is the best API Though power-assert is fully compatible with standard [assert](https://nodejs.org/api/assert.html) interface, all you need to remember is just an `assert(any_expression)` function in most cases. The core value of power-assert is absolute simplicity and stability. Especially, power-assert sticks to the simplest form of testing, `assert(any_expression)`. assert(types[index].name === bob.name) | || | | | | | || | | | "bob" | || | | Person{name:"bob",age:5} | || | false | |11 "alice" | Person{name:"alice",age:3} ["string",98.6,true,false,null,undefined,#Array#,#Object#,NaN,Infinity,/^not/,#Person#] --- [string] bob.name +++ [string] types[index].name @@ -1,3 +1,5 @@ -bob +alice FAQ --------------------------------------- - [Support other assertion styles?](https://github.com/power-assert-js/power-assert/issues/22) - [Does this work with substack/tape?](https://github.com/power-assert-js/power-assert/issues/30) - [Are all dependencies required at runtime?](https://github.com/power-assert-js/power-assert/issues/24) - [Descriptive assertion message does not appear when writing tests in ES6 with Babel](https://github.com/power-assert-js/webpack-espower-loader/issues/4#issuecomment-139605343) - [Incomplete increment/decrement assertion messages?](https://github.com/power-assert-js/power-assert/issues/32) - [Cannot capture not invokable method error](https://github.com/power-assert-js/power-assert/issues/36) - What is the ['Critical dependencies' warning shown by webpack](https://github.com/power-assert-js/babel-plugin-espower/issues/14#issuecomment-197272436) and how to [suppress warnings](https://github.com/power-assert-js/babel-plugin-espower/issues/14#issuecomment-197909419)? - [Causes `TypeError: assert._capt is not a function`](https://github.com/power-assert-js/power-assert/issues/42) - [How to deal with `assert` calls in production](https://github.com/power-assert-js/power-assert/issues/43#issuecomment-208851919) - [Support JSX tags?](https://github.com/power-assert-js/power-assert/issues/34#issuecomment-269848058) - [Any tool to migrate `should/expect` code to `power-assert`?](https://github.com/power-assert-js/power-assert/issues/74) - [Conflicts with babel-plugin-istanbul?](https://github.com/power-assert-js/babel-preset-power-assert/issues/4) - [power-assert message does not appear in Node8](https://github.com/power-assert-js/power-assert/issues/85) INSTALL --------------------------------------- `npm install --save-dev power-assert ` or ``` bower install --save-dev power-assert npm install --save-dev ``` see [list of instrumentors](https://github.com/power-assert-js/power-assert#be-sure-to-transform-test-code) CHANGELOG --------------------------------------- See [CHANGELOG](https://github.com/power-assert-js/power-assert/blob/master/CHANGELOG.md) EXAMPLE --------------------------------------- See [HOW TO USE](https://github.com/power-assert-js/power-assert#how-to-use) section for more details. __Note:__ There is an [online demo site](https://azu.github.io/power-assert-demo/) available. ### Target test code (using Mocha in this example) ```javascript 'use strict'; const assert = require('assert'); describe('Array', function(){ let ary; beforeEach(() => { ary = [1,2,3]; }); describe('#indexOf()', () => { it('should return index when the value is present', () => { const zero = 0, two = 2; assert(ary.indexOf(zero) === two); }); it('should return -1 when the value is not present', () => { const minusOne = -1, two = 2; assert.ok(ary.indexOf(two) === minusOne, 'THIS IS AN ASSERTION MESSAGE'); }); }); }); describe('various types', () => { let types; class Person { constructor(name, age) { this.name = name; this.age = age; } } beforeEach(() => { types = [ 'string', 98.6, true, false, null, undefined, ['nested', 'array'], {object: true}, NaN, Infinity, /^not/, new Person('alice', 3) ]; }); it('demo', () => { const index = types.length -1, bob = new Person('bob', 5); assert(types[index].name === bob.name); }); }); ``` ### Be sure to transform test code To use power-assert, you need to transform your test code for power-assert output. Code transform is done by instrumentors below: - [espower-loader](https://github.com/power-assert-js/espower-loader) (with [intelli-espower-loader](https://github.com/power-assert-js/intelli-espower-loader)) - [babel-preset-power-assert](https://github.com/power-assert-js/babel-preset-power-assert) - [babel-plugin-espower](https://github.com/power-assert-js/babel-plugin-espower) - [espowerify](https://github.com/power-assert-js/espowerify) - [webpack-espower-loader](https://github.com/power-assert-js/webpack-espower-loader). - [espower-cli](https://github.com/power-assert-js/espower-cli) - [grunt-espower](https://github.com/power-assert-js/grunt-espower) - [gulp-espower](https://github.com/power-assert-js/gulp-espower) - [karma-espower-preprocessor](https://github.com/power-assert-js/karma-espower-preprocessor) - [espower-coffee](https://github.com/power-assert-js/espower-coffee) - [espower-typescript](https://github.com/power-assert-js/espower-typescript) - [espower-traceur](https://github.com/power-assert-js/espower-traceur) If you are using Node.js only, the easiest way is to use [intelli-espower-loader](https://github.com/power-assert-js/intelli-espower-loader). Steps are as follows. ### Setup `npm install --save-dev mocha power-assert intelli-espower-loader` ### Run Put tests into `test` directory then run. You will see the power-assert output appears. $ $(npm bin)/mocha --require intelli-espower-loader path/to/test/mocha_node.js Array #indexOf() 1) should return index when the value is present 2) should return -1 when the value is not present various types 3) demo 0 passing (43ms) 3 failing 1) Array #indexOf() should return index when the value is present: AssertionError: # test/example2.js:13 assert(ary.indexOf(zero) === two) | | | | | | | | | 2 | -1 0 false [1,2,3] [number] two => 2 [number] ary.indexOf(zero) => -1 + expected - actual -false +true at Context.it (test/example2.js:13:13) 2) Array #indexOf() should return -1 when the value is not present: AssertionError: THIS IS AN ASSERTION MESSAGE # test/example2.js:17 assert.ok(ary.indexOf(two) === minusOne, 'THIS IS AN ASSERTION MESSAGE') | | | | | | | | | -1 | 1 2 false [1,2,3] [number] minusOne => -1 [number] ary.indexOf(two) => 1 + expected - actual -false +true at Context.it (test/example2.js:17:20) 3) various types demo: AssertionError: # test/example2.js:43 assert(types[index].name === bob.name) | || | | | | | || | | | "bob" | || | | Person{name:"bob",age:5} | || | false | |11 "alice" | Person{name:"alice",age:3} ["string",98.6,true,false,null,undefined,#Array#,#Object#,NaN,Infinity,/^not/,#Person#] --- [string] bob.name +++ [string] types[index].name @@ -1,3 +1,5 @@ -bob +alice + expected - actual -false +true at Context.it (test/example2.js:43:9) SEED PROJECTS --------------------------------------- Some seed projects are available to help you start with power-assert. | module | env | tech stack | |:-------|:------------|:------------| | [power-assert-node-seed](https://github.com/azu/power-assert-node-seed) | Node.js | power-assert + [intelli-espower-loader](https://github.com/power-assert-js/intelli-espower-loader) | | [power-assert-testem-seed](https://github.com/azu/power-assert-testem-seed) | Browsers(by [testem](https://github.com/testem/testem)) | power-assert + [gulp-espower](https://github.com/power-assert-js/gulp-espower) + [testem](https://github.com/airportyh/testem). | | [power-assert-karma-seed](https://github.com/azu/power-assert-karma-seed) | Browsers(by [Karma](https://karma-runner.github.io/)) | power-assert + [espowerify](https://github.com/power-assert-js/espowerify) + [browserify](http://browserify.org/) + [Karma](https://karma-runner.github.io/). | HOW TO USE --------------------------------------- There are some ways to use power-assert. (If you want to see running examples, see [SEED PROJECTS](#seed-projects)) 1. `power-assert` + `Babel` + `babel-preset-power-assert`: The only way to enable power-assert if you are using [Babel6+](https://babeljs.io/). 2. `power-assert` + `espower-loader` or `intelli-espower-loader` : Simple and recommended (but only works under Node). 3. `power-assert` + `espower-coffee` or `espower-typescript`: Use power-assert with AltJS. Recommended but only works under Node. 4. `power-assert` + `browserify` + `espowerify`: if you are using [browserify](http://browserify.org/) but not with Babel. 5. `power-assert` + `webpack` + `webpack-espower-loader`: if you are using [webpack](https://webpack.github.io/) but not with Babel. 6. `power-assert` + `espower-cli` or `grunt-espower` or `gulp-espower` : Generate instrumented code so works anywhere. ### using `babel-preset-power-assert` or `babel-plugin-espower` If you are writing your code with Babel, you can instrument Power Assert feature with Babel and babel-preset-power-assert (or babel-plugin-espower). see [babel-plugin-espower README](https://github.com/power-assert-js/babel-plugin-espower) and [babel-preset-power-assert README](https://github.com/power-assert-js/babel-preset-power-assert) ### using `espower-loader` or `intelli-espower-loader` If you are writing Node.js app/module, you can instrument Power Assert feature without code generation by using `espower-loader`. see [espower-loader README](https://github.com/power-assert-js/espower-loader). FYI: You may be interested in [intelli-espower-loader](https://github.com/power-assert-js/intelli-espower-loader) to go one step further. With [intelli-espower-loader](https://github.com/power-assert-js/intelli-espower-loader), you don't need to create loader file (like `enable-power-assert.js`). Just define test directory in `package.json` wow! ### using `espower-typescript` If you are writing Node.js app/module in TypeScript, you can instrument Power Assert feature without code generation by using `espower-typescript`. see [espower-typescript README](https://github.com/power-assert-js/espower-typescript). ### using `espower-coffee` If you are writing Node.js app/module in CoffeeScript, you can instrument Power Assert feature without code generation by using `espower-coffee`. see [espower-coffee README](https://github.com/power-assert-js/espower-coffee). ### using `espowerify` If you are using [browserify](http://browserify.org/) but not with Babel, you can instrument Power Assert feature via `espowerify`. see [espowerify README](https://github.com/power-assert-js/espowerify). ### using `webpack-espower-loader` If you are using [webpack](https://webpack.github.io/) but not with Babel, you can instrument Power Assert feature via `webpack-espower-loader`. see [webpack-espower-loader README](https://github.com/power-assert-js/webpack-espower-loader). ### using `espower-cli` If you don't want to use grunt, gulp, browserify, and so on, you can use `power-assert` via bower, with generated code by `espower-cli` see [espower-cli README](https://github.com/power-assert-js/espower-cli). ### using `gulp-espower` On the browser side and you are not using [browserify](http://browserify.org/) but [bower](https://bower.io/) and [gulp](http://gulpjs.com/), you can use `power-assert` via bower, with generated code by `gulp-espower` see [gulp-espower README](https://github.com/power-assert-js/gulp-espower). ### using `grunt-espower` On the browser side and you are not using [browserify](http://browserify.org/) but [bower](https://bower.io/) and [Grunt](http://gruntjs.com/), you can use `power-assert` via bower, with generated code by `grunt-espower` see [grunt-espower README](https://github.com/power-assert-js/grunt-espower). CUSTOMIZATION API --------------------------------------- `power-assert` provides an API for customization. ### var assert = assert.customize(options) Through this API, you can customize power-assert by changing some options. ```javascript var assert = require('power-assert').customize({ output: { maxDepth: 2 } }); ``` ### options `options` has two top-level keys. `assertion` and `output`. #### options.assertion customization options for [empower](https://github.com/power-assert-js/empower) module. See [empower API documentation](https://github.com/power-assert-js/empower#api) for details. Note that some default values are different from `empower`'s (`modifyMessageOnRethrow: true` and `saveContextOnRethrow: true`). #### options.output customization options for [power-assert-formatter](https://github.com/power-assert-js/power-assert-formatter) module. See [power-assert-formatter API documentation](https://github.com/power-assert-js/power-assert-formatter#api) for details. #### default values customizable properties and their default values are as follows. ```javascript var assert = require('power-assert').customize({ assertion: { destructive: false, modifyMessageOnRethrow: true, saveContextOnRethrow: true, patterns: [ 'assert(value, [message])', 'assert.ok(value, [message])', 'assert.equal(actual, expected, [message])', 'assert.notEqual(actual, expected, [message])', 'assert.strictEqual(actual, expected, [message])', 'assert.notStrictEqual(actual, expected, [message])', 'assert.deepEqual(actual, expected, [message])', 'assert.notDeepEqual(actual, expected, [message])', 'assert.deepStrictEqual(actual, expected, [message])', 'assert.notDeepStrictEqual(actual, expected, [message])' ] }, output: { lineDiffThreshold: 5, maxDepth: 1, anonymous: 'Object', circular: '#@Circular#', lineSeparator: '\n', ambiguousEastAsianCharWidth: 2, widthOf: (Function to calculate width of string. Please see power-assert-formatter's documentation) stringify: (Function to stringify any target value. Please see power-assert-formatter's documentation) diff: (Function to create diff string between two strings. Please see power-assert-formatter's documentation) writerClass: (Constructor Function for output writer class. Please see power-assert-formatter's documentation) renderers: [ './built-in/file', './built-in/assertion', './built-in/diagram', './built-in/binary-expression' ] } }); ``` INTERNAL DESIGN --------------------------------------- `power-assert` family provides 1 main module, 4 core modules and many more instrumentors. Main (facade) module is, | module | description | |:-------|:------------| | [power-assert](https://github.com/power-assert-js/power-assert) | Standard `assert` function on top of `empower` and `power-assert-formatter` | core modules are, | module | description | |:-------|:------------| | [empower](https://github.com/power-assert-js/empower) | Power Assert feature enhancer for assert function/object. | | [power-assert-formatter](https://github.com/power-assert-js/power-assert-formatter) | Power Assert output formatter. | | [espower](https://github.com/power-assert-js/espower) | Power Assert feature instrumentor core based on the ECMAScript AST defined in [The ESTree Spec](https://github.com/estree/estree) (formerly known as [Mozilla SpiderMonkey Parser API](https://developer.mozilla.org/en-US/docs/Mozilla/Projects/SpiderMonkey/Parser_API)). | | [espower-source](https://github.com/power-assert-js/espower-source) | Power Assert instrumentor from source to source, with source-map. (Thin wrapper of `espower`). | and instrumentors are, | module | description | |:-------|:------------| | [espower-loader](https://github.com/power-assert-js/espower-loader) | Node module loader to apply `espower` on the fly. | | [intelli-espower-loader](https://github.com/power-assert-js/intelli-espower-loader) | configure `espower-loader` with ease. | | [babel-preset-power-assert](https://github.com/power-assert-js/babel-preset-power-assert) | [Babel](https://babeljs.io/) preset to instrument power-assert feature into target files. | | [babel-plugin-espower](https://github.com/power-assert-js/babel-plugin-espower) | [Babel](https://babeljs.io/) plugin to instrument power-assert feature into target files. | | [espowerify](https://github.com/power-assert-js/espowerify) | [Browserify](http://browserify.org/) transform to apply `espower` to target files. | | [webpack-espower-loader](https://github.com/power-assert-js/webpack-espower-loader) | Power Assert instrumentor module for [webpack](https://webpack.github.io/). | | [espower-cli](https://github.com/power-assert-js/espower-cli) | Command line tool for power-assert. | | [grunt-espower](https://github.com/power-assert-js/grunt-espower) | Grunt task to apply `espower` to target files. | | [gulp-espower](https://github.com/power-assert-js/gulp-espower) | Gulp plugin to apply `espower` to target files. | | [karma-espower-preprocessor](https://github.com/power-assert-js/karma-espower-preprocessor) | karma-preprocessor for power-assert. | | [espower-coffee](https://github.com/power-assert-js/espower-coffee) | power-assert instrumentor for CoffeeScript. | | [espower-typescript](https://github.com/power-assert-js/espower-typescript) | power-assert instrumentor for TypeScript. | | [espower-traceur](https://github.com/power-assert-js/espower-traceur) | power-assert instrumentor for ES6 using [Traceur Compiler](https://github.com/google/traceur-compiler/). | | [espower-babel](https://github.com/power-assert-js/espower-babel) | [DEPRECATED] power-assert instrumentor for ES6 using [Babel](https://babeljs.io/). | `power-assert` provides standard [assert](https://nodejs.org/api/assert.html) compatible function with Power Assert feature. (Best fit with [Mocha](https://mochajs.org/). If you use assert-like objects provided by various testing frameworks such as [QUnit](https://qunitjs.com/) or [nodeunit](https://github.com/caolan/nodeunit). Please use [empower](https://github.com/power-assert-js/empower) and [power-assert-formatter](https://github.com/power-assert-js/power-assert-formatter) modules directly). Internally, `power-assert` uses [empower](https://github.com/power-assert-js/empower) module to enhance power assert feature into the standard [assert](https://nodejs.org/api/assert.html) module, to run with the power assert feature added code by [espower](https://github.com/power-assert-js/espower) module, and prettify output using [power-assert-formatter](https://github.com/power-assert-js/power-assert-formatter). See [power-assert-demo](https://github.com/twada/power-assert-demo) project for power-assert Demo running with mocha. SUPPORTED FRAMEWORKS --------------------------------------- * [Mocha](https://mochajs.org/) * [AVA](https://github.com/sindresorhus/ava) ### FRAMEWORKS KNOWN TO WORK * [Jest](https://facebook.github.io/jest/) with Babel * [Karma](https://karma-runner.github.io/) with Mocha * [testem](https://github.com/testem/testem) with Mocha * [QUnit](https://qunitjs.com/) * [nodeunit](https://github.com/caolan/nodeunit) * [buster-assertions](https://docs.busterjs.org/en/latest/modules/buster-assertions/) * [Lab](https://github.com/hapijs/lab) * [Nightmare](http://www.nightmarejs.org/) * [Protractor](http://www.protractortest.org/) * [eater](https://github.com/yosuke-furukawa/eater) OUR SUPPORT POLICY --------------------------------------- For the Transpiler side, we support Node under maintenance. In other words, we stop supporting old Node version when [their maintenance ends](https://github.com/nodejs/LTS). For the Runtime side, we support [Node under maintenance](https://github.com/nodejs/LTS) and "modern enough" browsers such as Chrome, Firefox, Safari, Edge etc. Any other environments are not supported officially (means that we do not test against them on CI service). power-assert is known to work with old browsers, and trying to keep them working though. AUTHOR --------------------------------------- * [Takuto Wada](https://github.com/twada) CONTRIBUTORS --------------------------------------- * [azu (azu)](https://github.com/azu) * [vvakame (Masahiro Wakame)](https://github.com/vvakame) * [yosuke-furukawa (Yosuke Furukawa)](https://github.com/yosuke-furukawa) * [teppeis (Teppei Sato)](https://github.com/teppeis) * [zoncoen (Kenta Mori)](https://github.com/zoncoen) * [falsandtru (falsandtru)](https://github.com/falsandtru) * [jamestalmage (James Talmage)](https://github.com/jamestalmage) * [LeshaKoss (Lesha Koss)](https://github.com/LeshaKoss) * [watilde (Daijirō Wachi)](https://github.com/watilde) LICENSE --------------------------------------- Licensed under the [MIT](https://github.com/power-assert-js/power-assert/blob/master/MIT-LICENSE.txt) license. MORE OUTPUT EXAMPLES --------------------------------------- ### Target test code (using QUnit in this example) ```javascript var q = require('qunitjs'); (function () { var empower = require('empower'), formatter = require('power-assert-formatter'), qunitTap = require("qunit-tap"); empower(q.assert, formatter(), {destructive: true}); qunitTap(q, require('util').puts, {showSourceOnFailure: false}); q.config.autorun = false; })(); q.test('spike', function (assert) { assert.ok(true); var hoge = 'foo'; var fuga = 'bar'; assert.ok(hoge === fuga, 'comment'); var piyo = 3; assert.ok(fuga === piyo); var longString = 'very very loooooooooooooooooooooooooooooooooooooooooooooooooooong message'; var anotherLongString = 'yet another loooooooooooooooooooooooooooooooooooooooooooooooooooong message'; assert.ok(longString === anotherLongString); assert.ok(4 === piyo); assert.ok(4 !== 4); var falsyStr = ''; assert.ok(falsyStr); var falsyNum = 0; assert.ok(falsyNum); var ary1 = ['foo', 'bar']; var ary2 = ['aaa', 'bbb', 'ccc']; assert.ok(ary1.length === ary2.length); assert.deepEqual(ary1, ary2); var actual = 16; assert.ok(5 < actual && actual < 13); actual = 4; assert.ok(5 < actual && actual < 13); actual = 10; assert.ok(actual < 5 || 13 < actual); var propName = 'bar', foo = { bar: { baz: false } }; assert.ok(foo.bar.baz); assert.ok(foo['bar'].baz); assert.ok(foo[propName]['baz']); var truth = true; assert.ok(!truth); var func = function () { return false; }; assert.ok(func()); var obj = { age: function () { return 0; } }; assert.ok(obj.age()); var isFalsy = function (arg) { return !(arg); }; var positiveInt = 50; assert.ok(isFalsy(positiveInt)); var sum = function () { var result = 0; for (var i = 0; i < arguments.length; i += 1) { result += arguments[i]; } return result; }; var one = 1, two = 2, three = 3, seven = 7, ten = 10; assert.ok(sum(one, two, three) === seven); assert.ok(sum(sum(one, two), three) === sum(sum(two, three), seven)); assert.ok((three * (seven * ten)) === three); var math = { calc: { sum: function () { var result = 0; for (var i = 0; i < arguments.length; i += 1) { result += arguments[i]; } return result; } } }; assert.ok(math.calc.sum(one, two, three) === seven); }); q.load(); ``` ### `espower` code above then running under Node.js ``` # module: undefined # test: spike ok 1 - okay not ok 2 - comment # path/to/examples/qunit_node.js:17 # # assert.ok(hoge === fuga, 'comment') # | | | # | | "bar" # | false # "foo" # # --- [string] fuga # +++ [string] hoge # @@ -1,3 +1,3 @@ # -bar # +foo # # , test: spike not ok 3 - # path/to/examples/qunit_node.js:20 # # assert.ok(fuga === piyo) # | | | # | | 3 # | false # "bar" # # [number] piyo # => 3 # [string] fuga # => "bar" # , test: spike not ok 4 - # path/to/examples/qunit_node.js:24 # # assert.ok(longString === anotherLongString) # | | | # | | "yet another loooooooooooooooooooooooooooooooooooooooooooooooooooong message" # | false # "very very loooooooooooooooooooooooooooooooooooooooooooooooooooong message" # # --- [string] anotherLongString # +++ [string] longString # @@ -1,15 +1,13 @@ # -yet anoth # +very v # er # +y # loo # # , test: spike not ok 5 - # path/to/examples/qunit_node.js:26 # # assert.ok(4 === piyo) # | | # | 3 # false # # [number] piyo # => 3 # [number] 4 # => 4 # , test: spike not ok 6 - # path/to/examples/qunit_node.js:28 # # assert.ok(4 !== 4) # | # false # , test: spike not ok 7 - # path/to/examples/qunit_node.js:31 # # assert.ok(falsyStr) # | # "" # , test: spike not ok 8 - # path/to/examples/qunit_node.js:34 # # assert.ok(falsyNum) # | # 0 # , test: spike not ok 9 - # path/to/examples/qunit_node.js:38 # # assert.ok(ary1.length === ary2.length) # | | | | | # | | | | 3 # | | | ["aaa","bbb","ccc"] # | 2 false # ["foo","bar"] # # [number] ary2.length # => 3 # [number] ary1.length # => 2 # , test: spike not ok 10 - # path/to/examples/qunit_node.js:39 # # assert.deepEqual(ary1, ary2) # | | # | ["aaa","bbb","ccc"] # ["foo","bar"] # , expected: [ # "aaa", # "bbb", # "ccc" # ], got: [ # "foo", # "bar" # ], test: spike not ok 11 - # path/to/examples/qunit_node.js:42 # # assert.ok(5 < actual && actual < 13) # | | | | | # | | | 16 false # | 16 false # true # , test: spike not ok 12 - # path/to/examples/qunit_node.js:45 # # assert.ok(5 < actual && actual < 13) # | | | # | 4 false # false # , test: spike not ok 13 - # path/to/examples/qunit_node.js:48 # # assert.ok(actual < 5 || 13 < actual) # | | | | | # | | | | 10 # | | false false # 10 false # , test: spike not ok 14 - # path/to/examples/qunit_node.js:58 # # assert.ok(foo.bar.baz) # | | | # | | false # | Object{baz:false} # Object{bar:#Object#} # , test: spike not ok 15 - # path/to/examples/qunit_node.js:59 # # assert.ok(foo['bar'].baz) # | | | # | | false # | Object{baz:false} # Object{bar:#Object#} # , test: spike not ok 16 - # path/to/examples/qunit_node.js:60 # # assert.ok(foo[propName]['baz']) # | || | # | |"bar" false # | Object{baz:false} # Object{bar:#Object#} # , test: spike not ok 17 - # path/to/examples/qunit_node.js:64 # # assert.ok(!truth) # || # |true # false # , test: spike not ok 18 - # path/to/examples/qunit_node.js:68 # # assert.ok(func()) # | # false # , test: spike not ok 19 - # path/to/examples/qunit_node.js:76 # # assert.ok(obj.age()) # | | # | 0 # Object{age:#function#} # , test: spike not ok 20 - # path/to/examples/qunit_node.js:83 # # assert.ok(isFalsy(positiveInt)) # | | # false 50 # , test: spike not ok 21 - # path/to/examples/qunit_node.js:94 # # assert.ok(sum(one, two, three) === seven) # | | | | | | # | | | | | 7 # 6 1 2 3 false # # [number] seven # => 7 # [number] sum(one, two, three) # => 6 # , test: spike not ok 22 - # path/to/examples/qunit_node.js:95 # # assert.ok(sum(sum(one, two), three) === sum(sum(two, three), seven)) # | | | | | | | | | | | # | | | | | | 12 5 2 3 7 # 6 3 1 2 3 false # # [number] sum(sum(two, three), seven) # => 12 # [number] sum(sum(one, two), three) # => 6 # , test: spike not ok 23 - # path/to/examples/qunit_node.js:96 # # assert.ok(three * (seven * ten) === three) # | | | | | | | # | | | | | | 3 # | | | | 10 false # | | 7 70 # 3 210 # # [number] three # => 3 # [number] three * (seven * ten) # => 210 # , test: spike not ok 24 - # path/to/examples/qunit_node.js:110 # # assert.ok(math.calc.sum(one, two, three) === seven) # | | | | | | | | # | | | | | | | 7 # | | 6 1 2 3 false # | Object{sum:#function#} # Object{calc:#Object#} # # [number] seven # => 7 # [number] math.calc.sum(one, two, three) # => 6 # , test: spike 1..24 ``` Have fun! [power-assert-url]: https://github.com/power-assert-js/power-assert [power-assert-banner]: https://raw.githubusercontent.com/power-assert-js/power-assert-js-logo/master/banner/banner-official-fullcolor.png [npm-url]: https://www.npmjs.com/package/power-assert [npm-image]: https://badge.fury.io/js/power-assert.svg [bower-url]: https://badge.fury.io/bo/power-assert [bower-image]: https://badge.fury.io/bo/power-assert.svg [travis-url]: https://travis-ci.org/power-assert-js/power-assert [travis-image]: https://secure.travis-ci.org/power-assert-js/power-assert.svg?branch=master [depstat-url]: https://gemnasium.com/power-assert-js/power-assert [depstat-image]: https://gemnasium.com/power-assert-js/power-assert.svg [license-url]: https://github.com/power-assert-js/power-assert/blob/master/MIT-LICENSE.txt [license-image]: https://img.shields.io/badge/license-MIT-brightgreen.svg?style=flat

	Stars	Issues	Version	Updated	Created
ava	20,648	59	6.1.3	a month ago	10 years ago
chai	8,075	96	5.1.1	23 days ago	12 years ago
mocha	22,469	244	10.4.0	2 months ago	13 years ago
power-assert	2,795	43	1.6.1	6 years ago	11 years ago
qunit			2.21.0	3 days ago	13 years ago
should	1,904	11	13.2.3	6 years ago	13 years ago

ava vs chai vs mocha vs power-assert vs qunit vs should

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