add: 最后一个单词的长度

test/string/length-of-last-word.test.js

@@ -0,0 +1,5 @@
+import { lengthOfLastWord } from '../../src/string/length-of-last-word'
+
+test('最后一个单词的长度', () => {
+  expect(lengthOfLastWord('b   a    ')).toBe(1)
+})