Cut-out

Cut-out is a JavaScript testing utility for RequireJS that makes it easier to mock and test your AMD modules. Cut-out's API is meant to be intuitive by mimicking RequireJS's API for configuration and module loading.

Cut-out is unopinionated regarding which test runner or mocking library you use, and should be compatible with all major test runners and mocking libraries out there. The documentation and examples for cutout use mocha and testdouble.js, but you should be able to extrapolate to your framework of choice.

Installation

To get started with cut-out, you can simply install it with npm:

npm i --save-dev cut-out

Usage

Cut-out matches RequireJS's API for configuration and module loading and can be used as a drop-in replacement.

To configure cut-out, simply call cutout.config with a configuration object, i.e.

cutout.config({
  baseUrl: './src',
  paths: {
    '_': 'lib/lodash'
  }
});

To load a module, call cutout with an array of modules and a callback function, i.e.

cutout(['some/module'], function (module) {
  // Work with example module
});

Cut-out adds two new methods to RequireJS's API: mock and reset: mock is used to replace a module with a mocked version while reset clears all existing mocks.

To mock a dependency, simply call cutout.mock with a dictionary of modules to their mocks, i.e.

const dependencyMock;

cutout.mock({
  'some/dependency': dependencyMock
});

To clear all existing mocks and return cut-out to an unmocked state, call cutout.reset with no arguments, i.e.

cutout.reset();

Example

const cutout = require('cut-out');
const expect = require('expect');
const td = require('testdouble');

describe('Module', function () {
  let dependency;
  let subject;

  before(function () {
    dependency = td.function();
    
    cutout.mock({
      'some/dependency': dependency
    });
  });
  
  beforEach(function (done) {
    cutout(['some/module'], function (module) {
      subject = module;
      done();
    });
  });
  
  afterEach(function () {
    td.reset();
  });
  
  after(function () {
    cutout.reset();
  });
  
  it('should test the module', function () {
    td.when(dependency()).thenReturn(true);
    
    expect(subject).toBe(true);
  });
});