diff --git a/src/common/Connection.ts b/src/common/Connection.ts
index 1e4b810a022b0..84312fa2ef073 100644
--- a/src/common/Connection.ts
+++ b/src/common/Connection.ts
@@ -56,7 +56,7 @@ export class Connection extends EventEmitter {
   #transport: ConnectionTransport;
   #delay: number;
   #lastId = 0;
-  #sessions: Map<string, CDPSession> = new Map();
+  #sessions: Map<string, CDPSessionImpl> = new Map();
   #closed = false;
   #callbacks: Map<number, ConnectionCallback> = new Map();
   #manuallyAttached = new Set<string>();
@@ -147,7 +147,7 @@ export class Connection extends EventEmitter {
     const object = JSON.parse(message);
     if (object.method === 'Target.attachedToTarget') {
       const sessionId = object.params.sessionId;
-      const session = new CDPSession(
+      const session = new CDPSessionImpl(
         this,
         object.params.targetInfo.type,
         sessionId
@@ -310,6 +310,47 @@ export const CDPSessionEmittedEvents = {
  * @public
  */
 export class CDPSession extends EventEmitter {
+  /**
+   * @internal
+   */
+  constructor() {
+    super();
+  }
+
+  connection(): Connection | undefined {
+    throw new Error('Not implemented');
+  }
+
+  send<T extends keyof ProtocolMapping.Commands>(
+    method: T,
+    ...paramArgs: ProtocolMapping.Commands[T]['paramsType']
+  ): Promise<ProtocolMapping.Commands[T]['returnType']>;
+  send<T extends keyof ProtocolMapping.Commands>(): Promise<
+    ProtocolMapping.Commands[T]['returnType']
+  > {
+    throw new Error('Not implemented');
+  }
+
+  /**
+   * Detaches the cdpSession from the target. Once detached, the cdpSession object
+   * won't emit any events and can't be used to send messages.
+   */
+  async detach(): Promise<void> {
+    throw new Error('Not implemented');
+  }
+
+  /**
+   * Returns the session's id.
+   */
+  id(): string {
+    throw new Error('Not implemented');
+  }
+}
+
+/**
+ * @internal
+ */
+export class CDPSessionImpl extends CDPSession {
   #sessionId: string;
   #targetType: string;
   #callbacks: Map<number, ConnectionCallback> = new Map();
@@ -325,11 +366,11 @@ export class CDPSession extends EventEmitter {
     this.#sessionId = sessionId;
   }
 
-  connection(): Connection | undefined {
+  override connection(): Connection | undefined {
     return this.#connection;
   }
 
-  send<T extends keyof ProtocolMapping.Commands>(
+  override send<T extends keyof ProtocolMapping.Commands>(
     method: T,
     ...paramArgs: ProtocolMapping.Commands[T]['paramsType']
   ): Promise<ProtocolMapping.Commands[T]['returnType']> {
@@ -386,7 +427,7 @@ export class CDPSession extends EventEmitter {
    * Detaches the cdpSession from the target. Once detached, the cdpSession object
    * won't emit any events and can't be used to send messages.
    */
-  async detach(): Promise<void> {
+  override async detach(): Promise<void> {
     if (!this.#connection) {
       throw new Error(
         `Session already detached. Most likely the ${
@@ -419,7 +460,7 @@ export class CDPSession extends EventEmitter {
   /**
    * Returns the session's id.
    */
-  id(): string {
+  override id(): string {
     return this.#sessionId;
   }
 }
diff --git a/src/common/NetworkManager.ts b/src/common/NetworkManager.ts
index da1a0d19f18b3..92deee72ccc57 100644
--- a/src/common/NetworkManager.ts
+++ b/src/common/NetworkManager.ts
@@ -15,7 +15,6 @@
  */
 
 import {Protocol} from 'devtools-protocol';
-import {ProtocolMapping} from 'devtools-protocol/types/protocol-mapping.js';
 import {assert} from '../util/assert.js';
 import {EventEmitter} from './EventEmitter.js';
 import {Frame} from './Frame.js';
@@ -25,6 +24,7 @@ import {FetchRequestId, NetworkEventManager} from './NetworkEventManager.js';
 import {debugError, isString} from './util.js';
 import {DeferredPromise} from '../util/DeferredPromise.js';
 import {createDebuggableDeferredPromise} from '../util/DebuggableDeferredPromise.js';
+import {CDPSession} from './Connection.js';
 
 /**
  * @public
@@ -66,13 +66,6 @@ export const NetworkManagerEmittedEvents = {
   RequestFinished: Symbol('NetworkManager.RequestFinished'),
 } as const;
 
-interface CDPSession extends EventEmitter {
-  send<T extends keyof ProtocolMapping.Commands>(
-    method: T,
-    ...paramArgs: ProtocolMapping.Commands[T]['paramsType']
-  ): Promise<ProtocolMapping.Commands[T]['returnType']>;
-}
-
 interface FrameManager {
   frame(frameId: string): Frame | null;
 }
diff --git a/test/src/NetworkManager.spec.ts b/test/src/NetworkManager.spec.ts
index 5602a5de65b5f..96e3a5f3e9ac2 100644
--- a/test/src/NetworkManager.spec.ts
+++ b/test/src/NetworkManager.spec.ts
@@ -26,6 +26,13 @@ import {HTTPResponse} from '../../lib/cjs/puppeteer/common/HTTPResponse.js';
 
 class MockCDPSession extends EventEmitter {
   async send(): Promise<any> {}
+  connection() {
+    return undefined;
+  }
+  async detach() {}
+  id() {
+    return '1';
+  }
 }
 
 describe('NetworkManager', () => {