chore: Improve makeRequest test utility function (#7297)

## Explanation

The `makeRequest` utility function is now easier to control the return
type of using a type parameter, while still defaulting to the correct
type by default most of the time.

The previous version of this utility function frequently required a type
cast to prevent the return type from being resolved to `never`. It was
technically possible to specify the return type with a type parameter,
but it was onerous because the exact input type would also be required
as the first parameter.

This was done to simplify a later PR (#7296) that enables a lint rule
preventing unnecessary type assertions. The rule ended up breaking these
tests because the cast impacted how the type was inferred in a way that
the rule didn't predict.

## References

Relates to #7296

## Checklist

- [x] I've updated the test suite for new or updated code as appropriate
- [x] I've updated documentation (JSDoc, Markdown, etc.) for new or
updated code as appropriate
- [x] I've communicated my changes to consumers by [updating changelogs
for packages I've
changed](https://github.com/MetaMask/core/tree/main/docs/contributing.md#updating-changelogs)
- [ ] I've introduced [breaking
changes](https://github.com/MetaMask/core/tree/main/docs/breaking-changes.md)
in this PR and have prepared draft pull requests for clients and
consumer packages to resolve them

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Refactors the `makeRequest` test util to a simpler generic signature
and updates tests to use explicit generics and local type aliases
instead of casts.
> 
> - **Tests/Utils**:
> - **`makeRequest`**: Simplify to `<Request extends JsonRpcRequest =
JsonRpcRequest>(request: Partial<Request>) => Request`; remove dual
generics and `never`-prone casting.
> - **Tests**:
> - Replace casts with generic usage (e.g.,
`makeRequest<JsonRpcRequest>()`).
> - Introduce local alias `NumericIdRequest` and use
`makeRequest<NumericIdRequest>({...})` where needed.
> - Minor assertion updates to align with new typing (no runtime
behavior changes).
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
554f7d8. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: Gudahtt

packages/json-rpc-engine/src/v2/JsonRpcEngineV2.test.ts

@@ -72,7 +72,7 @@ describe('JsonRpcEngineV2', () => {
       // between these two cases:
       // - JsonRpcMiddleware<JsonRpcRequest> | JsonRpcMiddleware<JsonRpcNotification> (invalid)
       // - JsonRpcMiddleware<JsonRpcRequest> | JsonRpcMiddleware<JsonRpcCall> (valid)
-      expect(await engine.handle(makeRequest() as JsonRpcRequest)).toBe('foo');
+      expect(await engine.handle(makeRequest())).toBe('foo');
     });
   });
 
@@ -811,19 +811,20 @@ describe('JsonRpcEngineV2', () => {
 
       it('eagerly processes requests in parallel, i.e. without queueing them', async () => {
         const queue = makeArbitraryQueue(3);
-        const middleware: JsonRpcMiddleware<
-          JsonRpcRequest & { id: number }
-        > = async ({ request }) => {
+        type NumericIdRequest = JsonRpcRequest & { id: number };
+        const middleware: JsonRpcMiddleware<NumericIdRequest> = async ({
+          request,
+        }) => {
           await queue.enqueue(request.id);
           return null;
         };
         const engine = JsonRpcEngineV2.create({
           middleware: [middleware],
         });
 
-        const p0 = engine.handle(makeRequest({ id: 0 }));
-        const p1 = engine.handle(makeRequest({ id: 1 }));
-        const p2 = engine.handle(makeRequest({ id: 2 }));
+        const p0 = engine.handle(makeRequest<NumericIdRequest>({ id: 0 }));
+        const p1 = engine.handle(makeRequest<NumericIdRequest>({ id: 1 }));
+        const p2 = engine.handle(makeRequest<NumericIdRequest>({ id: 2 }));
 
         await queue.filled();
 
@@ -1210,7 +1211,7 @@ describe('JsonRpcEngineV2', () => {
         );
         await expect(
           // @ts-expect-error - Invalid at runtime and should cause a type error
-          engine.handle(makeRequest() as JsonRpcRequest),
+          engine.handle(makeRequest<JsonRpcRequest>()),
         ).rejects.toThrow(
           new JsonRpcEngineError(
             `Nothing ended request: ${stringify(makeRequest())}`,

packages/json-rpc-engine/tests/utils.ts

@@ -6,11 +6,8 @@ import type { JsonRpcNotification } from '../src/v2/utils';
 
 const jsonrpc = '2.0' as const;
 
-export const makeRequest = <
-  Input extends Partial<JsonRpcRequest>,
-  Output extends Input & JsonRpcRequest,
->(
-  request: Input = {} as Input,
+export const makeRequest = <Request extends JsonRpcRequest = JsonRpcRequest>(
+  request: Partial<Request> = {},
 ) =>
   ({
     jsonrpc,
@@ -19,7 +16,7 @@ export const makeRequest = <
 
     params: request.params === undefined ? [] : request.params,
     ...request,
-  }) as Output;
+  }) as Request;
 
 export const makeNotification = <Request extends Partial<JsonRpcRequest>>(
   params: Request = {} as Request,