00012-medium-chainable-options.ts

// ============= Test Cases =============
import type { Alike, Expect } from "./test-utils";

declare const a: Chainable;

const result1 = a
    .option("foo", 123)
    .option("bar", { value: "Hello World" })
    .option("name", "type-challenges")
    .get();

const result2 = a
    .option("name", "another name")
    // @ts-expect-error
    .option("name", "last name")
    .get();

const result3 = a
    .option("name", "another name")
    // @ts-expect-error
    .option("name", 123)
    .get();

type cases = [
    Expect<Alike<typeof result1, Expected1>>,
    Expect<Alike<typeof result2, Expected2>>,
    Expect<Alike<typeof result3, Expected3>>
];

type Expected1 = {
    foo: number;
    bar: {
        value: string;
    };
    name: string;
};

type Expected2 = {
    name: string;
};

type Expected3 = {
    name: number;
};

// ============= Your Code Here =============
type Chainable<T = {}> = {
    option: <K extends string, V>(
        key: K extends keyof T ? never : K,
        value: V
    ) => Chainable<Omit<T, K> & Record<K, V>>;

    get: () => T;
};