text-utils-spec.js

const textUtils = require('../src/text-utils');

describe('text utilities', () => {
  describe('.hasPairedCharacter(string)', () =>
    it('returns true when the string contains a surrogate pair, variation sequence, or combined character', () => {
      expect(textUtils.hasPairedCharacter('abc')).toBe(false);
      expect(textUtils.hasPairedCharacter('a\uD835\uDF97b\uD835\uDF97c')).toBe(
        true
      );
      expect(textUtils.hasPairedCharacter('\uD835\uDF97')).toBe(true);
      expect(textUtils.hasPairedCharacter('\u2714\uFE0E')).toBe(true);
      expect(textUtils.hasPairedCharacter('e\u0301')).toBe(true);

      expect(textUtils.hasPairedCharacter('\uD835')).toBe(false);
      expect(textUtils.hasPairedCharacter('\uDF97')).toBe(false);
      expect(textUtils.hasPairedCharacter('\uFE0E')).toBe(false);
      expect(textUtils.hasPairedCharacter('\u0301')).toBe(false);

      expect(textUtils.hasPairedCharacter('\uFE0E\uFE0E')).toBe(false);
      expect(textUtils.hasPairedCharacter('\u0301\u0301')).toBe(false);
    }));

  describe('.isPairedCharacter(string, index)', () =>
    it('returns true when the index is the start of a high/low surrogate pair, variation sequence, or combined character', () => {
      expect(
        textUtils.isPairedCharacter('a\uD835\uDF97b\uD835\uDF97c', 0)
      ).toBe(false);
      expect(
        textUtils.isPairedCharacter('a\uD835\uDF97b\uD835\uDF97c', 1)
      ).toBe(true);
      expect(
        textUtils.isPairedCharacter('a\uD835\uDF97b\uD835\uDF97c', 2)
      ).toBe(false);
      expect(
        textUtils.isPairedCharacter('a\uD835\uDF97b\uD835\uDF97c', 3)
      ).toBe(false);
      expect(
        textUtils.isPairedCharacter('a\uD835\uDF97b\uD835\uDF97c', 4)
      ).toBe(true);
      expect(
        textUtils.isPairedCharacter('a\uD835\uDF97b\uD835\uDF97c', 5)
      ).toBe(false);
      expect(
        textUtils.isPairedCharacter('a\uD835\uDF97b\uD835\uDF97c', 6)
      ).toBe(false);

      expect(textUtils.isPairedCharacter('a\u2714\uFE0E', 0)).toBe(false);
      expect(textUtils.isPairedCharacter('a\u2714\uFE0E', 1)).toBe(true);
      expect(textUtils.isPairedCharacter('a\u2714\uFE0E', 2)).toBe(false);
      expect(textUtils.isPairedCharacter('a\u2714\uFE0E', 3)).toBe(false);

      expect(textUtils.isPairedCharacter('\uD835')).toBe(false);
      expect(textUtils.isPairedCharacter('\uDF97')).toBe(false);
      expect(textUtils.isPairedCharacter('\uFE0E')).toBe(false);
      expect(textUtils.isPairedCharacter('\uFE0E')).toBe(false);

      expect(textUtils.isPairedCharacter('\uFE0E\uFE0E')).toBe(false);

      expect(textUtils.isPairedCharacter('ae\u0301c', 0)).toBe(false);
      expect(textUtils.isPairedCharacter('ae\u0301c', 1)).toBe(true);
      expect(textUtils.isPairedCharacter('ae\u0301c', 2)).toBe(false);
      expect(textUtils.isPairedCharacter('ae\u0301c', 3)).toBe(false);
      expect(textUtils.isPairedCharacter('ae\u0301c', 4)).toBe(false);
    }));

  describe('.isDoubleWidthCharacter(character)', () =>
    it('returns true when the character is either japanese, chinese or a full width form', () => {
      expect(textUtils.isDoubleWidthCharacter('我')).toBe(true);

      expect(textUtils.isDoubleWidthCharacter('私')).toBe(true);

      expect(textUtils.isDoubleWidthCharacter('Ｂ')).toBe(true);
      expect(textUtils.isDoubleWidthCharacter('，')).toBe(true);
      expect(textUtils.isDoubleWidthCharacter('￠')).toBe(true);

      expect(textUtils.isDoubleWidthCharacter('a')).toBe(false);
    }));

  describe('.isHalfWidthCharacter(character)', () =>
    it('returns true when the character is an half width form', () => {
      expect(textUtils.isHalfWidthCharacter('ﾊ')).toBe(true);
      expect(textUtils.isHalfWidthCharacter('ﾋ')).toBe(true);
      expect(textUtils.isHalfWidthCharacter('ﾬ')).toBe(true);
      expect(textUtils.isHalfWidthCharacter('￭')).toBe(true);

      expect(textUtils.isHalfWidthCharacter('B')).toBe(false);
    }));

  describe('.isKoreanCharacter(character)', () =>
    it('returns true when the character is a korean character', () => {
      expect(textUtils.isKoreanCharacter('우')).toBe(true);
      expect(textUtils.isKoreanCharacter('가')).toBe(true);
      expect(textUtils.isKoreanCharacter('ㅢ')).toBe(true);
      expect(textUtils.isKoreanCharacter('ㄼ')).toBe(true);

      expect(textUtils.isKoreanCharacter('O')).toBe(false);
    }));

  describe('.isWrapBoundary(previousCharacter, character)', () =>
    it('returns true when the character is CJK or when the previous character is a space/tab', () => {
      const anyCharacter = 'x';
      expect(textUtils.isWrapBoundary(anyCharacter, '我')).toBe(true);
      expect(textUtils.isWrapBoundary(anyCharacter, '私')).toBe(true);
      expect(textUtils.isWrapBoundary(anyCharacter, 'Ｂ')).toBe(true);
      expect(textUtils.isWrapBoundary(anyCharacter, '，')).toBe(true);
      expect(textUtils.isWrapBoundary(anyCharacter, '￠')).toBe(true);
      expect(textUtils.isWrapBoundary(anyCharacter, 'ﾊ')).toBe(true);
      expect(textUtils.isWrapBoundary(anyCharacter, 'ﾋ')).toBe(true);
      expect(textUtils.isWrapBoundary(anyCharacter, 'ﾬ')).toBe(true);
      expect(textUtils.isWrapBoundary(anyCharacter, '￭')).toBe(true);
      expect(textUtils.isWrapBoundary(anyCharacter, '우')).toBe(true);
      expect(textUtils.isWrapBoundary(anyCharacter, '가')).toBe(true);
      expect(textUtils.isWrapBoundary(anyCharacter, 'ㅢ')).toBe(true);
      expect(textUtils.isWrapBoundary(anyCharacter, 'ㄼ')).toBe(true);

      expect(textUtils.isWrapBoundary(' ', 'h')).toBe(true);
      expect(textUtils.isWrapBoundary('\t', 'h')).toBe(true);
      expect(textUtils.isWrapBoundary('a', 'h')).toBe(false);
    }));
});