Properly type ngOnSetup method return

[crutchcorn]

I would love for the ngOnSetup function to enforce the return type of the setup function.

While I would love for the typings to be as simple as:

  ngOnSetup(props: this): Partial<Record<keyof this, any>>

I seem to get errors while doing so:

TS2322: Type '{ test: Ref ; addToPlus: () => void; }' is not assignable to type 'Partial  >'.

What's interesting about this error in particular is that Partial is not a primitive type, but rather a utility type. This makes me think there is a bug in TypeScript

---

Playing around with the typings, I managed to get this working on the consuming side of things:

  ngOnSetup(props: this): Partial<Record<keyof InstanceType<typeof AppComponent>, any>> {
    const test = ref(12);

    const addToPlus = (): void => {
      test.value += 1;
    };

    return {
      test,
      addToPlus
    };
  }

However, while trying to extract this logic out to a sensible version in the library itself, I saw errors. The following is the closest approximation to the types that I wanted to see:

// lib/Setup.ts
export type SetupReturn<T extends new (...args: any) => any> = Partial<Record<keyof T, any>>;

export declare interface OnSetup {
  ngOnSetup<T>(props: this): SetupReturn<T extends new (...args: any) => any>;
}

// app/app.component.ts

ngOnSetup(props: this): SetupReturn<InstanceType<typeof AppComponent>> {
  const test = ref(12);

  const addToPlus = (): void => {
    test.value += 1;
  };

  return {
    test,
    addToPlus
  };
}

However, this code doesn't work either. I get the following error:

TS2416: Property 'ngOnSetup' in type 'AppComponent' is not assignable to the same property in base type 'OnSetup'.   Type '(props: this) => Partial<Record<"prototype", any>>' is not assignable to type '<T>(props: this) => Partial<Record<keyof (T extends new (...args: any) => any ? any : any), any>>'.     Type 'Partial<Record<"prototype", any>>' is not assignable to type 'Partial<Record<keyof (T extends new (...args: any) => any ? any : any), any>>'