feat: send browsingContext.contextCreated event while subscribing (#…

…2255)

Subscribing to `browsingContext.contextCreated` should emit events for
the exiting contexts.

This required to add subscribe hooks to event manager. Hooks are engaged
when the subscription is done for the required method.

Spec:
https://w3c.github.io/webdriver-bidi/#ref-for-event-remote-end-subscribe-steps%E2%91%A1

Addressing WPT test
[**webdriver/tests/bidi/browsing_context/context_created/context_created.py:test_existing_context**](https://wpt.fyi/results/webdriver/tests/bidi/browsing_context/context_created/context_created.py?q=label%3Achromium-bidi-2023&run_id=6271852771278848&run_id=5105860015816704).

---------

Signed-off-by: Browser Automation Bot <browser-automation-bot@google.com>
Co-authored-by: Browser Automation Bot <browser-automation-bot@google.com>

src/bidiMapper/CommandProcessor.ts

@@ -92,7 +92,8 @@ export class CommandProcessor extends EventEmitter<CommandProcessorEventsMap> {
     this.#browserProcessor = new BrowserProcessor(browserCdpClient);
     this.#browsingContextProcessor = new BrowsingContextProcessor(
       browserCdpClient,
-      browsingContextStorage
+      browsingContextStorage,
+      eventManager
     );
     this.#cdpProcessor = new CdpProcessor(
       browsingContextStorage,

src/bidiMapper/modules/context/BrowsingContextProcessor.ts

@@ -19,26 +19,35 @@ import type {Protocol} from 'devtools-protocol';
 import type {CdpClient} from '../../../cdp/CdpClient.js';
 import {
   BrowsingContext,
+  ChromiumBidi,
   InvalidArgumentException,
   type EmptyResult,
   NoSuchUserContextException,
   NoSuchAlertException,
 } from '../../../protocol/protocol.js';
 import {CdpErrorConstants} from '../../../utils/CdpErrorConstants.js';
+import type {EventManager} from '../session/EventManager.js';
 
 import type {BrowsingContextImpl} from './BrowsingContextImpl.js';
 import type {BrowsingContextStorage} from './BrowsingContextStorage.js';
 
 export class BrowsingContextProcessor {
   readonly #browserCdpClient: CdpClient;
   readonly #browsingContextStorage: BrowsingContextStorage;
+  readonly #eventManager: EventManager;
 
   constructor(
     browserCdpClient: CdpClient,
-    browsingContextStorage: BrowsingContextStorage
+    browsingContextStorage: BrowsingContextStorage,
+    eventManager: EventManager
   ) {
     this.#browserCdpClient = browserCdpClient;
     this.#browsingContextStorage = browsingContextStorage;
+    this.#eventManager = eventManager;
+    this.#eventManager.addSubscribeHook(
+      ChromiumBidi.BrowsingContext.EventNames.ContextCreated,
+      this.#onContextCreatedSubscribeHook.bind(this)
+    );
   }
 
   getTree(
@@ -285,4 +294,25 @@ export class BrowsingContextProcessor {
     const context = this.#browsingContextStorage.getContext(params.context);
     return await context.locateNodes(params);
   }
+
+  #onContextCreatedSubscribeHook(
+    contextId: BrowsingContext.BrowsingContext
+  ): Promise<void> {
+    const context = this.#browsingContextStorage.getContext(contextId);
+    const contextsToReport = [
+      context,
+      ...this.#browsingContextStorage.getContext(contextId).allChildren,
+    ];
+    contextsToReport.forEach((context) => {
+      this.#eventManager.registerEvent(
+        {
+          type: 'event',
+          method: ChromiumBidi.BrowsingContext.EventNames.ContextCreated,
+          params: context.serializeToBidiValue(),
+        },
+        context.id
+      );
+    });
+    return Promise.resolve();
+  }
 }

src/bidiMapper/modules/session/EventManager.ts

@@ -22,6 +22,7 @@ import {
 } from '../../../protocol/protocol.js';
 import {Buffer} from '../../../utils/Buffer.js';
 import {DefaultMap} from '../../../utils/DefaultMap.js';
+import {distinctValues} from '../../../utils/DistinctValues.js';
 import {EventEmitter} from '../../../utils/EventEmitter.js';
 import {IdWrapper} from '../../../utils/IdWrapper.js';
 import type {Result} from '../../../utils/result.js';
@@ -74,6 +75,14 @@ const eventBufferLength: ReadonlyMap<ChromiumBidi.EventNames, number> = new Map(
   [[ChromiumBidi.Log.EventNames.LogEntryAdded, 100]]
 );
 
+/**
+ * Subscription item is a pair of event name and context id.
+ */
+export type SubscriptionItem = {
+  contextId: BrowsingContext.BrowsingContext;
+  event: ChromiumBidi.EventNames;
+};
+
 export class EventManager extends EventEmitter<EventManagerEventsMap> {
   /**
    * Maps event name to a set of contexts where this event already happened.
@@ -97,11 +106,19 @@ export class EventManager extends EventEmitter<EventManagerEventsMap> {
   #lastMessageSent = new Map<string, number>();
   #subscriptionManager: SubscriptionManager;
   #browsingContextStorage: BrowsingContextStorage;
+  /**
+   * Map of event name to hooks to be called when client is subscribed to the event.
+   */
+  #subscribeHooks: DefaultMap<
+    ChromiumBidi.EventNames,
+    ((contextId: BrowsingContext.BrowsingContext) => void)[]
+  >;
 
   constructor(browsingContextStorage: BrowsingContextStorage) {
     super();
     this.#browsingContextStorage = browsingContextStorage;
     this.#subscriptionManager = new SubscriptionManager(browsingContextStorage);
+    this.#subscribeHooks = new DefaultMap(() => []);
   }
 
   get subscriptionManager(): SubscriptionManager {
@@ -119,6 +136,13 @@ export class EventManager extends EventEmitter<EventManagerEventsMap> {
     return JSON.stringify({eventName, browsingContext, channel});
   }
 
+  addSubscribeHook(
+    event: ChromiumBidi.EventNames,
+    hook: (contextId: BrowsingContext.BrowsingContext) => Promise<void>
+  ): void {
+    this.#subscribeHooks.get(event).push(hook);
+  }
+
   registerEvent(
     event: ChromiumBidi.Event,
     contextId: BrowsingContext.BrowsingContext | null
@@ -172,9 +196,17 @@ export class EventManager extends EventEmitter<EventManagerEventsMap> {
       }
     }
 
+    // List of the subscription items that were actually added. Each contains a specific
+    // event and context. No domain event (like "network") or global context subscription
+    // (like null) are included.
+    const addedSubscriptionItems: SubscriptionItem[] = [];
+
     for (const eventName of eventNames) {
       for (const contextId of contextIds) {
-        this.#subscriptionManager.subscribe(eventName, contextId, channel);
+        addedSubscriptionItems.push(
+          ...this.#subscriptionManager.subscribe(eventName, contextId, channel)
+        );
+
         for (const eventWrapper of this.#getBufferedEvents(
           eventName,
           contextId,
@@ -193,6 +225,14 @@ export class EventManager extends EventEmitter<EventManagerEventsMap> {
       }
     }
 
+    // Iterate over all new subscription items and call hooks if any. There can be
+    // duplicates, e.g. when subscribing to the whole domain and some specific event in
+    // the same time ("network", "network.responseCompleted"). `distinctValues` guarantees
+    // that hooks are called only once per pair event + context.
+    distinctValues(addedSubscriptionItems).forEach(({contextId, event}) => {
+      this.#subscribeHooks.get(event).forEach((hook) => hook(contextId));
+    });
+
     await this.toggleModulesIfNeeded();
   }
 

src/bidiMapper/modules/session/SubscriptionManager.spec.ts

@@ -68,9 +68,48 @@ describe('SubscriptionManager', () => {
         return null;
       });
 
+    browsingContextStorage.getTopLevelContexts = sinon.stub().callsFake(() => {
+      return [{id: SOME_CONTEXT}, {id: ANOTHER_CONTEXT}];
+    });
+
     subscriptionManager = new SubscriptionManager(browsingContextStorage);
   });
 
+  describe('subscribe should return list of added subscriptions', () => {
+    describe('specific context', () => {
+      it('new subscription', () => {
+        expect(
+          subscriptionManager.subscribe(SOME_EVENT, SOME_CONTEXT, SOME_CHANNEL)
+        ).to.deep.equal([{event: SOME_EVENT, contextId: SOME_CONTEXT}]);
+      });
+
+      it('existing subscription', () => {
+        subscriptionManager.subscribe(SOME_EVENT, SOME_CONTEXT, SOME_CHANNEL);
+        expect(
+          subscriptionManager.subscribe(SOME_EVENT, SOME_CONTEXT, SOME_CHANNEL)
+        ).to.deep.equal([]);
+      });
+    });
+
+    describe('global', () => {
+      it('new subscription', () => {
+        expect(
+          subscriptionManager.subscribe(SOME_EVENT, null, SOME_CHANNEL)
+        ).to.deep.equal([
+          {event: SOME_EVENT, contextId: SOME_CONTEXT},
+          {event: SOME_EVENT, contextId: ANOTHER_CONTEXT},
+        ]);
+      });
+
+      it('existing subscription', () => {
+        subscriptionManager.subscribe(SOME_EVENT, SOME_CONTEXT, SOME_CHANNEL);
+        expect(
+          subscriptionManager.subscribe(SOME_EVENT, null, SOME_CHANNEL)
+        ).to.deep.equal([{event: SOME_EVENT, contextId: ANOTHER_CONTEXT}]);
+      });
+    });
+  });
+
   it('should subscribe twice to global and specific event in proper order', () => {
     subscriptionManager.subscribe(SOME_EVENT, null, SOME_CHANNEL);
     subscriptionManager.subscribe(SOME_EVENT, null, ANOTHER_CHANNEL);

src/bidiMapper/modules/session/SubscriptionManager.ts

@@ -17,12 +17,13 @@
 
 import type {BidiPlusChannel} from '../../../protocol/chromium-bidi.js';
 import {
+  type BrowsingContext,
   ChromiumBidi,
   InvalidArgumentException,
-  type BrowsingContext,
 } from '../../../protocol/protocol.js';
 import type {BrowsingContextStorage} from '../context/BrowsingContextStorage.js';
 
+import type {SubscriptionItem} from './EventManager.js';
 import {isCdpEvent} from './events.js';
 
 /**
@@ -204,36 +205,50 @@ export class SubscriptionManager {
     return false;
   }
 
+  /**
+   * Subscribes to event in the given context and channel.
+   * @param {EventNames} event
+   * @param {BrowsingContext.BrowsingContext | null} contextId
+   * @param {BidiPlusChannel} channel
+   * @return {SubscriptionItem[]} List of
+   * subscriptions. If the event is a whole module, it will return all the specific
+   * events. If the contextId is null, it will return all the top-level contexts which were
+   * not subscribed before the command.
+   */
   subscribe(
     event: ChromiumBidi.EventNames,
     contextId: BrowsingContext.BrowsingContext | null,
     channel: BidiPlusChannel
-  ): void {
+  ): SubscriptionItem[] {
     // All the subscriptions are handled on the top-level contexts.
     contextId = this.#browsingContextStorage.findTopLevelContextId(contextId);
 
     // Check if subscribed event is a whole module
     switch (event) {
       case ChromiumBidi.BiDiModule.BrowsingContext:
-        Object.values(ChromiumBidi.BrowsingContext.EventNames).map(
-          (specificEvent) => this.subscribe(specificEvent, contextId, channel)
-        );
-        return;
+        return Object.values(ChromiumBidi.BrowsingContext.EventNames)
+          .map((specificEvent) =>
+            this.subscribe(specificEvent, contextId, channel)
+          )
+          .flat();
       case ChromiumBidi.BiDiModule.Log:
-        Object.values(ChromiumBidi.Log.EventNames).map((specificEvent) =>
-          this.subscribe(specificEvent, contextId, channel)
-        );
-        return;
+        return Object.values(ChromiumBidi.Log.EventNames)
+          .map((specificEvent) =>
+            this.subscribe(specificEvent, contextId, channel)
+          )
+          .flat();
       case ChromiumBidi.BiDiModule.Network:
-        Object.values(ChromiumBidi.Network.EventNames).map((specificEvent) =>
-          this.subscribe(specificEvent, contextId, channel)
-        );
-        return;
+        return Object.values(ChromiumBidi.Network.EventNames)
+          .map((specificEvent) =>
+            this.subscribe(specificEvent, contextId, channel)
+          )
+          .flat();
       case ChromiumBidi.BiDiModule.Script:
-        Object.values(ChromiumBidi.Script.EventNames).map((specificEvent) =>
-          this.subscribe(specificEvent, contextId, channel)
-        );
-        return;
+        return Object.values(ChromiumBidi.Script.EventNames)
+          .map((specificEvent) =>
+            this.subscribe(specificEvent, contextId, channel)
+          )
+          .flat();
       default:
       // Intentionally left empty.
     }
@@ -248,12 +263,24 @@ export class SubscriptionManager {
     }
     const eventMap = contextToEventMap.get(contextId)!;
 
-    // Do not re-subscribe to events to keep the priority.
-    if (eventMap.has(event)) {
-      return;
+    const affectedContextIds = (
+      contextId === null
+        ? this.#browsingContextStorage.getTopLevelContexts().map((c) => c.id)
+        : [contextId]
+    )
+      // There can be contexts that are already subscribed to the event. Do not include
+      // them to the output.
+      .filter((contextId) => !this.isSubscribedTo(event, contextId));
+
+    if (!eventMap.has(event)) {
+      // Add subscription only if it's not already subscribed.
+      eventMap.set(event, this.#subscriptionPriority++);
     }
 
-    eventMap.set(event, this.#subscriptionPriority++);
+    return affectedContextIds.map((contextId) => ({
+      event,
+      contextId,
+    }));
   }
 
   /**