@halospv3/hce.shared-config/src/utils/Exact.ts

Automate commit message quality, changelogs, and CI/CD releases. Exports a semantic-release shareable configuration deserialized from this package's '.releaserc.yml'. Shared resources for .NET projects are also distributed with this package.

/**
 * ### `Exact<T, S>`
 *
 * [issue](https://github.com/microsoft/TypeScript/issues/12936#issuecomment-2816928183)\
 * [author](https://github.com/ahrjarrett)\
 * license: unlicensed[!]
 * @see
 * - {@link https://tsplay.dev/NnGG6m}
 */
export type Exact<T, S> = [keyof T] extends [keyof S]
  ? [T] extends [S] ? { [K in keyof T]: T[K] } : S
  : { [K in keyof T as K extends keyof S ? never : K]: TypeError<`Excess: '${Coerce<K>}'`> };

// eslint-disable-next-line jsdoc/require-jsdoc, @typescript-eslint/no-unused-vars
function exact<S, T extends Exact<T, S>>(x: S, _y: T): T {
  return x as unknown as T;
};

// should succeed
exact({ a: 1 }, { a: 1 });
exact({ a: 1, b: 'two' }, { a: 1, b: 'two' });

// should raise a TypeError
try {
  // @ts-expect-error Type 'boolean' is not assignable to type 'TypeError<"Excess: 'c'">'.ts(2322)
  exact({ a: 1 }, { a: 1, b: 'two', c: false });
}
catch { /* empty */ }
try {
  // @ts-expect-error Type 'number' is not assignable to type 'TypeError<"Excess: 'c'">'.ts(2322)
  exact({ a: 1, b: 2 }, { a: 1, b: 2, c: 3 });
}
catch { /* empty */ }
try {
  // @ts-expect-error Argument of type '{ a: number; }' is not assignable to parameter of type '{ a: number; b: number; }'. Property 'b' is missing in type '{ a: number; }' but required in type '{ a: number; b: number; }'.ts(2345)
  exact({ a: 1, b: 2 }, { a: 1 });
}
catch { /* empty */ }
interface TypeError<Message> { [' TypeError']: Message }
// prior art: use arktype's ^^^ leading whitespace trick to avoid collisions

type Coerce<T> = `${T & (string | number)}`;

try {
  // @ts-expect-error Should error
  exact({ a: 1 }, { a: 1, b: 2 });
  //                           ^ 🚫 raises a TypeError here
}
catch { /* empty */ }