satisfies operator breaks with callback on Partial object literals

[JDMathew]

🔎 Search Terms

"satisfies", "callback", "function"

🕗 Version & Regression Information

• This is the behavior in every version I tried (above 4.8), and I reviewed the FAQ for entries about "Bugs that Aren't Bugs"

⏯ Playground Link

Link to playground

💻 Code

type AuthState = {
  isLoading: boolean;
  isLoggedIn: boolean;
  userToken: string | null;
};

type ActionFunction = (arg: any) => {
  type: string;
  payload: Prettify<Partial<AuthState>>;
};

export const authActions = {
  signOut: () => ({
    type: actionTypes.SIGN_OUT,
    payload: { userToken: null, isLoggedIn: false },
  }),
  login: ({ userToken }: { userToken: string }) => ({
    type: actionTypes.LOGIN,
    payload: { userToken, isLoggedIn: true },
  }),
  restoreToken: ({ userToken }: { userToken: string }) => ({
    type: 22, // error on type for 22: Type 'number' is not assignable to type 'string'.
    payload: { userToken, isLoading: false, notAValidKey: 'Value' }, // no error on notAValidKey, should error Object literal may only specify known properties, and 'notAValidKey' does not exist in type 'Partial<AuthState>'
  }),
} satisfies Record<string, ActionFunction>;

🙁 Actual behavior

There is no error thrown on payload for the key notAValidKey as one would expect since this key isn't inside the Partial type AuthState. There is an error thrown for type with value 22 so the callback type ActionFunction isn't breaking the satisfies operator.

🙂 Expected behavior

This should throw an error on restoreToken in the above authActions const.
The behaviour should mimic what happens when there is no callback in the object. For example as it errors here:

type AuthState = {
  isLoading: boolean;
  isLoggedIn: boolean;
  userToken: string | null;
};


export const action = {
  key: {
    isLoggedIn: true,
    notAValidKey: 'Value', // error thrown: Object literal may only specify known properties, and 'notAValidKey' does not exist in type 'Partial<AuthState>'.
  },
} satisfies Record<string, Partial<AuthState>>;

Additional information about the issue

No response

[fatcerberus]

Functions aren’t contextually typed in their return type afaik so EPC doesn’t apply. Note that the excess property check is more of a built-in lint rule than a type check, so it’s intentionally not comprehensive.

[fatcerberus]

Simplified repro (Playground):

type AuthState = {
  isLoading: boolean;
  isLoggedIn: boolean;
  userToken: string | null;
};

type ActionFunction = (arg: any) => {
  type: string;
  payload: Partial<AuthState>;
};

const action1 = (({ userToken }: { userToken: string }) => ({
  type: "fun",
  payload: { userToken, isLoading: false, notAValidKey: 'Value' },
})) satisfies ActionFunction;  // no EPC error

const action2: ActionFunction = ({ userToken }: { userToken: string }) => ({
  type: "fun",
  payload: { userToken, isLoading: false, notAValidKey: 'Value' },
});  // also no EPC error

which I'm almost positive is a duplicate of like 10 other issues (latest I can find: #54661). tl;dr you shouldn't rely on the excess property check to enforce runtime invariants - you need #12936 for that.

[fatcerberus]

The closest thing to a canonical duplicate afaict is #7547

[RyanCavanaugh]

#241 is also relevant

[typescript-bot]

This issue has been marked as "Not a Defect" and has seen no recent activity. It has been automatically closed for house-keeping purposes.