[Bug]: expect matchers from storybook/test ignores their generic parameter

[uhyo]

Describe the bug

I originally posted this here, but I decided to open a new issue for this.

In short, type definitions for some of the expect matchers from storybook/test are (still) not very good; according to the definition they are generic (accepts a type parameter), but actually the type parameter is meaningless.

Notably, this makes a deviation from vitest matchers which storybook/test's expect is based on.

import { expect as storybookExpect } from "storybook/test"; // [email protected]
import { expect as vitestExpect } from "vitest"; // [email protected]

interface FooObj {
  foo: number;
}

const barObj = {
  bar: "Hello",
};

storybookExpect(123).toMatchObject<FooObj>(barObj); // No error

vitestExpect(123).toMatchObject<FooObj>(barObj);
//                                      ^^^^^^ Error!
// Argument of type '{ bar: string; }' is not assignable to parameter of type 'FooObj'.
//   Property 'foo' is missing in type '{ bar: string; }' but required in type 'FooObj'.

Reproduction link

https://www.typescriptlang.org/play/?#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

Reproduction steps

1. Open the TypeScript Playground link above.
2. Wait for a while.
3. See a type error.

System

Storybook Environment Info:

  System:
    OS: Linux 5.15 Ubuntu 22.04.1 LTS 22.04.1 LTS (Jammy Jellyfish)
    CPU: (16) x64 AMD Ryzen 7 PRO 6850U with Radeon Graphics
    Shell: 5.1.16 - /bin/bash
  Binaries:
    Node: 22.14.0 - ~/.volta/tools/image/node/22.14.0/bin/node
    Yarn: 4.1.1 - ~/.volta/tools/image/yarn/4.1.1/bin/yarn
    npm: 10.9.2 - ~/.volta/tools/image/node/22.14.0/bin/npm <----- active
    pnpm: 8.15.8 - ~/.volta/bin/pnpm
  npmPackages:
    storybook: ^9.0.0-rc.4 => 9.0.0-rc.4

Additional context

I believe the fix in #31395 wasn't perfect. The fix does preserve type parameters from generic matchers, but the function signatures are still broken after Promisify.

[greptile-apps]

** Disclaimer** This information might be inaccurate, due to it being generated automatically
This appears to be related to the type definitions in @storybook/test package. The issue is in how generic type parameters are handled after the Promisify transformation. Key files to modify: 1. code/lib/test/src/index.ts - Update matcher type definitions 2. code/lib/test/src/types.ts - Fix generic parameter handling Proposed fix: typescript // In types.ts, update the Promisify type to preserve generic parameters: type Promisify<T> = T extends (...args: infer A) => infer R ? (...args: A) => Promise<Awaited<R>> : T extends { [K in keyof T]: (...args: any[]) => any } ? { [K in keyof T]: Promisify<T[K]> } : T; // Update matcher definitions to properly handle generics: interface Matchers<R, T = unknown> { toMatchObject<E extends object>(expected: E): R; // Add other matchers similarly } This should preserve type checking behavior similar to Vitest's implementation.

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