mocha-wrap

Fluent pluggable interface for easily wrapping `describe` and `it` blocks in Mocha tests

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Jordan Harband

Jordan Harband

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Fluent pluggable interface for easily wrapping describe, context, and it blocks in Mocha tests.

Example

var wrap = require('mocha-wrap');
var expect = require('chai').expect;

var mockWindow = {
	location: {
		href: 'test/url'
	}
};
wrap().withGlobal('window', () => mockWindow).describe('mocked window', function () {
	it('is mocked', function () {
		expect(window).to.equal(mockWindow);
	});

	it('has the right URL', function () {
		expect(window.location.href).to.equal('test/url');
	});
});

var obj = { a: 1 };
wrap().withOverrides(() => obj, () => ({ a: 2, b: 3 })).describe('overridden object keys', function () {
	it('has "b"', function () {
		expect(obj.b).to.equal(3);
	});

	it('has overridden "a"', function () {
		expect(obj.a).to.equal(2);
	});
});

wrap().withOverride(() => obj, 'a', () => 4).skip().describe('this test is skipped', function () {
	it('also supports .only()!', function () {
		expect(true).to.equal(false); // skipped
	});
});

Plugins

A mocha-wrap plugin is a named function that returns a MochaWrapper instance or a descriptor object. - A plugin’s function name must begin with the string “with”. - Plugins can be globally registered, or .used ad-hoc. - .use requires a plugin function as its first argument; further arguments are passed through to the plugin. - .extend requires a non-empty description string, and a descriptor object which may contain a value that is a function, or an array of functions, whose keys correspond to any or all of the supported mocha methods. - Globally registered plugins, .use calls, and .extend calls can be chained, stored, and reused - each link in the chain creates a new instance of a MochaWrapper.

  • A descriptor object may contain any or all of these 5 keys:
  • a description string, for use in “describe” and/or “it” (this is required when returning an object)
  • beforeEach: a function, or array of functions, for use in a mocha beforeEach function
  • afterEach: a function, or array of functions, for use in a mocha afterEach function
  • before: a function, or array of functions, for use in a mocha before function
  • after: a function, or array of functions, for use in a mocha after function

The most common approach will be for a plugin function to return this.extend(description, descriptor).

A plugin function must have a name that starts with “with”, and will be invoked with a receiver (”this” value) of a MochaWrapper instance.

To register a plugin, call the register function on mocha-wrap with the plugin function. This should not be done in a reusable module.

module.exports = function withFoo(any, args, you, want) {
	return this.extend('with some foo stuff', {
		beforeEach: function () {
			// setup ran before each test
		},
		afterEach: [
			function () {
				// teardown ran after each test
			},
			function () {
				// more teardown
			}
		],
		before: function () {
			// setup ran once before all tests
		},
		after: function () {
			// teardown ran once after all tests
		}
	});
};

Usage

var wrap = require('mocha-wrap');
wrap.register(require('mocha-wrap-with-foo'));

wrap().withFoo().describe

skip/only

Although mocha has describe.skip, describe.only, context.skip, context.only, it.skip, and it.only, it is not possible to implement these in mocha-wrap without using ES5 property accessors. Since this project supports ES3, we decided to use .skip().describe etc rather than forfeit the ability to have skip/only.

Tests

Simply clone the repo, npm install, and run npm test

Jordan Harband

Jordan Harband

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