lesson6中 n===0,1,10都报错了，请问是哪里出问题了？

[dadiu]

具体报错如下图

F:\github\myStudy\node\lesson6>mocha

test/main.test.js
1) should equal 0 when n === 0
2) should equal 1 when n === 1
3) should equal 55 when n === 10
√ should throw when n > 10
√ should throw when n < 0
√ should throw when is not Number

3 passing (35ms)
3 failing

1. test/main.test.js should equal 0 when n === 0:
   AssertionError: expected 0 == undefined
   at Context. (test\main.test.js:7:34)

2. test/main.test.js should equal 1 when n === 1:
   AssertionError: expected 1 == undefined
   at Context. (test\main.test.js:11:34)

3. test/main.test.js should equal 55 when n === 10:
   AssertionError: expected 55 == undefined
   at Context. (test\main.test.js:15:35)