bird-watcher.spec.js

import { totalBirdCount, birdsInWeek, fixBirdCountLog } from './bird-watcher';

describe('totalBirdCount', () => {
  test('calculates the correct total number of birds', () => {
    const birdsPerDay = [9, 0, 8, 4, 5, 1, 3];
    expect(totalBirdCount(birdsPerDay)).toBe(30);
  });

  test('works for a short bird count list', () => {
    const birdsPerDay = [2];
    expect(totalBirdCount(birdsPerDay)).toBe(2);
  });

  test('works for a long bird count list', () => {
    // prettier-ignore
    const birdsPerDay = [2, 8, 4, 1, 3, 5, 0, 4, 1, 6, 0, 3, 0, 1, 5, 4, 1, 1, 2, 6];
    expect(totalBirdCount(birdsPerDay)).toBe(57);
  });
});

describe('birdsInWeek', () => {
  test('calculates the number of birds in the first week', () => {
    const birdsPerDay = [3, 0, 5, 1, 0, 4, 1, 0, 3, 4, 3, 0, 8, 0];
    expect(birdsInWeek(birdsPerDay, 1)).toBe(14);
  });

  test('calculates the number of birds for a week in the middle of the log', () => {
    // prettier-ignore
    const birdsPerDay = [4, 7, 3, 2, 1, 1, 2, 0, 2, 3, 2, 7, 1, 3, 0, 6, 5, 3, 7, 2, 3];
    expect(birdsInWeek(birdsPerDay, 2)).toBe(18);
  });

  test('works when there is only one week', () => {
    const birdsPerDay = [3, 0, 3, 3, 2, 1, 0];
    expect(birdsInWeek(birdsPerDay, 1)).toBe(12);
  });

  test('works for a long bird count list', () => {
    const week21 = [2, 0, 1, 4, 1, 3, 0];
    const birdsPerDay = randomArray(20 * 7)
      .concat(week21)
      .concat(randomArray(10 * 7));

    expect(birdsInWeek(birdsPerDay, 21)).toBe(11);
  });
});

describe('fixBirdCountLog', () => {
  test('returns a bird count list with the corrected values', () => {
    const birdsPerDay = [3, 0, 5, 1, 0, 4, 1, 0, 3, 4, 3, 0];
    const expected = [4, 0, 6, 1, 1, 4, 2, 0, 4, 4, 4, 0];
    expect(fixBirdCountLog(birdsPerDay)).toEqual(expected);
  });

  test('does not create a new array', () => {
    const birdsPerDay = [2, 0, 1, 4, 1, 3, 0];

    // This checks that the same object that was passed in is returned.
    // https://jestjs.io/docs/expect#tobevalue
    expect(Object.is(fixBirdCountLog(birdsPerDay), birdsPerDay)).toBe(true);
  });

  test('works for a short bird count list', () => {
    expect(fixBirdCountLog([4, 2])).toEqual([5, 2]);
  });

  test('works for a long bird count list', () => {
    // prettier-ignore
    const birdsPerDay = [2, 8, 4, 1, 3, 5, 0, 4, 1, 6, 0, 3, 0, 1, 5, 4, 1, 1, 2, 6];
    // prettier-ignore
    const expected = [3, 8, 5, 1, 4, 5, 1, 4, 2, 6, 1, 3, 1, 1, 6, 4, 2, 1, 3, 6];
    expect(fixBirdCountLog(birdsPerDay)).toEqual(expected);
  });
});

function randomArray(length) {
  return Array.from({ length: length }, () => Math.floor(Math.random() * 8));
}