diff --git a/packages/playwright-core/src/client/channelOwner.ts b/packages/playwright-core/src/client/channelOwner.ts
index 163ff3ec0c..e3b541ee9a 100644
--- a/packages/playwright-core/src/client/channelOwner.ts
+++ b/packages/playwright-core/src/client/channelOwner.ts
@@ -141,6 +141,14 @@ export abstract class ChannelOwner<T extends channels.Channel = channels.Channel
     };
   }
 
+  private _validatorToWireContext(): ValidatorContext {
+    return {
+      tChannelImpl: tChannelImplToWire,
+      binary: this._connection.rawBuffers() ? 'buffer' : 'toBase64',
+      isUnderTest: () => this._platform.isUnderTest(),
+    };
+  }
+
   private _createChannel(base: Object): T {
     const channel = new Proxy(base, {
       get: (obj: any, prop: string | symbol) => {
@@ -149,7 +157,7 @@ export abstract class ChannelOwner<T extends channels.Channel = channels.Channel
           if (validator) {
             return async (params: any) => {
               return await this._wrapApiCall(async apiZone => {
-                const validatedParams = validator(params, '', { tChannelImpl: tChannelImplToWire, binary: this._connection.rawBuffers() ? 'buffer' : 'toBase64' });
+                const validatedParams = validator(params, '', this._validatorToWireContext());
                 if (!apiZone.isInternal && !apiZone.reported) {
                   // Reporting/tracing/logging this api call for the first time.
                   apiZone.params = params;
diff --git a/packages/playwright-core/src/client/clientBundle.ts b/packages/playwright-core/src/client/clientBundle.ts
index 28bfcf2af1..99df031213 100644
--- a/packages/playwright-core/src/client/clientBundle.ts
+++ b/packages/playwright-core/src/client/clientBundle.ts
@@ -16,12 +16,10 @@
 
 import { Connection } from './connection';
 import { setPlatformForSelectors } from './selectors';
-import { setIsUnderTestForValidator } from '../protocol/validatorPrimitives';
 
 import type { Platform } from './platform';
 
 export function createConnectionFactory(platform: Platform): () => Connection {
   setPlatformForSelectors(platform);
-  setIsUnderTestForValidator(() => platform.isUnderTest());
   return () => new Connection(platform);
 }
diff --git a/packages/playwright-core/src/client/connection.ts b/packages/playwright-core/src/client/connection.ts
index b123728a9b..1e83eb2af7 100644
--- a/packages/playwright-core/src/client/connection.ts
+++ b/packages/playwright-core/src/client/connection.ts
@@ -148,6 +148,14 @@ export class Connection extends EventEmitter {
     return await new Promise((resolve, reject) => this._callbacks.set(id, { resolve, reject, apiName, type, method }));
   }
 
+  private _validatorFromWireContext(): ValidatorContext {
+    return {
+      tChannelImpl: this._tChannelImplFromWire.bind(this),
+      binary: this._rawBuffers ? 'buffer' : 'fromBase64',
+      isUnderTest: () => this._platform.isUnderTest(),
+    };
+  }
+
   dispatch(message: object) {
     if (this._closedError)
       return;
@@ -166,7 +174,7 @@ export class Connection extends EventEmitter {
         callback.reject(parsedError);
       } else {
         const validator = findValidator(callback.type, callback.method, 'Result');
-        callback.resolve(validator(result, '', { tChannelImpl: this._tChannelImplFromWire.bind(this), binary: this._rawBuffers ? 'buffer' : 'fromBase64' }));
+        callback.resolve(validator(result, '', this._validatorFromWireContext()));
       }
       return;
     }
@@ -196,7 +204,7 @@ export class Connection extends EventEmitter {
     }
 
     const validator = findValidator(object._type, method, 'Event');
-    (object._channel as any).emit(method, validator(params, '', { tChannelImpl: this._tChannelImplFromWire.bind(this), binary: this._rawBuffers ? 'buffer' : 'fromBase64' }));
+    (object._channel as any).emit(method, validator(params, '', this._validatorFromWireContext()));
   }
 
   close(cause?: string) {
@@ -227,7 +235,7 @@ export class Connection extends EventEmitter {
       throw new Error(`Cannot find parent object ${parentGuid} to create ${guid}`);
     let result: ChannelOwner<any>;
     const validator = findValidator(type, '', 'Initializer');
-    initializer = validator(initializer, '', { tChannelImpl: this._tChannelImplFromWire.bind(this), binary: this._rawBuffers ? 'buffer' : 'fromBase64' });
+    initializer = validator(initializer, '', this._validatorFromWireContext());
     switch (type) {
       case 'Android':
         result = new Android(parent, type, guid, initializer);
diff --git a/packages/playwright-core/src/protocol/validatorPrimitives.ts b/packages/playwright-core/src/protocol/validatorPrimitives.ts
index 2c1a097da5..eadd2e014e 100644
--- a/packages/playwright-core/src/protocol/validatorPrimitives.ts
+++ b/packages/playwright-core/src/protocol/validatorPrimitives.ts
@@ -14,17 +14,12 @@
  * limitations under the License.
  */
 
-let isUnderTest = () => false;
-
-export function setIsUnderTestForValidator(getter: () => boolean) {
-  isUnderTest = getter;
-}
-
 export class ValidationError extends Error {}
 export type Validator = (arg: any, path: string, context: ValidatorContext) => any;
 export type ValidatorContext = {
-  tChannelImpl: (names: '*' | string[], arg: any, path: string, context: ValidatorContext) => any,
-  binary: 'toBase64' | 'fromBase64' | 'buffer',
+  tChannelImpl: (names: '*' | string[], arg: any, path: string, context: ValidatorContext) => any;
+  binary: 'toBase64' | 'fromBase64' | 'buffer';
+  isUnderTest: () => boolean;
 };
 export const scheme: { [key: string]: Validator } = {};
 
@@ -117,7 +112,7 @@ export const tObject = (s: { [key: string]: Validator }): Validator => {
       if (!Object.is(value, undefined))
         result[key] = value;
     }
-    if (isUnderTest()) {
+    if (context.isUnderTest()) {
       for (const [key, value] of Object.entries(arg)) {
         if (key.startsWith('__testHook'))
           result[key] = value;
diff --git a/packages/playwright-core/src/server/dispatchers/dispatcher.ts b/packages/playwright-core/src/server/dispatchers/dispatcher.ts
index c6eb6f7868..c96d18339d 100644
--- a/packages/playwright-core/src/server/dispatchers/dispatcher.ts
+++ b/packages/playwright-core/src/server/dispatchers/dispatcher.ts
@@ -200,13 +200,13 @@ export class DispatcherConnection {
 
   sendEvent(dispatcher: DispatcherScope, event: string, params: any) {
     const validator = findValidator(dispatcher._type, event, 'Event');
-    params = validator(params, '', { tChannelImpl: this._tChannelImplToWire.bind(this), binary: this._isLocal ? 'buffer' : 'toBase64' });
+    params = validator(params, '', this._validatorToWireContext());
     this.onmessage({ guid: dispatcher._guid, method: event, params });
   }
 
   sendCreate(parent: DispatcherScope, type: string, guid: string, initializer: any) {
     const validator = findValidator(type, '', 'Initializer');
-    initializer = validator(initializer, '', { tChannelImpl: this._tChannelImplToWire.bind(this), binary: this._isLocal ? 'buffer' : 'toBase64' });
+    initializer = validator(initializer, '', this._validatorToWireContext());
     this.onmessage({ guid: parent._guid, method: '__create__', params: { type, initializer, guid } });
   }
 
@@ -218,6 +218,22 @@ export class DispatcherConnection {
     this.onmessage({ guid: dispatcher._guid, method: '__dispose__', params: { reason } });
   }
 
+  private _validatorToWireContext(): ValidatorContext {
+    return {
+      tChannelImpl: this._tChannelImplToWire.bind(this),
+      binary: this._isLocal ? 'buffer' : 'toBase64',
+      isUnderTest,
+    };
+  }
+
+  private _validatorFromWireContext(): ValidatorContext {
+    return {
+      tChannelImpl: this._tChannelImplFromWire.bind(this),
+      binary: this._isLocal ? 'buffer' : 'fromBase64',
+      isUnderTest,
+    };
+  }
+
   private _tChannelImplFromWire(names: '*' | string[], arg: any, path: string, context: ValidatorContext): any {
     if (arg && typeof arg === 'object' && typeof arg.guid === 'string') {
       const guid = arg.guid;
@@ -279,8 +295,9 @@ export class DispatcherConnection {
     let validMetadata: channels.Metadata;
     try {
       const validator = findValidator(dispatcher._type, method, 'Params');
-      validParams = validator(params, '', { tChannelImpl: this._tChannelImplFromWire.bind(this), binary: this._isLocal ? 'buffer' : 'fromBase64' });
-      validMetadata = metadataValidator(metadata, '', { tChannelImpl: this._tChannelImplFromWire.bind(this), binary: this._isLocal ? 'buffer' : 'fromBase64' });
+      const validatorContext = this._validatorFromWireContext();
+      validParams = validator(params, '', validatorContext);
+      validMetadata = metadataValidator(metadata, '', validatorContext);
       if (typeof (dispatcher as any)[method] !== 'function')
         throw new Error(`Mismatching dispatcher: "${dispatcher._type}" does not implement "${method}"`);
     } catch (e) {
@@ -338,7 +355,7 @@ export class DispatcherConnection {
     try {
       const result = await dispatcher._handleCommand(callMetadata, method, validParams);
       const validator = findValidator(dispatcher._type, method, 'Result');
-      response.result = validator(result, '', { tChannelImpl: this._tChannelImplToWire.bind(this), binary: this._isLocal ? 'buffer' : 'toBase64' });
+      response.result = validator(result, '', this._validatorToWireContext());
       callMetadata.result = result;
     } catch (e) {
       if (isTargetClosedError(e) && sdkObject) {
diff --git a/packages/playwright-core/src/server/socksInterceptor.ts b/packages/playwright-core/src/server/socksInterceptor.ts
index 044c1d826a..c29981204f 100644
--- a/packages/playwright-core/src/server/socksInterceptor.ts
+++ b/packages/playwright-core/src/server/socksInterceptor.ts
@@ -18,6 +18,7 @@ import EventEmitter from 'events';
 
 import * as socks from './utils/socksProxy';
 import { ValidationError, findValidator } from '../protocol/validator';
+import { isUnderTest } from './utils/debug';
 
 import type { WebSocketTransport } from './transport';
 import type { ValidatorContext } from '../protocol/validator';
@@ -42,7 +43,7 @@ export class SocksInterceptor {
             const id = --lastId;
             this._ids.add(id);
             const validator = findValidator('SocksSupport', prop, 'Params');
-            params = validator(params, '', { tChannelImpl: tChannelForSocks, binary: 'toBase64' });
+            params = validator(params, '', { tChannelImpl: tChannelForSocks, binary: 'toBase64', isUnderTest });
             transport.send({ id, guid: this._socksSupportObjectGuid, method: prop, params, metadata: { stack: [], apiName: '', internal: true } } as any);
           } catch (e) {
           }
@@ -74,7 +75,7 @@ export class SocksInterceptor {
     }
     if (this._socksSupportObjectGuid && message.guid === this._socksSupportObjectGuid) {
       const validator = findValidator('SocksSupport', message.method, 'Event');
-      const params = validator(message.params, '', { tChannelImpl: tChannelForSocks, binary: 'fromBase64' });
+      const params = validator(message.params, '', { tChannelImpl: tChannelForSocks, binary: 'fromBase64', isUnderTest });
       this._channel.emit(message.method, params);
       return true;
     }