chore: stop using console.assert everywhere (#2646)

Since Node 10, `console.assert` no longer throws an AssertionError.
(This is generally good since it aligns Node.js with Browsers.)

This patch migrates all usages of `console.assert` in our codebase.
- All the `lib/` and testing code is migrated onto a handmade `assert`
function. This is to make Puppeteer transpilation / bundling easier.
- All the tooling is switched to use Node's `assert` module.

Fixes #2547.

lib/Browser.js

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-const { helper } = require('./helper');
+const { helper, assert } = require('./helper');
 const Target = require('./Target');
 const EventEmitter = require('events');
 const TaskQueue = require('./TaskQueue');
@@ -108,7 +108,7 @@ class Browser extends EventEmitter {
     const context = (browserContextId && this._contexts.has(browserContextId)) ? this._contexts.get(browserContextId) : this._defaultContext;
 
     const target = new Target(targetInfo, context, () => this._connection.createSession(targetInfo.targetId), this._ignoreHTTPSErrors, this._setDefaultViewport, this._screenshotTaskQueue);
-    console.assert(!this._targets.has(event.targetInfo.targetId), 'Target should not exist before targetCreated');
+    assert(!this._targets.has(event.targetInfo.targetId), 'Target should not exist before targetCreated');
     this._targets.set(event.targetInfo.targetId, target);
 
     if (await target._initializedPromise) {
@@ -136,7 +136,7 @@ class Browser extends EventEmitter {
    */
   _targetInfoChanged(event) {
     const target = this._targets.get(event.targetInfo.targetId);
-    console.assert(target, 'target should exist before targetInfoChanged');
+    assert(target, 'target should exist before targetInfoChanged');
     const previousURL = target.url();
     const wasInitialized = target._isInitialized;
     target._targetInfoChanged(event.targetInfo);
@@ -167,7 +167,7 @@ class Browser extends EventEmitter {
   async _createPageInContext(contextId) {
     const {targetId} = await this._connection.send('Target.createTarget', {url: 'about:blank', browserContextId: contextId || undefined});
     const target = await this._targets.get(targetId);
-    console.assert(await target._initializedPromise, 'Failed to create target for page');
+    assert(await target._initializedPromise, 'Failed to create target for page');
     const page = await target.page();
     return page;
   }
@@ -268,7 +268,7 @@ class BrowserContext extends EventEmitter {
   }
 
   async close() {
-    console.assert(this._id, 'Non-incognito profiles cannot be closed!');
+    assert(this._id, 'Non-incognito profiles cannot be closed!');
     await this._browser._disposeContext(this._id);
   }
 }

lib/BrowserFetcher.js

@@ -20,7 +20,7 @@ const path = require('path');
 const extract = require('extract-zip');
 const util = require('util');
 const URL = require('url');
-const {helper} = require('./helper');
+const {helper, assert} = require('./helper');
 const removeRecursive = require('rimraf');
 // @ts-ignore
 const ProxyAgent = require('https-proxy-agent');
@@ -63,10 +63,10 @@ class BrowserFetcher {
         this._platform = 'linux';
       else if (platform === 'win32')
         this._platform = os.arch() === 'x64' ? 'win64' : 'win32';
-      console.assert(this._platform, 'Unsupported platform: ' + os.platform());
+      assert(this._platform, 'Unsupported platform: ' + os.platform());
     }
     const supportedPlatforms = ['mac', 'linux', 'win32', 'win64'];
-    console.assert(supportedPlatforms.includes(this._platform), 'Unsupported platform: ' + this._platform);
+    assert(supportedPlatforms.includes(this._platform), 'Unsupported platform: ' + this._platform);
   }
 
   /**
@@ -138,7 +138,7 @@ class BrowserFetcher {
    */
   async remove(revision) {
     const folderPath = this._getFolderPath(revision);
-    console.assert(await existsAsync(folderPath), `Failed to remove: revision ${revision} is not downloaded`);
+    assert(await existsAsync(folderPath), `Failed to remove: revision ${revision} is not downloaded`);
     await new Promise(fulfill => removeRecursive(folderPath, fulfill));
   }
 

lib/Connection.js

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-const {helper} = require('./helper');
+const {helper, assert} = require('./helper');
 const debugProtocol = require('debug')('puppeteer:protocol');
 const debugSession = require('debug')('puppeteer:session');
 
@@ -228,7 +228,7 @@ class CDPSession extends EventEmitter {
           this._sessions.delete(object.params.sessionId);
         }
       }
-      console.assert(!object.id);
+      assert(!object.id);
       this.emit(object.method, object.params);
     }
   }

lib/Coverage.js

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-const {helper, debugError} = require('./helper');
+const {helper, debugError, assert} = require('./helper');
 
 /**
  * @typedef {Object} CoverageEntry
@@ -81,7 +81,7 @@ class JSCoverage {
    * @param {!Object} options
    */
   async start(options = {}) {
-    console.assert(!this._enabled, 'JSCoverage is already enabled');
+    assert(!this._enabled, 'JSCoverage is already enabled');
     this._resetOnNavigation = options.resetOnNavigation === undefined ? true : !!options.resetOnNavigation;
     this._enabled = true;
     this._scriptURLs.clear();
@@ -126,7 +126,7 @@ class JSCoverage {
    * @return {!Promise<!Array<!CoverageEntry>>}
    */
   async stop() {
-    console.assert(this._enabled, 'JSCoverage is not enabled');
+    assert(this._enabled, 'JSCoverage is not enabled');
     this._enabled = false;
     const [profileResponse] = await Promise.all([
       this._client.send('Profiler.takePreciseCoverage'),
@@ -169,7 +169,7 @@ class CSSCoverage {
    * @param {!Object} options
    */
   async start(options = {}) {
-    console.assert(!this._enabled, 'CSSCoverage is already enabled');
+    assert(!this._enabled, 'CSSCoverage is already enabled');
     this._resetOnNavigation = options.resetOnNavigation === undefined ? true : !!options.resetOnNavigation;
     this._enabled = true;
     this._stylesheetURLs.clear();
@@ -214,7 +214,7 @@ class CSSCoverage {
    * @return {!Promise<!Array<!CoverageEntry>>}
    */
   async stop() {
-    console.assert(this._enabled, 'CSSCoverage is not enabled');
+    assert(this._enabled, 'CSSCoverage is not enabled');
     this._enabled = false;
     const [ruleTrackingResponse] = await Promise.all([
       this._client.send('CSS.stopRuleUsageTracking'),

lib/Dialog.js

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-const {helper} = require('./helper');
+const {helper, assert} = require('./helper');
 
 class Dialog {
   /**
@@ -56,7 +56,7 @@ class Dialog {
    * @param {string=} promptText
    */
   async accept(promptText) {
-    console.assert(!this._handled, 'Cannot accept dialog which is already handled!');
+    assert(!this._handled, 'Cannot accept dialog which is already handled!');
     this._handled = true;
     await this._client.send('Page.handleJavaScriptDialog', {
       accept: true,
@@ -65,7 +65,7 @@ class Dialog {
   }
 
   async dismiss() {
-    console.assert(!this._handled, 'Cannot dismiss dialog which is already handled!');
+    assert(!this._handled, 'Cannot dismiss dialog which is already handled!');
     this._handled = true;
     await this._client.send('Page.handleJavaScriptDialog', {
       accept: false

lib/ExecutionContext.js

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-const {helper} = require('./helper');
+const {helper, assert} = require('./helper');
 
 class ExecutionContext {
   /**
@@ -123,8 +123,8 @@ class ExecutionContext {
    * @return {!Promise<!JSHandle>}
    */
   async queryObjects(prototypeHandle) {
-    console.assert(!prototypeHandle._disposed, 'Prototype JSHandle is disposed!');
+    assert(!prototypeHandle._disposed, 'Prototype JSHandle is disposed!');
-    console.assert(prototypeHandle._remoteObject.objectId, 'Prototype JSHandle must not be referencing primitive value');
+    assert(prototypeHandle._remoteObject.objectId, 'Prototype JSHandle must not be referencing primitive value');
     const response = await this._client.send('Runtime.queryObjects', {
       prototypeObjectId: prototypeHandle._remoteObject.objectId
     });

lib/FrameManager.js

@@ -16,7 +16,7 @@
 
 const fs = require('fs');
 const EventEmitter = require('events');
-const {helper} = require('./helper');
+const {helper, assert} = require('./helper');
 const {ExecutionContext, JSHandle} = require('./ExecutionContext');
 const ElementHandle = require('./ElementHandle');
 
@@ -116,7 +116,7 @@ class FrameManager extends EventEmitter {
   _onFrameAttached(frameId, parentFrameId) {
     if (this._frames.has(frameId))
       return;
-    console.assert(parentFrameId);
+    assert(parentFrameId);
     const parentFrame = this._frames.get(parentFrameId);
     const frame = new Frame(this._client, this._page, parentFrame, frameId);
     this._frames.set(frame._id, frame);
@@ -129,7 +129,7 @@ class FrameManager extends EventEmitter {
   _onFrameNavigated(framePayload) {
     const isMainFrame = !framePayload.parentId;
     let frame = isMainFrame ? this._mainFrame : this._frames.get(framePayload.id);
-    console.assert(isMainFrame || frame, 'We either navigate top level or have old version of the navigated frame');
+    assert(isMainFrame || frame, 'We either navigate top level or have old version of the navigated frame');
 
     // Detach all child frames first.
     if (frame) {
@@ -220,7 +220,7 @@ class FrameManager extends EventEmitter {
    */
   createJSHandle(contextId, remoteObject) {
     const context = this._contextIdToContext.get(contextId);
-    console.assert(context, 'INTERNAL ERROR: missing context with id = ' + contextId);
+    assert(context, 'INTERNAL ERROR: missing context with id = ' + contextId);
     if (remoteObject.subtype === 'node')
       return new ElementHandle(context, this._client, remoteObject, this._page, this);
     return new JSHandle(context, this._client, remoteObject);
@@ -588,7 +588,7 @@ class Frame {
    */
   async click(selector, options = {}) {
     const handle = await this.$(selector);
-    console.assert(handle, 'No node found for selector: ' + selector);
+    assert(handle, 'No node found for selector: ' + selector);
     await handle.click(options);
     await handle.dispose();
   }
@@ -598,7 +598,7 @@ class Frame {
    */
   async focus(selector) {
     const handle = await this.$(selector);
-    console.assert(handle, 'No node found for selector: ' + selector);
+    assert(handle, 'No node found for selector: ' + selector);
     await handle.focus();
     await handle.dispose();
   }
@@ -608,7 +608,7 @@ class Frame {
    */
   async hover(selector) {
     const handle = await this.$(selector);
-    console.assert(handle, 'No node found for selector: ' + selector);
+    assert(handle, 'No node found for selector: ' + selector);
     await handle.hover();
     await handle.dispose();
   }
@@ -620,7 +620,7 @@ class Frame {
   */
   select(selector, ...values){
     for (const value of values)
-      console.assert(helper.isString(value), 'Values must be strings. Found value "' + value + '" of type "' + (typeof value) + '"');
+      assert(helper.isString(value), 'Values must be strings. Found value "' + value + '" of type "' + (typeof value) + '"');
     return this.$eval(selector, (element, values) => {
       if (element.nodeName.toLowerCase() !== 'select')
         throw new Error('Element is not a <select> element.');
@@ -643,7 +643,7 @@ class Frame {
    */
   async tap(selector) {
     const handle = await this.$(selector);
-    console.assert(handle, 'No node found for selector: ' + selector);
+    assert(handle, 'No node found for selector: ' + selector);
     await handle.tap();
     await handle.dispose();
   }
@@ -655,7 +655,7 @@ class Frame {
    */
   async type(selector, text, options) {
     const handle = await this.$(selector);
-    console.assert(handle, 'No node found for selector: ' + selector);
+    assert(handle, 'No node found for selector: ' + selector);
     await handle.type(text, options);
     await handle.dispose();
   }
@@ -818,9 +818,9 @@ class WaitTask {
    */
   constructor(frame, predicateBody, title, polling, timeout, ...args) {
     if (helper.isString(polling))
-      console.assert(polling === 'raf' || polling === 'mutation', 'Unknown polling option: ' + polling);
+      assert(polling === 'raf' || polling === 'mutation', 'Unknown polling option: ' + polling);
     else if (helper.isNumber(polling))
-      console.assert(polling > 0, 'Cannot poll with non-positive interval: ' + polling);
+      assert(polling > 0, 'Cannot poll with non-positive interval: ' + polling);
     else
       throw new Error('Unknown polling options: ' + polling);
 

lib/Input.js

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-const {helper} = require('./helper');
+const {helper, assert} = require('./helper');
 const keyDefinitions = require('./USKeyboardLayout');
 
 /**
@@ -93,7 +93,7 @@ class Keyboard {
     };
 
     const definition = keyDefinitions[keyString];
-    console.assert(definition, `Unknown key: "${keyString}"`);
+    assert(definition, `Unknown key: "${keyString}"`);
 
     if (definition.key)
       description.key = definition.key;

lib/Launcher.js

@@ -22,7 +22,7 @@ const {Connection} = require('./Connection');
 const {Browser} = require('./Browser');
 const readline = require('readline');
 const fs = require('fs');
-const {helper, debugError} = require('./helper');
+const {helper, assert, debugError} = require('./helper');
 const ChromiumRevision = require(path.join(helper.projectRoot(), 'package.json')).puppeteer.chromium_revision;
 
 const mkdtempAsync = helper.promisify(fs.mkdtemp);
@@ -60,7 +60,7 @@ class Launcher {
    */
   static async launch(options) {
     options = Object.assign({}, options || {});
-    console.assert(!options.ignoreDefaultArgs || !options.appMode, '`appMode` flag cannot be used together with `ignoreDefaultArgs`');
+    assert(!options.ignoreDefaultArgs || !options.appMode, '`appMode` flag cannot be used together with `ignoreDefaultArgs`');
     let temporaryUserDataDir = null;
     const chromeArguments = [];
     if (!options.ignoreDefaultArgs)
@@ -100,7 +100,7 @@ class Launcher {
     if (typeof chromeExecutable !== 'string') {
       const browserFetcher = new BrowserFetcher();
       const revisionInfo = browserFetcher.revisionInfo(ChromiumRevision);
-      console.assert(revisionInfo.local, `Chromium revision is not downloaded. Run "npm install" or "yarn install"`);
+      assert(revisionInfo.local, `Chromium revision is not downloaded. Run "npm install" or "yarn install"`);
       chromeExecutable = revisionInfo.executablePath;
     }
     if (Array.isArray(options.args))

lib/NavigatorWatcher.js

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 
-const {helper} = require('./helper');
+const {helper, assert} = require('./helper');
 const {FrameManager} = require('./FrameManager');
 
 class NavigatorWatcher {
@@ -25,9 +25,9 @@ class NavigatorWatcher {
    * @param {!Object=} options
    */
   constructor(frameManager, frame, timeout, options = {}) {
-    console.assert(options.networkIdleTimeout === undefined, 'ERROR: networkIdleTimeout option is no longer supported.');
+    assert(options.networkIdleTimeout === undefined, 'ERROR: networkIdleTimeout option is no longer supported.');
-    console.assert(options.networkIdleInflight === undefined, 'ERROR: networkIdleInflight option is no longer supported.');
+    assert(options.networkIdleInflight === undefined, 'ERROR: networkIdleInflight option is no longer supported.');
-    console.assert(options.waitUntil !== 'networkidle', 'ERROR: "networkidle" option is no longer supported. Use "networkidle2" instead');
+    assert(options.waitUntil !== 'networkidle', 'ERROR: "networkidle" option is no longer supported. Use "networkidle2" instead');
     let waitUntil = ['load'];
     if (Array.isArray(options.waitUntil))
       waitUntil = options.waitUntil.slice();
@@ -35,7 +35,7 @@ class NavigatorWatcher {
       waitUntil = [options.waitUntil];
     this._expectedLifecycle = waitUntil.map(value => {
       const protocolEvent = puppeteerToProtocolLifecycle[value];
-      console.assert(protocolEvent, 'Unknown value for options.waitUntil: ' + value);
+      assert(protocolEvent, 'Unknown value for options.waitUntil: ' + value);
       return protocolEvent;
     });
 

lib/NetworkManager.js

@@ -14,7 +14,7 @@
  * limitations under the License.
  */
 const EventEmitter = require('events');
-const {helper, debugError} = require('./helper');
+const {helper, assert, debugError} = require('./helper');
 const Multimap = require('./Multimap');
 
 class NetworkManager extends EventEmitter {
@@ -69,7 +69,7 @@ class NetworkManager extends EventEmitter {
     this._extraHTTPHeaders = {};
     for (const key of Object.keys(extraHTTPHeaders)) {
       const value = extraHTTPHeaders[key];
-      console.assert(helper.isString(value), `Expected value of header "${key}" to be String, but "${typeof value}" is found.`);
+      assert(helper.isString(value), `Expected value of header "${key}" to be String, but "${typeof value}" is found.`);
       this._extraHTTPHeaders[key.toLowerCase()] = value;
     }
     await this._client.send('Network.setExtraHTTPHeaders', { headers: this._extraHTTPHeaders });
@@ -407,8 +407,8 @@ class Request {
    * @param {!Object=} overrides
    */
   async continue(overrides = {}) {
-    console.assert(this._allowInterception, 'Request Interception is not enabled!');
+    assert(this._allowInterception, 'Request Interception is not enabled!');
-    console.assert(!this._interceptionHandled, 'Request is already handled!');
+    assert(!this._interceptionHandled, 'Request is already handled!');
     this._interceptionHandled = true;
     await this._client.send('Network.continueInterceptedRequest', {
       interceptionId: this._interceptionId,
@@ -430,8 +430,8 @@ class Request {
     // Mocking responses for dataURL requests is not currently supported.
     if (this._url.startsWith('data:'))
       return;
-    console.assert(this._allowInterception, 'Request Interception is not enabled!');
+    assert(this._allowInterception, 'Request Interception is not enabled!');
-    console.assert(!this._interceptionHandled, 'Request is already handled!');
+    assert(!this._interceptionHandled, 'Request is already handled!');
     this._interceptionHandled = true;
 
     const responseBody = response.body && helper.isString(response.body) ? Buffer.from(/** @type {string} */(response.body)) : /** @type {?Buffer} */(response.body || null);
@@ -476,9 +476,9 @@ class Request {
    */
   async abort(errorCode = 'failed') {
     const errorReason = errorReasons[errorCode];
-    console.assert(errorReason, 'Unknown error code: ' + errorCode);
+    assert(errorReason, 'Unknown error code: ' + errorCode);
-    console.assert(this._allowInterception, 'Request Interception is not enabled!');
+    assert(this._allowInterception, 'Request Interception is not enabled!');
-    console.assert(!this._interceptionHandled, 'Request is already handled!');
+    assert(!this._interceptionHandled, 'Request is already handled!');
     this._interceptionHandled = true;
     await this._client.send('Network.continueInterceptedRequest', {
       interceptionId: this._interceptionId,

lib/Page.js

@@ -24,7 +24,7 @@ const EmulationManager = require('./EmulationManager');
 const {FrameManager} = require('./FrameManager');
 const {Keyboard, Mouse, Touchscreen} = require('./Input');
 const Tracing = require('./Tracing');
-const {helper, debugError} = require('./helper');
+const {helper, debugError, assert} = require('./helper');
 const {Coverage} = require('./Coverage');
 const Worker = require('./Worker');
 
@@ -346,11 +346,11 @@ class Page extends EventEmitter {
       const item = Object.assign({}, cookie);
       if (!item.url && startsWithHTTP)
         item.url = pageURL;
-      console.assert(
+      assert(
           item.url !== 'about:blank',
           `Blank page can not have cookie "${item.name}"`
       );
-      console.assert(
+      assert(
           !String.prototype.startsWith.call(item.url || '', 'data:'),
           `Data URL page can not have cookie "${item.name}"`
       );
@@ -510,7 +510,7 @@ class Page extends EventEmitter {
       dialogType = Dialog.Type.Prompt;
     else if (event.type === 'beforeunload')
       dialogType = Dialog.Type.BeforeUnload;
-    console.assert(dialogType, 'Unknown javascript dialog type: ' + event.type);
+    assert(dialogType, 'Unknown javascript dialog type: ' + event.type);
     const dialog = new Dialog(this._client, dialogType, event.message, event.defaultPrompt);
     this.emit(Page.Events.Dialog, dialog);
   }
@@ -680,7 +680,7 @@ class Page extends EventEmitter {
    * @param {?string} mediaType
    */
   async emulateMedia(mediaType) {
-    console.assert(mediaType === 'screen' || mediaType === 'print' || mediaType === null, 'Unsupported media type: ' + mediaType);
+    assert(mediaType === 'screen' || mediaType === 'print' || mediaType === null, 'Unsupported media type: ' + mediaType);
     await this._client.send('Emulation.setEmulatedMedia', {media: mediaType || ''});
   }
 
@@ -736,7 +736,7 @@ class Page extends EventEmitter {
     // options.type takes precedence over inferring the type from options.path
     // because it may be a 0-length file with no extension created beforehand (i.e. as a temp file).
     if (options.type) {
-      console.assert(options.type === 'png' || options.type === 'jpeg', 'Unknown options.type value: ' + options.type);
+      assert(options.type === 'png' || options.type === 'jpeg', 'Unknown options.type value: ' + options.type);
       screenshotType = options.type;
     } else if (options.path) {
       const mimeType = mime.getType(options.path);
@@ -744,24 +744,24 @@ class Page extends EventEmitter {
         screenshotType = 'png';
       else if (mimeType === 'image/jpeg')
         screenshotType = 'jpeg';
-      console.assert(screenshotType, 'Unsupported screenshot mime type: ' + mimeType);
+      assert(screenshotType, 'Unsupported screenshot mime type: ' + mimeType);
     }
 
     if (!screenshotType)
       screenshotType = 'png';
 
     if (options.quality) {
-      console.assert(screenshotType === 'jpeg', 'options.quality is unsupported for the ' + screenshotType + ' screenshots');
+      assert(screenshotType === 'jpeg', 'options.quality is unsupported for the ' + screenshotType + ' screenshots');
-      console.assert(typeof options.quality === 'number', 'Expected options.quality to be a number but found ' + (typeof options.quality));
+      assert(typeof options.quality === 'number', 'Expected options.quality to be a number but found ' + (typeof options.quality));
-      console.assert(Number.isInteger(options.quality), 'Expected options.quality to be an integer');
+      assert(Number.isInteger(options.quality), 'Expected options.quality to be an integer');
-      console.assert(options.quality >= 0 && options.quality <= 100, 'Expected options.quality to be between 0 and 100 (inclusive), got ' + options.quality);
+      assert(options.quality >= 0 && options.quality <= 100, 'Expected options.quality to be between 0 and 100 (inclusive), got ' + options.quality);
     }
-    console.assert(!options.clip || !options.fullPage, 'options.clip and options.fullPage are exclusive');
+    assert(!options.clip || !options.fullPage, 'options.clip and options.fullPage are exclusive');
     if (options.clip) {
-      console.assert(typeof options.clip.x === 'number', 'Expected options.clip.x to be a number but found ' + (typeof options.clip.x));
+      assert(typeof options.clip.x === 'number', 'Expected options.clip.x to be a number but found ' + (typeof options.clip.x));
-      console.assert(typeof options.clip.y === 'number', 'Expected options.clip.y to be a number but found ' + (typeof options.clip.y));
+      assert(typeof options.clip.y === 'number', 'Expected options.clip.y to be a number but found ' + (typeof options.clip.y));
-      console.assert(typeof options.clip.width === 'number', 'Expected options.clip.width to be a number but found ' + (typeof options.clip.width));
+      assert(typeof options.clip.width === 'number', 'Expected options.clip.width to be a number but found ' + (typeof options.clip.width));
-      console.assert(typeof options.clip.height === 'number', 'Expected options.clip.height to be a number but found ' + (typeof options.clip.height));
+      assert(typeof options.clip.height === 'number', 'Expected options.clip.height to be a number but found ' + (typeof options.clip.height));
     }
     return this._screenshotTaskQueue.postTask(this._screenshotTask.bind(this, screenshotType, options));
   }
@@ -824,7 +824,7 @@ class Page extends EventEmitter {
     let paperHeight = 11;
     if (options.format) {
       const format = Page.PaperFormats[options.format.toLowerCase()];
-      console.assert(format, 'Unknown paper format: ' + options.format);
+      assert(format, 'Unknown paper format: ' + options.format);
       paperWidth = format.width;
       paperHeight = format.height;
     } else {
@@ -870,7 +870,7 @@ class Page extends EventEmitter {
    * @param {!{runBeforeUnload: (boolean|undefined)}=} options
    */
   async close(options = {runBeforeUnload: undefined}) {
-    console.assert(!!this._client._connection, 'Protocol error: Connection closed. Most likely the page has been closed.');
+    assert(!!this._client._connection, 'Protocol error: Connection closed. Most likely the page has been closed.');
     const runBeforeUnload = !!options.runBeforeUnload;
     if (runBeforeUnload) {
       await this._client.send('Page.close');
@@ -1043,7 +1043,7 @@ function convertPrintParameterToInches(parameter) {
       valueText = text;
     }
     const value = Number(valueText);
-    console.assert(!isNaN(value), 'Failed to parse parameter value: ' + text);
+    assert(!isNaN(value), 'Failed to parse parameter value: ' + text);
     pixels = value * unitToPixels[unit];
   } else {
     throw new Error('page.pdf() Cannot handle parameter type: ' + (typeof parameter));

lib/Tracing.js

@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-const {helper} = require('./helper');
+const {helper, assert} = require('./helper');
 const fs = require('fs');
 
 const openAsync = helper.promisify(fs.open);
@@ -34,7 +34,7 @@ class Tracing {
    * @param {!Object} options
    */
   async start(options) {
-    console.assert(!this._recording, 'Cannot start recording trace while already recording trace.');
+    assert(!this._recording, 'Cannot start recording trace while already recording trace.');
 
     const defaultCategories = [
       '-*', 'devtools.timeline', 'v8.execute', 'disabled-by-default-devtools.timeline',

lib/helper.js

@@ -28,7 +28,7 @@ class Helper {
    */
   static evaluationString(fun, ...args) {
     if (Helper.isString(fun)) {
-      console.assert(args.length === 0, 'Cannot evaluate a string with arguments');
+      assert(args.length === 0, 'Cannot evaluate a string with arguments');
       return /** @type {string} */ (fun);
     }
     return `(${fun})(${args.map(serializeArgument).join(',')})`;
@@ -78,7 +78,7 @@ class Helper {
    * @return {*}
    */
   static valueFromRemoteObject(remoteObject) {
-    console.assert(!remoteObject.objectId, 'Cannot extract value when objectId is given');
+    assert(!remoteObject.objectId, 'Cannot extract value when objectId is given');
     if (remoteObject.unserializableValue) {
       switch (remoteObject.unserializableValue) {
         case '-0':
@@ -242,7 +242,17 @@ class Helper {
   }
 }
 
+/**
+ * @param {*} value
+ * @param {string=} message
+ */
+function assert(value, message) {
+  if (!value)
+    throw new Error(message);
+}
+
 module.exports = {
   helper: Helper,
+  assert,
   debugError
 };

test/test.js

@@ -22,7 +22,7 @@ const GOLDEN_DIR = path.join(__dirname, 'golden');
 const OUTPUT_DIR = path.join(__dirname, 'output');
 const {TestRunner, Reporter, Matchers} = require('../utils/testrunner/');
 
-const {helper} = require('../lib/helper');
+const {helper, assert} = require('../lib/helper');
 if (process.env.COVERAGE)
   helper.recordPublicAPICoverage();
 
@@ -40,7 +40,7 @@ const extensionPath = path.resolve(__dirname, '../test/assets/simple-extension')
 if (executablePath)
   console.warn(`${YELLOW_COLOR}WARN: running tests with ${executablePath}${RESET_COLOR}`);
 // Make sure the `npm install` was run after the chromium roll.
-console.assert(fs.existsSync(puppeteer.executablePath()), `Chromium is not Downloaded. Run 'npm install' and try to re-run tests`);
+assert(fs.existsSync(puppeteer.executablePath()), `Chromium is not Downloaded. Run 'npm install' and try to re-run tests`);
 
 const slowMo = parseInt((process.env.SLOW_MO || '0').trim(), 10);
 const defaultBrowserOptions = {

utils/check_availability.js

@@ -15,6 +15,7 @@
  * limitations under the License.
  */
 
+const assert = require('assert');
 const puppeteer = require('..');
 const https = require('https');
 const SUPPORTER_PLATFORMS = ['linux', 'mac', 'win32', 'win64'];
@@ -40,7 +41,7 @@ class Table {
      * @param {!Array<string>} values
      */
   drawRow(values) {
-    console.assert(values.length === this.widths.length);
+    assert(values.length === this.widths.length);
     let row = '';
     for (let i = 0; i < values.length; ++i)
       row += padCenter(values[i], this.widths[i]);

utils/doclint/check_public_api/JSBuilder.js

@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+const assert = require('assert');
 const esprima = require('esprima');
 const ESTreeWalker = require('../../ESTreeWalker');
 const Documentation = require('./Documentation');
@@ -59,8 +60,8 @@ class JSOutline {
   }
 
   _onMethodDefinition(node) {
-    console.assert(this._currentClassName !== null);
+    assert(this._currentClassName !== null);
-    console.assert(node.value.type === 'FunctionExpression');
+    assert(node.value.type === 'FunctionExpression');
     const methodName = this._extractText(node.key);
     if (node.kind === 'get') {
       const property = Documentation.Member.createProperty(methodName);

utils/testrunner/Matchers.js

@@ -44,7 +44,8 @@ class Expect {
     function applyMatcher(matcherName, matcher, inverse, value, ...args) {
       const result = matcher.call(null, value, ...args);
       const message = `expect.${inverse ? 'not.' : ''}${matcherName} failed` + (result.message ? `: ${result.message}` : '');
-      console.assert(result.pass !== inverse, message);
+      if (result.pass === inverse)
+        throw new Error(message);
     }
   }
 }

utils/testrunner/TestRunner.js

@@ -316,7 +316,7 @@ class TestRunner extends EventEmitter {
   }
 
   _addHook(hookName, callback) {
-    console.assert(this._currentSuite[hookName] === null, `Only one ${hookName} hook available per suite`);
+    assert(this._currentSuite[hookName] === null, `Only one ${hookName} hook available per suite`);
     const hook = new UserCallback(callback, this._timeout);
     this._currentSuite[hookName] = hook;
   }
@@ -389,6 +389,15 @@ class TestRunner extends EventEmitter {
   }
 }
 
+/**
+ * @param {*} value
+ * @param {string=} message
+ */
+function assert(value, message) {
+  if (!value)
+    throw new Error(message);
+}
+
 TestRunner.Events = {
   Started: 'started',
   TestStarted: 'teststarted',