Mock Native API in your E2E test 2017/11/06 ElectronMeetup in Tokyo LT @joe_re

Who am I? twitter: @joe_re github: @joe­re community: Nishinippori.rb, GraphQL Tokyo Organizer

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Today, I talk about spectron E2E test in case of using 'Native API' in your spec.

Spectron

What is Spectron? E2E Testing tool for Electron appplication. You can call ElectronAPI in your spec via ChromeDriver and WebDriver.io.

Example const app = new spectron.Application({ path: 'path/to/your/app' }); describe('application launch', function () { this.timeout(10000); beforeEach(function () { return app.start(); }); afterEach(function () { return app.stop(); }); it('shows an initial window', function () { return app.client.getWindowCount().then(function (count) { assert.equal(count, 1); }); }); });

Strong Points You can access any DOM via Webdriver.io. You can call any Electron API in your spec. No need setup script.(use Chromium inside Electron) Support CI services.(Travis, AppVeyor, etc)

DEMO

Spectron is nice. But it can't access Native API. (latest v3.7.2) So it can't mock Menu, Dialog, etc modules... https://github.com/electron/spectron/issues/94

This is simple solution, but ugly... if (process.env.NODE_ENV === "production") { // production code here } else { // test code here }

I want to write a spec which doesn't affect production code.

I created two modules to resolve it. spectron­fake­menu https://github.com/joe­re/spectron­fake­menu spectron­fake­dialog https://github.com/joe­re/spectron­fake­dialog

Usage spectron­fake­menu const Application = require('spectron').Application; const fakeMenu = require('spectron-fake-menu'); const app = new Application({ path: electron, args: [ path.join(__dirname, '.') ] }); fakeMenu.apply(app); // apply fake menu await app.start(); fakeMenu.clickMenu('Config'); // 'Config' Menu click fakeMenu.clickMenu('File', 'CloseTab'); // File->CloseTab Menu click spectron­fake­dialog const Application = require('spectron').Application; const fakeDialog = require('spectron-fake-dialog'); const app = new Application({ path: electron, args: [ path.join(__dirname, '.') ] }); fakeDialog.apply(app); await app.start(); fakeDialog.mock([ { method: 'showOpenDialog', value: ['faked.txt'] } ])); // write your specs

How do they work? Electron provides '­­require' option same as Node.js. It can preload a module before run main script. These modules inject extra IPC and provide API which call or mock Native API inside your specs.

Rough image

Implementation(spectron­fake­dialog) const path = require('path'); let _app = null; function apply(app) { _app = app; _app.args.unshift(path.join(__dirname, 'preload.js')); _app.args.unshift('--require'); return _app; } function mock(options) { return _app.electron.ipcRenderer.sendSync('SPECTRON_FAKE_DIALOG/SEND', options); } module.exports = { apply, mock };

Implementation(spectron­fake­dialog) preload script const { dialog, ipcMain, BrowserWindow } = require('electron'); //... some logics for creating mocked function ... function fake(options) { options.forEach(v => { if (dialog[v.method]) { dialog[v.method] = mockFunction.bind(null, v.value); } else { throw new Error(`can't find ${v.method} on dialog module.`); } }); } ipcMain.on('SPECTRON_FAKE_DIALOG/SEND', (e, options) => { fake(options); e.returnValue = true; });

Please use they if you'd like.

Thank you for your attention!