electron/spec/guest-window-manager-spec.ts

import { BrowserWindow, screen } from 'electron';
import { expect, assert } from 'chai';
import { HexColors, ScreenCapture } from './lib/screen-helpers';
import { ifit, listen } from './lib/spec-helpers';
import { closeAllWindows } from './lib/window-helpers';
import { once } from 'node:events';
import { setTimeout as setTimeoutAsync } from 'node:timers/promises';
import * as http from 'node:http';

describe('webContents.setWindowOpenHandler', () => {
  describe('native window', () => {
    let browserWindow: BrowserWindow;
    beforeEach(async () => {
      browserWindow = new BrowserWindow({ show: false });
      await browserWindow.loadURL('about:blank');
    });

    afterEach(closeAllWindows);

    it('does not fire window creation events if the handler callback throws an error', (done) => {
      const error = new Error('oh no');
      const listeners = process.listeners('uncaughtException');
      process.removeAllListeners('uncaughtException');
      process.on('uncaughtException', (thrown) => {
        try {
          expect(thrown).to.equal(error);
          done();
        } catch (e) {
          done(e);
        } finally {
          process.removeAllListeners('uncaughtException');
          for (const listener of listeners) {
            process.on('uncaughtException', listener);
          }
        }
      });

      browserWindow.webContents.on('did-create-window', () => {
        assert.fail('did-create-window should not be called with an overridden window.open');
      });

      browserWindow.webContents.executeJavaScript("window.open('about:blank', '', 'show=no') && true");

      browserWindow.webContents.setWindowOpenHandler(() => {
        throw error;
      });
    });

    it('does not fire window creation events if the handler callback returns a bad result', async () => {
      const bad = new Promise((resolve) => {
        browserWindow.webContents.setWindowOpenHandler(() => {
          setTimeout(resolve);
          return [1, 2, 3] as any;
        });
      });

      browserWindow.webContents.on('did-create-window', () => {
        assert.fail('did-create-window should not be called with an overridden window.open');
      });

      browserWindow.webContents.executeJavaScript("window.open('about:blank', '', 'show=no') && true");

      await bad;
    });

    it('does not fire window creation events if an override returns action: deny', async () => {
      const denied = new Promise((resolve) => {
        browserWindow.webContents.setWindowOpenHandler(() => {
          setTimeout(resolve);
          return { action: 'deny' };
        });
      });

      browserWindow.webContents.on('did-create-window', () => {
        assert.fail('did-create-window should not be called with an overridden window.open');
      });

      browserWindow.webContents.executeJavaScript("window.open('about:blank', '', 'show=no') && true");

      await denied;
    });

    it('is called when clicking on a target=_blank link', async () => {
      const denied = new Promise((resolve) => {
        browserWindow.webContents.setWindowOpenHandler(() => {
          setTimeout(resolve);
          return { action: 'deny' };
        });
      });

      browserWindow.webContents.on('did-create-window', () => {
        assert.fail('did-create-window should not be called with an overridden window.open');
      });

      await browserWindow.webContents.loadURL('data:text/html,<a target="_blank" href="http://example.com" style="display: block; width: 100%; height: 100%; position: fixed; left: 0; top: 0;">link</a>');
      browserWindow.webContents.sendInputEvent({ type: 'mouseDown', x: 10, y: 10, button: 'left', clickCount: 1 });
      browserWindow.webContents.sendInputEvent({ type: 'mouseUp', x: 10, y: 10, button: 'left', clickCount: 1 });

      await denied;
    });

    it('is called when shift-clicking on a link', async () => {
      const denied = new Promise((resolve) => {
        browserWindow.webContents.setWindowOpenHandler(() => {
          setTimeout(resolve);
          return { action: 'deny' };
        });
      });

      browserWindow.webContents.on('did-create-window', () => {
        assert.fail('did-create-window should not be called with an overridden window.open');
      });

      await browserWindow.webContents.loadURL('data:text/html,<a href="http://example.com" style="display: block; width: 100%; height: 100%; position: fixed; left: 0; top: 0;">link</a>');
      browserWindow.webContents.sendInputEvent({ type: 'mouseDown', x: 10, y: 10, button: 'left', clickCount: 1, modifiers: ['shift'] });
      browserWindow.webContents.sendInputEvent({ type: 'mouseUp', x: 10, y: 10, button: 'left', clickCount: 1, modifiers: ['shift'] });

      await denied;
    });

    it('fires handler with correct params', async () => {
      const testFrameName = 'test-frame-name';
      const testFeatures = 'top=10&left=10&something-unknown&show=no';
      const testUrl = 'app://does-not-exist/';
      const details = await new Promise<Electron.HandlerDetails>(resolve => {
        browserWindow.webContents.setWindowOpenHandler((details) => {
          setTimeout(() => resolve(details));
          return { action: 'deny' };
        });

        browserWindow.webContents.executeJavaScript(`window.open('${testUrl}', '${testFrameName}', '${testFeatures}') && true`);
      });
      const { url, frameName, features, disposition, referrer } = details;
      expect(url).to.equal(testUrl);
      expect(frameName).to.equal(testFrameName);
      expect(features).to.equal(testFeatures);
      expect(disposition).to.equal('new-window');
      expect(referrer).to.deep.equal({
        policy: 'strict-origin-when-cross-origin',
        url: ''
      });
    });

    it('includes post body', async () => {
      const details = await new Promise<Electron.HandlerDetails>(resolve => {
        browserWindow.webContents.setWindowOpenHandler((details) => {
          setTimeout(() => resolve(details));
          return { action: 'deny' };
        });

        browserWindow.webContents.loadURL(`data:text/html,${encodeURIComponent(`
          <form action="http://example.com" target="_blank" method="POST" id="form">
            <input name="key" value="value"></input>
          </form>
          <script>form.submit()</script>
        `)}`);
      });
      const { url, frameName, features, disposition, referrer, postBody } = details;
      expect(url).to.equal('http://example.com/');
      expect(frameName).to.equal('');
      expect(features).to.deep.equal('');
      expect(disposition).to.equal('foreground-tab');
      expect(referrer).to.deep.equal({
        policy: 'strict-origin-when-cross-origin',
        url: ''
      });
      expect(postBody).to.deep.equal({
        contentType: 'application/x-www-form-urlencoded',
        data: [{
          type: 'rawData',
          bytes: Buffer.from('key=value')
        }]
      });
    });

    it('does fire window creation events if an override returns action: allow', async () => {
      browserWindow.webContents.setWindowOpenHandler(() => ({ action: 'allow' }));

      setImmediate(() => {
        browserWindow.webContents.executeJavaScript("window.open('about:blank', '', 'show=no') && true");
      });

      await once(browserWindow.webContents, 'did-create-window');
    });

    it('can change webPreferences of child windows', async () => {
      browserWindow.webContents.setWindowOpenHandler(() => ({ action: 'allow', overrideBrowserWindowOptions: { webPreferences: { defaultFontSize: 30 } } }));

      const didCreateWindow = once(browserWindow.webContents, 'did-create-window') as Promise<[BrowserWindow, Electron.DidCreateWindowDetails]>;
      browserWindow.webContents.executeJavaScript("window.open('about:blank', '', 'show=no') && true");
      const [childWindow] = await didCreateWindow;

      await childWindow.webContents.executeJavaScript("document.write('hello')");
      const size = await childWindow.webContents.executeJavaScript("getComputedStyle(document.querySelector('body')).fontSize");
      expect(size).to.equal('30px');
    });

    it('does not hang parent window when denying window.open', async () => {
      browserWindow.webContents.setWindowOpenHandler(() => ({ action: 'deny' }));
      browserWindow.webContents.executeJavaScript("window.open('https://127.0.0.1')");
      expect(await browserWindow.webContents.executeJavaScript('42')).to.equal(42);
    });

    // Linux and arm64 platforms (WOA and macOS) do not return any capture sources
    ifit(process.platform === 'darwin' && process.arch === 'x64')('should not make child window background transparent', async () => {
      browserWindow.webContents.setWindowOpenHandler(() => ({ action: 'allow' }));
      const didCreateWindow = once(browserWindow.webContents, 'did-create-window');
      browserWindow.webContents.executeJavaScript("window.open('about:blank') && true");
      const [childWindow] = await didCreateWindow;
      const display = screen.getPrimaryDisplay();
      childWindow.setBounds(display.bounds);
      await childWindow.webContents.executeJavaScript("const meta = document.createElement('meta'); meta.name = 'color-scheme'; meta.content = 'dark'; document.head.appendChild(meta); true;");
      await setTimeoutAsync(1000);
      const screenCapture = await ScreenCapture.createForDisplay(display);
      // color-scheme is set to dark so background should not be white
      await screenCapture.expectColorAtCenterDoesNotMatch(HexColors.WHITE);
    });
  });

  describe('custom window', () => {
    let browserWindow: BrowserWindow;

    let server: http.Server;
    let url: string;

    before(async () => {
      server = http.createServer((request, response) => {
        switch (request.url) {
          case '/index':
            response.statusCode = 200;
            response.end('<title>Index page</title>');
            break;
          case '/child':
            response.statusCode = 200;
            response.end('<title>Child page</title>');
            break;
          default:
            throw new Error(`Unsupported endpoint: ${request.url}`);
        }
      });

      url = (await listen(server)).url;
    });

    after(() => {
      server.close();
    });

    beforeEach(async () => {
      browserWindow = new BrowserWindow({ show: false });
      await browserWindow.loadURL(`${url}/index`);
    });

    afterEach(closeAllWindows);

    it('throws error when created window uses invalid webcontents', async () => {
      const listeners = process.listeners('uncaughtException');
      process.removeAllListeners('uncaughtException');
      const uncaughtExceptionEmitted = new Promise<void>((resolve, reject) => {
        process.on('uncaughtException', (thrown) => {
          try {
            expect(thrown.message).to.equal('Invalid webContents. Created window should be connected to webContents passed with options object.');
            resolve();
          } catch (e) {
            reject(e);
          } finally {
            process.removeAllListeners('uncaughtException');
            listeners.forEach((listener) => process.on('uncaughtException', listener));
          }
        });
      });

      browserWindow.webContents.setWindowOpenHandler(() => {
        return {
          action: 'allow',
          createWindow: () => {
            const childWindow = new BrowserWindow({ title: 'New window' });
            return childWindow.webContents;
          }
        };
      });

      browserWindow.webContents.executeJavaScript("window.open('about:blank', '', 'show=no') && true");

      await uncaughtExceptionEmitted;
    });

    it('spawns browser window when createWindow is provided', async () => {
      const browserWindowTitle = 'Child browser window';

      const childWindow = await new Promise<Electron.BrowserWindow>(resolve => {
        browserWindow.webContents.setWindowOpenHandler(() => {
          return {
            action: 'allow',
            createWindow: (options) => {
              const childWindow = new BrowserWindow({ ...options, title: browserWindowTitle });
              resolve(childWindow);
              return childWindow.webContents;
            }
          };
        });

        browserWindow.webContents.executeJavaScript("window.open('about:blank', '', 'show=no') && true");
      });

      expect(childWindow.title).to.equal(browserWindowTitle);
    });

    it('spawns browser window with overriden options', async () => {
      const childWindow = await new Promise<Electron.BrowserWindow>(resolve => {
        browserWindow.webContents.setWindowOpenHandler(() => {
          return {
            action: 'allow',
            overrideBrowserWindowOptions: {
              width: 640,
              height: 480
            },
            createWindow: (options) => {
              expect(options.width).to.equal(640);
              expect(options.height).to.equal(480);
              const childWindow = new BrowserWindow(options);
              resolve(childWindow);
              return childWindow.webContents;
            }
          };
        });

        browserWindow.webContents.executeJavaScript("window.open('about:blank', '', 'show=no') && true");
      });

      const size = childWindow.getSize();
      expect(size[0]).to.equal(640);
      expect(size[1]).to.equal(480);
    });

    it('spawns browser window with access to opener property', async () => {
      const childWindow = await new Promise<Electron.BrowserWindow>(resolve => {
        browserWindow.webContents.setWindowOpenHandler(() => {
          return {
            action: 'allow',
            createWindow: (options) => {
              const childWindow = new BrowserWindow(options);
              resolve(childWindow);
              return childWindow.webContents;
            }
          };
        });

        browserWindow.webContents.executeJavaScript(`window.open('${url}/child', '', 'show=no') && true`);
      });

      await once(childWindow.webContents, 'ready-to-show');
      const childWindowOpenerTitle = await childWindow.webContents.executeJavaScript('window.opener.document.title');
      expect(childWindowOpenerTitle).to.equal(browserWindow.title);
    });

    it('spawns browser window without access to opener property because of noopener attribute ', async () => {
      const childWindow = await new Promise<Electron.BrowserWindow>(resolve => {
        browserWindow.webContents.setWindowOpenHandler(() => {
          return {
            action: 'allow',
            createWindow: (options) => {
              const childWindow = new BrowserWindow(options);
              resolve(childWindow);
              return childWindow.webContents;
            }
          };
        });
        browserWindow.webContents.executeJavaScript(`window.open('${url}/child', '', 'noopener,show=no') && true`);
      });

      await once(childWindow.webContents, 'ready-to-show');
      await expect(childWindow.webContents.executeJavaScript('window.opener.document.title')).to.be.rejectedWith('Script failed to execute, this normally means an error was thrown. Check the renderer console for the error.');
    });
  });
});