feat: introduce browserType.downloadBrowserIfNeeded() (#834)

Fixes #823

docs/api.md

@@ -3478,6 +3478,7 @@ const { chromium } = require('playwright');  // Or 'firefox' or 'webkit'.
 <!-- GEN:toc -->
 - [browserType.connect(options)](#browsertypeconnectoptions)
 - [browserType.devices](#browsertypedevices)
+- [browserType.downloadBrowserIfNeeded([progress])](#browsertypedownloadbrowserifneededprogress)
 - [browserType.errors](#browsertypeerrors)
 - [browserType.executablePath()](#browsertypeexecutablepath)
 - [browserType.launch([options])](#browsertypelaunchoptions)
@@ -3516,6 +3517,12 @@ const iPhone = webkit.devices['iPhone 6'];
 })();
 ```
 
+#### browserType.downloadBrowserIfNeeded([progress])
+- `progress` <[function]> If download is initiated, this function is called with two parameters: `downloadedBytes` and `totalBytes`.
+- returns: <[Promise]> promise that resolves when browser is successfully downloaded.
+
+Download browser binary if it is missing.
+
 #### browserType.errors
 - returns: <[Object]>
   - `TimeoutError` <[function]> A class of [TimeoutError].

download-browser.js

@@ -38,7 +38,7 @@ async function downloadBrowser(browser) {
   // Do nothing if the revision is already downloaded.
   if (revisionInfo.local)
     return revisionInfo;
-  await fetcher.download(revisionInfo.revision, onProgress);
+  await browserType.downloadBrowserIfNeeded(onProgress);
   logPolitely(`${browser} downloaded to ${revisionInfo.folderPath}`);
   return revisionInfo;
 }

src/server/browserType.ts

@@ -19,6 +19,7 @@ import { TimeoutError } from '../errors';
 import { Browser, ConnectOptions } from '../browser';
 import { BrowserContext } from '../browserContext';
 import { BrowserServer } from './browserServer';
+import { OnProgressCallback } from './browserFetcher';
 
 export type BrowserArgOptions = {
   headless?: boolean,
@@ -44,6 +45,7 @@ export interface BrowserType {
   launchServer(options?: LaunchOptions & { port?: number }): Promise<BrowserServer>;
   launchPersistent(userDataDir: string, options?: LaunchOptions): Promise<BrowserContext>;
   connect(options: ConnectOptions): Promise<Browser>;
+  downloadBrowserIfNeeded(progress?: OnProgressCallback): Promise<void>;
   devices: types.Devices;
   errors: { TimeoutError: typeof TimeoutError };
 }

src/server/chromium.ts

@@ -19,7 +19,7 @@ import * as fs from 'fs';
 import * as os from 'os';
 import * as path from 'path';
 import * as util from 'util';
-import { BrowserFetcher, BrowserFetcherOptions } from '../server/browserFetcher';
+import { BrowserFetcher, OnProgressCallback, BrowserFetcherOptions } from '../server/browserFetcher';
 import { DeviceDescriptors } from '../deviceDescriptors';
 import * as types from '../types';
 import { assert } from '../helper';
@@ -194,6 +194,15 @@ export class Chromium implements BrowserType {
     return chromeArguments;
   }
 
+  async downloadBrowserIfNeeded(onProgress?: OnProgressCallback) {
+    const fetcher = this._createBrowserFetcher();
+    const revisionInfo = fetcher.revisionInfo();
+    // Do nothing if the revision is already downloaded.
+    if (revisionInfo.local)
+      return;
+    await fetcher.download(revisionInfo.revision, onProgress);
+  }
+
   _createBrowserFetcher(options: BrowserFetcherOptions = {}): BrowserFetcher {
     const downloadURLs = {
       linux: '%s/chromium-browser-snapshots/Linux_x64/%d/%s.zip',

src/server/firefox.ts

@@ -16,7 +16,7 @@
  */
 
 import { FFBrowser } from '../firefox/ffBrowser';
-import { BrowserFetcher, BrowserFetcherOptions } from './browserFetcher';
+import { BrowserFetcher, OnProgressCallback, BrowserFetcherOptions } from './browserFetcher';
 import { DeviceDescriptors } from '../deviceDescriptors';
 import { launchProcess, waitForLine } from './processLauncher';
 import * as types from '../types';
@@ -44,6 +44,15 @@ export class Firefox implements BrowserType {
     this._revision = preferredRevision;
   }
 
+  async downloadBrowserIfNeeded(onProgress?: OnProgressCallback) {
+    const fetcher = this._createBrowserFetcher();
+    const revisionInfo = fetcher.revisionInfo();
+    // Do nothing if the revision is already downloaded.
+    if (revisionInfo.local)
+      return;
+    await fetcher.download(revisionInfo.revision, onProgress);
+  }
+
   name() {
     return 'firefox';
   }

src/server/webkit.ts

@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 
-import { BrowserFetcher, BrowserFetcherOptions } from './browserFetcher';
+import { BrowserFetcher, OnProgressCallback, BrowserFetcherOptions } from './browserFetcher';
 import { DeviceDescriptors } from '../deviceDescriptors';
 import { TimeoutError } from '../errors';
 import * as types from '../types';
@@ -52,6 +52,15 @@ export class WebKit implements BrowserType {
     return 'webkit';
   }
 
+  async downloadBrowserIfNeeded(onProgress?: OnProgressCallback) {
+    const fetcher = this._createBrowserFetcher();
+    const revisionInfo = fetcher.revisionInfo();
+    // Do nothing if the revision is already downloaded.
+    if (revisionInfo.local)
+      return;
+    await fetcher.download(revisionInfo.revision, onProgress);
+  }
+
   async launch(options?: LaunchOptions & { slowMo?: number }): Promise<WKBrowser> {
     const { browserServer, transport } = await this._launchServer(options, 'local');
     const browser = await WKBrowser.connect(transport!, options && options.slowMo);