feat(download): adding a new Download._cancel method (#6236)

docs/src/api/class-download.md

@@ -62,6 +62,14 @@ downloaded content. If [`option: acceptDownloads`] is not set, download events a
 not performed and user has no access to the downloaded files.
 :::
 
+## async method: Download._cancel
+
+**Chromium-only** Cancels a download.
+Will not fail if the download is already finished or canceled.
+Upon successful cancellations, `download.failure()` would resolve to `'canceled'`.
+
+Currently **experimental** and may subject to further changes.
+
 ## async method: Download.createReadStream
 * langs: java, js, csharp
 - returns: <[null]|[Readable]>

src/client/artifact.ts

@@ -71,6 +71,12 @@ export class Artifact extends ChannelOwner<channels.ArtifactChannel, channels.Ar
     });
   }
 
+  async cancel(): Promise<void> {
+    return this._wrapApiCall(`${this._apiName}.cancel`, async (channel: channels.ArtifactChannel) => {
+      return channel.cancel();
+    });
+  }
+
   async delete(): Promise<void> {
     return this._wrapApiCall(`${this._apiName}.delete`, async (channel: channels.ArtifactChannel) => {
       return channel.delete();

src/client/download.ts

@@ -60,6 +60,10 @@ export class Download implements api.Download {
     return this._artifact.createReadStream();
   }
 
+  async _cancel(): Promise<void> {
+    return this._artifact.cancel();
+  }
+
   async delete(): Promise<void> {
     return this._artifact.delete();
   }

src/dispatchers/artifactDispatcher.ts

@@ -89,6 +89,10 @@ export class ArtifactDispatcher extends Dispatcher<Artifact, channels.ArtifactIn
     return { error: error || undefined };
   }
 
+  async cancel(): Promise<void> {
+    await this._object.cancel();
+  }
+
   async delete(): Promise<void> {
     await this._object.delete();
     this._dispose();

src/protocol/channels.ts

@@ -2480,6 +2480,7 @@ export interface ArtifactChannel extends Channel {
   saveAsStream(params?: ArtifactSaveAsStreamParams, metadata?: Metadata): Promise<ArtifactSaveAsStreamResult>;
   failure(params?: ArtifactFailureParams, metadata?: Metadata): Promise<ArtifactFailureResult>;
   stream(params?: ArtifactStreamParams, metadata?: Metadata): Promise<ArtifactStreamResult>;
+  cancel(params?: ArtifactCancelParams, metadata?: Metadata): Promise<ArtifactCancelResult>;
   delete(params?: ArtifactDeleteParams, metadata?: Metadata): Promise<ArtifactDeleteResult>;
 }
 export type ArtifactPathAfterFinishedParams = {};
@@ -2509,6 +2510,9 @@ export type ArtifactStreamOptions = {};
 export type ArtifactStreamResult = {
   stream?: StreamChannel,
 };
+export type ArtifactCancelParams = {};
+export type ArtifactCancelOptions = {};
+export type ArtifactCancelResult = void;
 export type ArtifactDeleteParams = {};
 export type ArtifactDeleteOptions = {};
 export type ArtifactDeleteResult = void;

src/protocol/protocol.yml

@@ -2043,6 +2043,8 @@ Artifact:
       returns:
         stream: Stream?
 
+    cancel:
+
     delete:
 
 

src/protocol/validator.ts

@@ -960,6 +960,7 @@ export function createScheme(tChannel: (name: string) => Validator): Scheme {
   scheme.ArtifactSaveAsStreamParams = tOptional(tObject({}));
   scheme.ArtifactFailureParams = tOptional(tObject({}));
   scheme.ArtifactStreamParams = tOptional(tObject({}));
+  scheme.ArtifactCancelParams = tOptional(tObject({}));
   scheme.ArtifactDeleteParams = tOptional(tObject({}));
   scheme.StreamReadParams = tObject({
     size: tOptional(tNumber),

src/server/artifact.ts

@@ -15,24 +15,28 @@
  */
 
 import fs from 'fs';
+import { assert } from '../utils/utils';
 import { SdkObject } from './instrumentation';
 
 type SaveCallback = (localPath: string, error?: string) => Promise<void>;
+type CancelCallback = () => Promise<void>;
 
 export class Artifact extends SdkObject {
   private _localPath: string;
   private _unaccessibleErrorMessage: string | undefined;
+  private _cancelCallback: CancelCallback | undefined;
   private _finishedCallback: () => void;
   private _finishedPromise: Promise<void>;
   private _saveCallbacks: SaveCallback[] = [];
   private _finished: boolean = false;
   private _deleted = false;
   private _failureError: string | null = null;
 
-  constructor(parent: SdkObject, localPath: string, unaccessibleErrorMessage?: string) {
+  constructor(parent: SdkObject, localPath: string, unaccessibleErrorMessage?: string, cancelCallback?: CancelCallback) {
     super(parent, 'artifact');
     this._localPath = localPath;
     this._unaccessibleErrorMessage = unaccessibleErrorMessage;
+    this._cancelCallback = cancelCallback;
     this._finishedCallback = () => {};
     this._finishedPromise = new Promise(f => this._finishedCallback = f);
   }
@@ -76,6 +80,11 @@ export class Artifact extends SdkObject {
     return this._failureError;
   }
 
+  async cancel(): Promise<void> {
+    assert(this._cancelCallback !== undefined);
+    return this._cancelCallback();
+  }
+
   async delete(): Promise<void> {
     if (this._unaccessibleErrorMessage)
       return;

src/server/browserContext.ts

@@ -152,6 +152,7 @@ export abstract class BrowserContext extends SdkObject {
   abstract _doUpdateRequestInterception(): Promise<void>;
   abstract _doClose(): Promise<void>;
   abstract _onClosePersistent(): Promise<void>;
+  abstract _doCancelDownload(uuid: string): Promise<void>;
 
   async cookies(urls: string | string[] | undefined = []): Promise<types.NetworkCookie[]> {
     if (urls && !Array.isArray(urls))

src/server/chromium/crBrowser.ts

@@ -479,6 +479,16 @@ export class CRBrowserContext extends BrowserContext {
     }
   }
 
+  async _doCancelDownload(guid: string) {
+    // The upstream CDP method is implemented in a way that no explicit error would be given
+    // regarding the requested `guid`, even if the download is in a state not suitable for
+    // cancellation (finished, cancelled, etc.) or the guid is invalid at all.
+    await this._browser._session.send('Browser.cancelDownload', {
+      guid: guid,
+      browserContextId: this._browserContextId,
+    });
+  }
+
   backgroundPages(): Page[] {
     const result: Page[] = [];
     for (const backgroundPage of this._browser._backgroundPages.values()) {

src/server/download.ts

@@ -27,7 +27,9 @@ export class Download {
 
   constructor(page: Page, downloadsPath: string, uuid: string, url: string, suggestedFilename?: string) {
     const unaccessibleErrorMessage = !page._browserContext._options.acceptDownloads ? 'Pass { acceptDownloads: true } when you are creating your browser context.' : undefined;
-    this.artifact = new Artifact(page, path.join(downloadsPath, uuid), unaccessibleErrorMessage);
+    this.artifact = new Artifact(page, path.join(downloadsPath, uuid), unaccessibleErrorMessage, () => {
+      return this._page._browserContext._doCancelDownload(uuid);
+    });
     this._page = page;
     this.url = url;
     this._suggestedFilename = suggestedFilename;

src/server/firefox/ffBrowser.ts

@@ -330,6 +330,11 @@ export class FFBrowserContext extends BrowserContext {
     await this._browser._connection.send('Browser.removeBrowserContext', { browserContextId: this._browserContextId });
     this._browser._contexts.delete(this._browserContextId);
   }
+
+  async _doCancelDownload(uuid: string) {
+    // TODO: Have this implemented
+    throw new Error('Download cancellation not yet implemented in Firefox');
+  }
 }
 
 function toJugglerProxyOptions(proxy: types.ProxySettings) {

src/server/webkit/wkBrowser.ts

@@ -326,4 +326,9 @@ export class WKBrowserContext extends BrowserContext {
     await this._browser._browserSession.send('Playwright.deleteContext', { browserContextId: this._browserContextId });
     this._browser._contexts.delete(this._browserContextId);
   }
+
+  async _doCancelDownload(uuid: string) {
+    // TODO: Have this implemented
+    throw new Error('Download cancellation not yet implemented in WebKit');
+  }
 }

tests/config/checkCoverage.js

@@ -45,6 +45,7 @@ if (browserName !== 'chromium') {
   api.delete('coverage.startCSSCoverage');
   api.delete('coverage.stopCSSCoverage');
   api.delete('page.pdf');
+  api.delete('download._cancel');
 }
 
 // Some permissions tests are disabled in webkit. See permissions.jest.js

tests/download.spec.ts

@@ -31,6 +31,14 @@ it.describe('download event', () => {
       res.setHeader('Content-Disposition', 'attachment; filename=file.txt');
       res.end(`Hello world`);
     });
+    server.setRoute('/downloadWithDelay', (req, res) => {
+      res.setHeader('Content-Type', 'application/octet-stream');
+      res.setHeader('Content-Disposition', 'attachment; filename=file.txt');
+      // Chromium requires a large enough payload to trigger the download event soon enough
+      res.write('a'.repeat(4096));
+      res.write('foo');
+      res.uncork();
+    });
   });
 
   it('should report downloads with acceptDownloads: false', async ({browser, server}) => {
@@ -461,6 +469,41 @@ it.describe('download event', () => {
     await page.close();
   });
 
+  it('should be able to cancel pending downloads', async ({browser, server, browserName, browserVersion}) => {
+    // The exact upstream change is in b449b5c, which still does not appear in the first few 91.* tags until 91.0.4437.0.
+    it.fixme(browserName === 'chromium' && Number(browserVersion.split('.')[0]) < 91, 'The upstream Browser.cancelDownload command is not available before Chrome 91');
+    it.fixme(browserName !== 'chromium', 'Download cancellation currently implemented for only Chromium');
+    const page = await browser.newPage({ acceptDownloads: true });
+    await page.setContent(`<a href="${server.PREFIX}/downloadWithDelay">download</a>`);
+    const [ download ] = await Promise.all([
+      page.waitForEvent('download'),
+      page.click('a')
+    ]);
+    await download._cancel();
+    const failure = await download.failure();
+    expect(failure).toBe('canceled');
+    await page.close();
+  });
+
+  it('should not fail explicitly to cancel a download even if that is already finished', async ({browser, server, browserName, browserVersion}) => {
+    // The exact upstream change is in b449b5c, which still does not appear in the first few 91.* tags until 91.0.4437.0.
+    it.fixme(browserName === 'chromium' && Number(browserVersion.split('.')[0]) < 91, 'The upstream Browser.cancelDownload command is not available before Chrome 91');
+    it.fixme(browserName !== 'chromium', 'Download cancellation currently implemented for only Chromium');
+    const page = await browser.newPage({ acceptDownloads: true });
+    await page.setContent(`<a href="${server.PREFIX}/download">download</a>`);
+    const [ download ] = await Promise.all([
+      page.waitForEvent('download'),
+      page.click('a')
+    ]);
+    const path = await download.path();
+    expect(fs.existsSync(path)).toBeTruthy();
+    expect(fs.readFileSync(path).toString()).toBe('Hello world');
+    await download._cancel();
+    const failure = await download.failure();
+    expect(failure).toBe(null);
+    await page.close();
+  });
+
   it('should report downloads with interception', async ({browser, server}) => {
     const page = await browser.newPage({ acceptDownloads: true });
     await page.route(/.*/, r => r.continue());
@@ -474,5 +517,4 @@ it.describe('download event', () => {
     expect(fs.readFileSync(path).toString()).toBe('Hello world');
     await page.close();
   });
-
 });

types/types.d.ts

@@ -9495,6 +9495,14 @@ export interface Dialog {
  * performed and user has no access to the downloaded files.
  */
 export interface Download {
+  /**
+   * **Chromium-only** Cancels a download. Will not fail if the download is already finished or canceled. Upon successful
+   * cancellations, `download.failure()` would resolve to `'canceled'`.
+   *
+   * Currently **experimental** and may subject to further changes.
+   */
+  _cancel(): Promise<void>;
+
   /**
    * Returns readable stream for current download or `null` if download failed.
    */

utils/doclint/missingDocs.js

@@ -78,6 +78,9 @@ function paramsForMember(member) {
   return new Set(member.argsArray.map(a => a.alias));
 }
 
+// Including experimental method names (with a leading underscore) that would be otherwise skipped
+const allowExperimentalMethods = new Set([ 'Download._cancel' ]);
+
 /**
  * @param {string[]} rootNames
  */
@@ -109,6 +112,20 @@ function listMethods(rootNames, apiFileName) {
     return null;
   }
 
+  /**
+   * @param {string} className
+   * @param {string} methodName
+   */
+  function shouldSkipMethodByName(className, methodName) {
+    if (allowExperimentalMethods.has(`${className}.${methodName}`))
+      return false;
+    if (methodName.startsWith('_') || methodName === 'T' || methodName === 'toString')
+      return true;
+    if (/** @type {any} */(EventEmitter).prototype.hasOwnProperty(methodName))
+      return true;
+    return false;
+  }
+
   /**
    * @param {string} className
    * @param {!ts.Type} classType
@@ -120,9 +137,7 @@ function listMethods(rootNames, apiFileName) {
       apiMethods.set(className, methods);
     }
     for (const [name, member] of /** @type {any[]} */(classType.symbol.members || [])) {
-      if (name.startsWith('_') || name === 'T' || name === 'toString')
-        continue;
-      if (/** @type {any} */(EventEmitter).prototype.hasOwnProperty(name))
+      if (shouldSkipMethodByName(className, name))
         continue;
       const memberType = checker.getTypeOfSymbolAtLocation(member, member.valueDeclaration);
       const signature = signatureForType(memberType);