chore: simplify slowmo implementation (#18990)

packages/playwright-core/src/protocol/debug.ts

@@ -23,6 +23,7 @@ export const commandsWithTracingSnapshots = new Set([
   'WebSocket.waitForEventInfo',
   'ElectronApplication.waitForEventInfo',
   'AndroidDevice.waitForEventInfo',
+  'Page.emulateMedia',
   'Page.goBack',
   'Page.goForward',
   'Page.reload',
@@ -90,6 +91,7 @@ export const commandsWithTracingSnapshots = new Set([
   'ElementHandle.dblclick',
   'ElementHandle.dispatchEvent',
   'ElementHandle.fill',
+  'ElementHandle.focus',
   'ElementHandle.hover',
   'ElementHandle.innerHTML',
   'ElementHandle.innerText',

packages/playwright-core/src/server/browser.ts

@@ -62,6 +62,7 @@ export type BrowserOptions = PlaywrightOptions & {
 };
 
 export abstract class Browser extends SdkObject {
+
   static Events = {
     Disconnected: 'disconnected',
   };

packages/playwright-core/src/server/browserContext.ts

@@ -76,6 +76,7 @@ export abstract class BrowserContext extends SdkObject {
   private _settingStorageState = false;
   readonly initScripts: string[] = [];
   private _routesInFlight = new Set<network.Route>();
+  private _debugger!: Debugger;
 
   constructor(browser: Browser, options: channels.BrowserNewContextParams, browserContextId: string | undefined) {
     super(browser, 'browser-context');
@@ -112,16 +113,16 @@ export abstract class BrowserContext extends SdkObject {
     if (this.attribution.isInternalPlaywright)
       return;
     // Debugger will pause execution upon page.pause in headed mode.
-    const contextDebugger = new Debugger(this);
+    this._debugger = new Debugger(this);
 
     // When PWDEBUG=1, show inspector for each context.
     if (debugMode() === 'inspector')
       await Recorder.show(this, { pauseOnNextStatement: true });
 
     // When paused, show inspector.
-    if (contextDebugger.isPaused())
+    if (this._debugger.isPaused())
       Recorder.showInspector(this);
-    contextDebugger.on(Debugger.Events.PausedStateChanged, () => {
+    this._debugger.on(Debugger.Events.PausedStateChanged, () => {
       Recorder.showInspector(this);
     });
 
@@ -134,6 +135,10 @@ export abstract class BrowserContext extends SdkObject {
       await this.grantPermissions(this._options.permissions);
   }
 
+  debugger(): Debugger {
+    return this._debugger;
+  }
+
   async _ensureVideosPath() {
     if (this._options.recordVideo)
       await mkdirIfNeeded(path.join(this._options.recordVideo.dir, 'dummy'));

packages/playwright-core/src/server/debugger.ts

@@ -32,6 +32,7 @@ export class Debugger extends EventEmitter implements InstrumentationListener {
     PausedStateChanged: 'pausedstatechanged'
   };
   private _muted = false;
+  private _slowMo: number | undefined;
 
   constructor(context: BrowserContext) {
     super();
@@ -44,12 +45,7 @@ export class Debugger extends EventEmitter implements InstrumentationListener {
     this._context.once(BrowserContext.Events.Close, () => {
       this._context.instrumentation.removeListener(this);
     });
-  }
+    this._slowMo = this._context._browser.options.slowMo;
-
-  static lookup(context?: BrowserContext): Debugger | undefined {
-    if (!context)
-      return;
-    return (context as any)[symbol] as Debugger | undefined;
   }
 
   async setMuted(muted: boolean) {
@@ -63,6 +59,15 @@ export class Debugger extends EventEmitter implements InstrumentationListener {
       await this.pause(sdkObject, metadata);
   }
 
+  async _doSlowMo() {
+    await new Promise(f => setTimeout(f, this._slowMo));
+  }
+
+  async onAfterCall(sdkObject: SdkObject, metadata: CallMetadata): Promise<void> {
+    if (this._slowMo && shouldSlowMo(metadata))
+      await this._doSlowMo();
+  }
+
   async onBeforeInputAction(sdkObject: SdkObject, metadata: CallMetadata): Promise<void> {
     if (this._muted)
       return;
@@ -134,3 +139,7 @@ function shouldPauseBeforeStep(metadata: CallMetadata): boolean {
   // since we stop in them on a separate instrumentation signal.
   return commandsWithTracingSnapshots.has(step) && !pausesBeforeInputActions.has(metadata.type + '.' + metadata.method);
 }
+
+export function shouldSlowMo(metadata: CallMetadata): boolean {
+  return commandsWithTracingSnapshots.has(metadata.type + '.' + metadata.method);
+}

packages/playwright-core/src/server/dom.ts

@@ -117,10 +117,6 @@ export class FrameExecutionContext extends js.ExecutionContext {
     }
     return this._injectedScriptPromise;
   }
-
-  override async doSlowMo() {
-    return this.frame._page._doSlowMo();
-  }
 }
 
 export class ElementHandle<T extends Node = Node> extends js.JSHandle<T> {
@@ -255,7 +251,6 @@ export class ElementHandle<T extends Node = Node> extends js.JSHandle<T> {
     await this._page._frameManager.waitForSignalsCreatedBy(null, false /* noWaitFor */, async () => {
       return main.evaluate(([injected, node, { type, eventInit }]) => injected.dispatchEvent(node, type, eventInit), [await main.injectedScript(), this, { type, eventInit }] as const);
     });
-    await this._page._doSlowMo();
   }
 
   async _scrollRectIntoViewIfNeeded(rect?: types.Rect): Promise<'error:notvisible' | 'error:notconnected' | 'done'> {
@@ -559,7 +554,6 @@ export class ElementHandle<T extends Node = Node> extends js.JSHandle<T> {
       const result = await this.evaluatePoll(progress, ([injected, node, { optionsToSelect, force }]) => {
         return injected.waitForElementStatesAndPerformAction(node, ['visible', 'enabled'], force, injected.selectOptions.bind(injected, optionsToSelect));
       }, { optionsToSelect, force: options.force });
-      await this._page._doSlowMo();
       return result;
     });
   }
@@ -651,7 +645,6 @@ export class ElementHandle<T extends Node = Node> extends js.JSHandle<T> {
       else
         await this._page._delegate.setInputFiles(retargeted, filePayloads!);
     });
-    await this._page._doSlowMo();
     return 'done';
   }
 
@@ -659,7 +652,6 @@ export class ElementHandle<T extends Node = Node> extends js.JSHandle<T> {
     const controller = new ProgressController(metadata, this);
     await controller.run(async progress => {
       const result = await this._focus(progress);
-      await this._page._doSlowMo();
       return assertDone(throwRetargetableDOMError(result));
     }, 0);
   }

packages/playwright-core/src/server/frames.ts

@@ -705,7 +705,6 @@ export class Frame extends SdkObject {
 
     const request = event.newDocument ? event.newDocument.request : undefined;
     const response = request ? request._finalRequest().response() : null;
-    await this._page._doSlowMo();
     return response;
   }
 
@@ -765,24 +764,18 @@ export class Frame extends SdkObject {
   async evaluateExpressionHandleAndWaitForSignals(expression: string, isFunction: boolean | undefined, arg: any, world: types.World = 'main'): Promise<any> {
     const context = await this._context(world);
     const handle = await context.evaluateExpressionHandleAndWaitForSignals(expression, isFunction, arg);
-    if (world === 'main')
-      await this._page._doSlowMo();
     return handle;
   }
 
   async evaluateExpression(expression: string, isFunction: boolean | undefined, arg: any, world: types.World = 'main'): Promise<any> {
     const context = await this._context(world);
     const value = await context.evaluateExpression(expression, isFunction, arg);
-    if (world === 'main')
-      await this._page._doSlowMo();
     return value;
   }
 
   async evaluateExpressionAndWaitForSignals(expression: string, isFunction: boolean | undefined, arg: any, world: types.World = 'main'): Promise<any> {
     const context = await this._context(world);
     const value = await context.evaluateExpressionAndWaitForSignals(expression, isFunction, arg);
-    if (world === 'main')
-      await this._page._doSlowMo();
     return value;
   }
 
@@ -833,7 +826,6 @@ export class Frame extends SdkObject {
     await this._scheduleRerunnableTask(metadata, selector, (progress, element, data) => {
       progress.injectedScript.dispatchEvent(element, data.type, data.eventInit);
     }, { type, eventInit }, { mainWorld: true, ...options });
-    await this._page._doSlowMo();
   }
 
   async evalOnSelectorAndWaitForSignals(selector: string, strict: boolean, expression: string, isFunction: boolean | undefined, arg: any): Promise<any> {
@@ -919,7 +911,6 @@ export class Frame extends SdkObject {
           document.close();
         }, { html, tag });
         await Promise.all([contentPromise, lifecyclePromise]);
-        await this._page._doSlowMo();
         return null;
       });
     }, this._page._timeoutSettings.navigationTimeout(options));
@@ -1195,7 +1186,6 @@ export class Frame extends SdkObject {
     const controller = new ProgressController(metadata, this);
     await controller.run(async progress => {
       dom.assertDone(await this._retryWithProgressIfNotConnected(progress, selector, options.strict, handle => handle._focus(progress)));
-      await this._page._doSlowMo();
     }, this._page._timeoutSettings.timeout(options));
   }
 
@@ -1203,7 +1193,6 @@ export class Frame extends SdkObject {
     const controller = new ProgressController(metadata, this);
     await controller.run(async progress => {
       dom.assertDone(await this._retryWithProgressIfNotConnected(progress, selector, options.strict, handle => handle._blur(progress)));
-      await this._page._doSlowMo();
     }, this._page._timeoutSettings.timeout(options));
   }
 

packages/playwright-core/src/server/input.ts

@@ -58,7 +58,6 @@ export class Keyboard {
       this._pressedModifiers.add(description.key as types.KeyboardModifier);
     const text = description.text;
     await this._raw.keydown(this._pressedModifiers, description.code, description.keyCode, description.keyCodeWithoutLocation, description.key, description.location, autoRepeat, text);
-    await this._page._doSlowMo();
   }
 
   private _keyDescriptionForString(keyString: string): KeyDescription {
@@ -79,12 +78,10 @@ export class Keyboard {
       this._pressedModifiers.delete(description.key as types.KeyboardModifier);
     this._pressedKeys.delete(description.code);
     await this._raw.keyup(this._pressedModifiers, description.code, description.keyCode, description.keyCodeWithoutLocation, description.key, description.location);
-    await this._page._doSlowMo();
   }
 
   async insertText(text: string) {
     await this._raw.sendText(text);
-    await this._page._doSlowMo();
   }
 
   async type(text: string, options?: { delay?: number }) {
@@ -188,7 +185,6 @@ export class Mouse {
       const middleX = fromX + (x - fromX) * (i / steps);
       const middleY = fromY + (y - fromY) * (i / steps);
       await this._raw.move(middleX, middleY, this._lastButton, this._buttons, this._keyboard._modifiers(), !!options.forClick);
-      await this._page._doSlowMo();
     }
   }
 
@@ -197,7 +193,6 @@ export class Mouse {
     this._lastButton = button;
     this._buttons.add(button);
     await this._raw.down(this._x, this._y, this._lastButton, this._buttons, this._keyboard._modifiers(), clickCount);
-    await this._page._doSlowMo();
   }
 
   async up(options: { button?: types.MouseButton, clickCount?: number } = {}) {
@@ -205,7 +200,6 @@ export class Mouse {
     this._lastButton = 'none';
     this._buttons.delete(button);
     await this._raw.up(this._x, this._y, button, this._buttons, this._keyboard._modifiers(), clickCount);
-    await this._page._doSlowMo();
   }
 
   async click(x: number, y: number, options: { delay?: number, button?: types.MouseButton, clickCount?: number } = {}) {
@@ -236,7 +230,6 @@ export class Mouse {
 
   async wheel(deltaX: number, deltaY: number) {
     await this._raw.wheel(this._x, this._y, this._buttons, this._keyboard._modifiers(), deltaX, deltaY);
-    await this._page._doSlowMo();
   }
 }
 
@@ -317,6 +310,5 @@ export class Touchscreen {
     if (!this._page._browserContext._options.hasTouch)
       throw new Error('hasTouch must be enabled on the browser context before using the touchscreen.');
     await this._raw.tap(x, y, this._page.keyboard._modifiers());
-    await this._page._doSlowMo();
   }
 }

packages/playwright-core/src/server/page.ts

@@ -253,13 +253,6 @@ export class Page extends SdkObject {
     ]);
   }
 
-  async _doSlowMo() {
-    const slowMo = this._browserContext._browser.options.slowMo;
-    if (!slowMo)
-      return;
-    await new Promise(x => setTimeout(x, slowMo));
-  }
-
   _didClose() {
     this._frameManager.dispose();
     this._frameThrottler.dispose();
@@ -378,7 +371,6 @@ export class Page extends SdkObject {
         this.mainFrame()._waitForNavigation(progress, true /* requiresNewDocument */, options),
         this._delegate.reload(),
       ]);
-      await this._doSlowMo();
       return response;
     }), this._timeoutSettings.navigationTimeout(options));
   }
@@ -399,7 +391,6 @@ export class Page extends SdkObject {
       const response = await waitPromise;
       if (error)
         throw error;
-      await this._doSlowMo();
       return response;
     }), this._timeoutSettings.navigationTimeout(options));
   }
@@ -420,7 +411,6 @@ export class Page extends SdkObject {
       const response = await waitPromise;
       if (error)
         throw error;
-      await this._doSlowMo();
       return response;
     }), this._timeoutSettings.navigationTimeout(options));
   }
@@ -436,7 +426,6 @@ export class Page extends SdkObject {
       this._emulatedMedia.forcedColors = options.forcedColors;
 
     await this._delegate.updateEmulateMedia();
-    await this._doSlowMo();
   }
 
   emulatedMedia(): EmulatedMedia {
@@ -452,7 +441,6 @@ export class Page extends SdkObject {
   async setViewportSize(viewportSize: types.Size) {
     this._emulatedSize = { viewport: { ...viewportSize }, screen: { ...viewportSize } };
     await this._delegate.updateEmulatedViewportSize();
-    await this._doSlowMo();
   }
 
   viewportSize(): types.Size | null {

packages/playwright-core/src/server/recorder.ts

@@ -86,7 +86,7 @@ export class Recorder implements InstrumentationListener {
     this._contextRecorder = new ContextRecorder(context, params);
     this._context = context;
     this._omitCallTracking = !!params.omitCallTracking;
-    this._debugger = Debugger.lookup(context)!;
+    this._debugger = context.debugger();
     this._handleSIGINT = params.handleSIGINT;
     context.instrumentation.addListener(this, context);
     this._currentLanguage = this._contextRecorder.languageName();

packages/protocol/src/protocol.yml

@@ -1218,6 +1218,8 @@ Page:
           - active
           - none
           - no-override
+      tracing:
+        snapshot: true
 
     exposeBinding:
       parameters:
@@ -2365,6 +2367,8 @@ ElementHandle:
         pausesBeforeInput: true
 
     focus:
+      tracing:
+        snapshot: true
 
     getAttribute:
       parameters:

tests/library/slowmo.spec.ts

@@ -19,13 +19,15 @@ import { attachFrame } from '../config/utils';
 
 async function checkSlowMo(toImpl, page, task) {
   let didSlowMo = false;
-  const orig = toImpl(page)._doSlowMo;
+  const contextDebugger = toImpl(page.context()).debugger();
-  toImpl(page)._doSlowMo = async function(...args) {
+  contextDebugger._slowMo = 100;
+  const orig = contextDebugger._doSlowMo;
+  contextDebugger._doSlowMo = async () => {
     if (didSlowMo)
       throw new Error('already did slowmo');
     await new Promise(x => setTimeout(x, 100));
     didSlowMo = true;
-    return orig.call(this, ...args);
+    return orig.call(contextDebugger);
   };
   await task();
   expect(!!didSlowMo).toBe(true);