假如你正在使用CoffeeScript并且想要验证功能是否与预期一致，便可以决定使用Nodeunit测试框架。
Nodeunit是一种JavaScript对于单元测试库（ Unit Testing libraries ）中xUnit族的实现，Java, Python, Ruby, Smalltalk中均可以使用。
当使用xUnit族测试框架时，你需要将所需测试的描述预期功能的代码写在一个文件中。
例如，我们希望我们的计算器可以进行加法和减法，并且对于正负数均可以正确计算，我们的测试如下。
# test/calculator.test.coffee
Calculator = require '../calculator'
exports.CalculatorTest =
'test can add two positive numbers': (test) ->
calculator = new Calculator
result = calculator.add 2, 3
test.equal(result, 5)
test.done()
'test can handle negative number addition': (test) ->
calculator = new Calculator
result = calculator.add -10, 5
test.equal(result, -5)
test.done()
'test can subtract two positive numbers': (test) ->
calculator = new Calculator
result = calculator.subtract 10, 6
test.equal(result, 4)
test.done()
'test can handle negative number subtraction': (test) ->
calculator = new Calculator
result = calculator.subtract 4, -6
test.equal(result, 10)
test.done()在可以运行你的测试之前，你必须先安装Nodeunit：
首先创建一个package.json文件
{
"name": "calculator",
"version": "0.0.1",
"scripts": {
"test": "./node_modules/.bin/nodeunit test"
},
"dependencies": {
"coffee-script": "~1.4.0",
"nodeunit": "~0.7.4"
}
}接下来从一个终端运行。
$ npm install使用代码行可以简便地运行测试文件：
$ npm test测试失败，因为我们并没有calculator.coffee
suki@Yuzuki:nodeunit_testing (master)$ npm test
npm WARN package.json calculator@0.0.1 No README.md file found!
> calculator@0.0.1 test /Users/suki/tmp/nodeunit_testing
> ./node_modules/.bin/nodeunit test
/Users/suki/tmp/nodeunit_testing/node_modules/nodeunit/lib/nodeunit.js:72
if (err) throw err;
^
Error: ENOENT, stat '/Users/suki/tmp/nodeunit_testing/test'
npm ERR! Test failed. See above for more details.
npm ERR! not ok code 0我们创建一个简单文件
# calculator.coffee
class Calculator
module.exports = Calculator并且重新运行测试套件。
suki@Yuzuki:nodeunit_testing (master)$ npm test
npm WARN package.json calculator@0.0.1 No README.md file found!
> calculator@0.0.1 test /Users/suki/tmp/nodeunit_testing
> ./node_modules/.bin/nodeunit test
calculator.test
✖ CalculatorTest - test can add two positive numbers
TypeError: Object #<Calculator> has no method 'add'
...
✖ CalculatorTest - test can handle negative number addition
TypeError: Object #<Calculator> has no method 'add'
...
✖ CalculatorTest - test can subtract two positive numbers
TypeError: Object #<Calculator> has no method 'subtract'
...
✖ CalculatorTest - test can handle negative number subtraction
TypeError: Object #<Calculator> has no method 'subtract'
...
FAILURES: 4/4 assertions failed (31ms)
npm ERR! Test failed. See above for more details.
npm ERR! not ok code 0让我们对方法进行实现来观察测试是否可以通过。
# calculator.coffee
class Calculator
add: (a, b) ->
a + b
subtract: (a, b) ->
a - b
module.exports = Calculator当我们重新运行测试时可以看到全部通过：
suki@Yuzuki:nodeunit_testing (master)$ npm test
npm WARN package.json calculator@0.0.1 No README.md file found!
> calculator@0.0.1 test /Users/suki/tmp/nodeunit_testing
> ./node_modules/.bin/nodeunit test
calculator.test
✔ CalculatorTest - test can add two positive numbers
✔ CalculatorTest - test can handle negative number addition
✔ CalculatorTest - test can subtract two positive numbers
✔ CalculatorTest - test can handle negative number subtraction
OK: 4 assertions (27ms)既然测试全部通过，我们应看一看我们的代码或测试是否可以被重构。
在我们的测试文件中，每个测试都创建了自己的calculator实例。这会使我们的测试相当的重复，特别是对于大型的测试套件。理想情况下，我们应该考虑将初始化代码移动到每次测试之前运行。
通常在其他的xUnit库中，Nodeunit会提供一个setUp（以及tearDown）功能会在测试前调用。
Calculator = require '../calculator'
exports.CalculatorTest =
setUp: (callback) ->
@calculator = new Calculator
callback()
'test can add two positive numbers': (test) ->
result = @calculator.add 2, 3
test.equal(result, 5)
test.done()
'test can handle negative number addition': (test) ->
result = @calculator.add -10, 5
test.equal(result, -5)
test.done()
'test can subtract two positive numbers': (test) ->
result = @calculator.subtract 10, 6
test.equal(result, 4)
test.done()
'test can handle negative number subtraction': (test) ->
result = @calculator.subtract 4, -6
test.equal(result, 10)
test.done()我们可以重新运行测试，仍然可以全部通过。