comparators.test.ts

import {
  byBoolean,
  byCodeUnit,
  byDate,
  byNumber,
  byString,
  byStringWithoutCaseSensitivity,
} from './comparators';

describe('byNumber', () => {
  it('compares by numeric value', () => {
    expect(byNumber(5, 9000)).toBeLessThan(0);
    expect(byNumber(9000, 5)).toBeGreaterThan(0);
  });

  it('defines equality', () => {
    expect(byNumber(42, 42)).toBe(0);
  });

  it('sorts numbers correctly', () => {
    const result = [1, 3, 5, 2, 4].sort(byNumber);

    expect(result).toEqual([1, 2, 3, 4, 5]);
  });
});

describe('byString', () => {
  it('compares by lexicographic order', () => {
    expect(byString('a', 'b')).toBeLessThan(0);
    expect(byString('b', 'a')).toBeGreaterThan(0);
  });

  it('defines equality', () => {
    expect(byString('foobar', 'foobar')).toBe(0);
  });

  it('sorts strings correctly', () => {
    const input = ['B', 'b', 'A', 'a'];
    const expected = [...input].sort((a, b) => a.localeCompare(b));
    const result = [...input].sort(byString);

    expect(result).toEqual(expected);
  });
});

describe('byStringWithoutCaseSensitivity', () => {
  it('compares by lexicographic order', () => {
    expect(byString('a', 'B')).toBeLessThan(0);
    expect(byString('B', 'a')).toBeGreaterThan(0);
  });

  it('defines equality', () => {
    expect(byStringWithoutCaseSensitivity('a', 'A')).toBe(0);
  });
});

describe('byCodeUnit', () => {
  it('compares by code unit', () => {
    expect(byCodeUnit('\x00', '\x01')).toBeLessThan(0);
    expect(byCodeUnit('\x01', '\x00')).toBeGreaterThan(0);
  });

  it('defines equality', () => {
    expect(byCodeUnit('\ud83d\udc96', '\ud83d\udc96')).toBe(0);
  });

  it('sorts code units correctly', () => {
    const input = ['[', 'a', ']', ' ', '_', '^', 'Z'];
    const result = [...input].sort(byCodeUnit);

    expect(result).toEqual([' ', 'Z', '[', ']', '^', '_', 'a']);
  });
});

describe('byDate', () => {
  const oneDay = 24 * 60 * 60 * 1000;
  const today = new Date();
  const yesterday = new Date(+today - oneDay);
  const tomorrow = new Date(+today + oneDay);

  it('compares by chronological order', () => {
    expect(byDate(yesterday, today)).toBeLessThan(0);
    expect(byDate(tomorrow, today)).toBeGreaterThan(0);
  });

  it('defines equality', () => {
    expect(byDate(today, today)).toBe(0);
  });

  it('sorts dates correctly', () => {
    const result = [tomorrow, yesterday, today].sort(byDate);

    expect(result).toEqual([yesterday, today, tomorrow]);
  });
});

describe('byBoolean', () => {
  it('compares by truth', () => {
    expect(byBoolean(false, true)).toBeLessThan(0);
    expect(byBoolean(true, false)).toBeGreaterThan(0);
  });

  it('defines equality', () => {
    expect(byBoolean(false, false)).toBe(0);
    expect(byBoolean(true, true)).toBe(0);
  });

  it('sorts booleans correctly', () => {
    const result = [false, true, false, true, false].sort(byBoolean);

    expect(result).toEqual([false, false, false, true, true]);
  });
});