[Feature]: Generics for APIRequestContext and APIResponse

[Ericlm]

🚀 Feature Request

It would be great to be able to directly type the response type of the provided APIResponse.json() instead of having an any type.

Already discussed in:
#13795

Example

interface User {
  id: string;
  name: string;
}

const response = await request.get<User>('/api/users/42');

// Directly typed as User 🥳
const user = await response.json()

Motivation

It would allow better type safety for requests made with Playwright, instead of using type cast.

[Skn0tt]

Could you elaborate on how this improves type safety compared to type casts? Either way the API can respond with payloads differen than the type, if you want proper type safety maybe you should check against a Zod schema instead.

[Ericlm]

You're right that this would not provide runtime validation, it wasn't what I meant.

A concrete use case is code generation from an OpenAPI specification. The
generator already knows the declared response type for each operation.

Today, if the generated client wants to preserve Playwright's raw
APIResponse — including its headers and body parsing —
it cannot carry the declared body type through Playwright's public types
without introducing its own wrapper or type cast:

// Generated from an OpenAPI specification
async function userById(): Promise<APIResponse> {
  return request.get('/users/42');
}

const response = await userById();
const user = await response.json(); // any

With a generic response type, the generated client could preserve that
compile-time contract:

async function userById(): Promise<APIResponse<User>> {
  return request.get<User>('/users/42');
}

const response = await userById();
const user = await response.json(); // User

[Skn0tt]

Discussed it with the team, we'll give it a try!