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Mocha (JavaScript framework)

JavaScript test framework running on Node.js

Wikipedia contributorsAdapted for Fathomly · View authors
1 min read
Source updated March 31, 2025

Mocha is a JavaScript test framework for Node.js programs, featuring browser support, asynchronous testing, test coverage reports, and use of any assertion library.

01Assertion libraries

Mocha can be used with most JavaScript assertion libraries, including:

  • should.js
  • express.js
  • chai
  • better-assert
  • unexpected

02Usage and examples

$ npm install -g mocha $ mkdir test $ $EDITOR test/test.js # or open with your favorite editor var assert = require("assert") describe('Foo', function(){ describe('#getBar(value)', function() { it('should return 100 when value is negative') // placeholder it('should return 0 when value is positive', function() { assert.equal(0, Foo.getBar(10)); }) }) }) $ mocha . 1 test complete (1ms)


For asynchronous testing, invoke the callback, and Mocha will wait for completion.

describe('Foo', function(){ describe('#bar()', function() { it('should work without error', function(done) { var foo = new Foo(128); foo.bar(done); }) }) })
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Sources and credits

This article is adapted from the Wikipedia article “Mocha (JavaScript framework)”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.

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