Aki Salmi SoCraTes 2023 - Test Any Unit

coin-changer.spec.ts

import { assertEquals } from "https://deno.land/std@0.200.0/assert/mod.ts";
import {
  assertSpyCall,
  spy,
} from "https://deno.land/std@0.200.0/testing/mock.ts";

Deno.test("coin changer", () => {
  assertEquals(coinChanger(200), [200]);
});

Deno.test("coin changer with collaborator", () => {
  assertEquals(
    coinChanger(200, { availableCoins: () => [100, 100] }),
    [100, 100]
  );
});

Deno.test("account is called", () => {
  const notify = () => {};
  const notifyStub = spy({ notify }, "notify");
  coinChanger(200, { availableCoins: () => [100, 100] }, notifyStub);
  assertSpyCall(notifyStub, 0, {
    args: [200],
  });
});

export const coinChanger = (
  cents: number,
  { availableCoins }: { availableCoins: () => number[] } = {
    availableCoins: () => [200, 100, 50, 20, 10, 5],
  },
  notify?: (cents: number) => void
): number[] => {
  notify?.(cents);
  const result: number[] = [];
  for (const coin of availableCoins()) {
    while (cents >= coin) {
      result.push(coin);
      cents -= coin;
    }
  }
  return result;
};