true-myth/src/test-support.ts

A library for safe functional programming in JavaScript, with first-class support for TypeScript

/**
  Helpers to make it easier to test `Maybe` and `Result`.

  @module
 */

import Maybe, { type Just, isInstance as isMaybe } from './maybe.js';
import Result, { type Err, type Ok } from './result.js';

/**
  Unwrap the contained {@linkcode Just} value. Throws if `maybe` is {@linkcode
  "maybe".Nothing Nothing}.
 */
export function unwrap<T extends {}>(maybe: Maybe<T>): T;
/**
  Unwrap the contained {@linkcode Ok} value. Throws if `result` is an {@linkcode
  Err}.
 */
export function unwrap<T, E>(result: Result<T, E>): T;
export function unwrap(wrapped: Maybe<{}> | Result<unknown, unknown>): unknown {
  if (isMaybe(wrapped)) {
    return (wrapped as Just<{}>).value;
  } else {
    return (wrapped as Ok<unknown, unknown>).value;
  }
}

/**
  Unwrap the contained {@linkcode Err} error. Throws if `result` is {@linkcode
  Ok}.
 */
export function unwrapErr<E>(result: Result<unknown, E>): E {
  return (result as Err<unknown, E>).error;
}