Promise mocking library to make Promises resolve synchronously
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Latest commit 62ac278 Feb 27, 2018

README.md

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Promise mocking library to make Promises resolve synchronously

Why

  • Tests are faster
  • Don't need done() function
  • Stack traces are preserved / Easier debugging
  • Can be easier to write tests (depends)

Don't Promises need to be async or else my code will break?

Nope

Use with Node and Webpack/Browserify

npm install promise-mock

Simple use with Mocha or Jasmine

Get the result of a Promise PromiseMock.getResult

import PromiseMock from 'promise-mock';

describe('testing', function() {
    beforeEach(function() {
        PromiseMock.install()
    });
    afterEach(function() {
        PromiseMock.uninstall();
    });
    it('Sync Promise test', function() {
        var result = PromiseMock.getResult(Promise.resolve('hello')));
        expect(result).toBe('hello');
    });
    
});

Handle errors synchronously

import PromiseMock from 'promise-mock';

describe('testing', function() {
    beforeEach(function() {
        PromiseMock.install()
    });
    afterEach(function() {
        PromiseMock.uninstall();
    });
    it('Sync Promise test', function() {
        expect(function() {
            PromiseMock.getResult(Promise.reject(new Error('An error')));
        }).toThrow(new Error('An Error'));
    });
});

Execute a single async callback

import PromiseMock from 'promise-mock';

describe('testing', function() {
    beforeEach(function() {
        PromiseMock.install()
    });
    afterEach(function() {
        PromiseMock.uninstall();
    });
    it('Sync Promise test', function() {
        var result;
        Promise.resolve('hello').then(function(data) {
            result = data;
        });
        Promise.run();
        expect(result).toBe('hello');
    });
    
});

Resolve all pending Promises

import PromiseMock from 'promise-mock';

describe('testing', function() {
    beforeEach(function() {
        PromiseMock.install()
    });
    afterEach(function() {
        PromiseMock.uninstall();
    });
    it('Sync Promise test', function() {
        var result1, result2, result3;
        Promise.resolve('hello1').then(function(data) {
            result1 = data;
            return 'hello2';
        }).then(function(data) {
            result2 = data;
            return 'hello3';
        }).then(function(data) {
            result3 = data;
        });;
        Promise.runAll();
        expect(result1).toBe('hello1');
        expect(result2).toBe('hello2');
        expect(result3).toBe('hello3');
    });
    
});

By default Promise.runAll() will throw an Error if there are no pending Promises. If you don't want an error, you can use Promise.runAll(false)

For commonjs/require webpack and rollup

Since the move to ES6 modules. You need to add .default

const PromiseMock = require('promise-mock').default;

Testing

npm install
npm test

License

MIT