# Unit Test

能針對每個環節進行測試，這是函數式程式設計的優點之一，而Packhouse提供了一種簡單的Mock方法能應付所有細節：

{% hint style="info" %}
Test是一個[Plugin](/the-instance/plugin.md)，使用前必須先引用：
{% endhint %}

```javascript
let Test = require('packhouse/plugins/Test')
let Packhouse = require('Packhouse')
let packhouse = new Packhouse()

packhouse.plugin(Test)

let group = {
    tools: {
        sum: {
            handler(self, v1, v2) {
                self.success(v1 + v2)
            }
        }
    }
}

packhouse.addGroup('math', () => ({ data: group }))

// mock options
packhouse.test.mock('tool', 'math/sum', options => {
    options.handler = self => self.success(50)
})

packhouse.tool('math/sum').action(10, 20, (error, result) => {
    console.log(result) // 50
})

// restore
packhouse.test.restore('tool', 'math/sum')

packhouse.tool('math/sum').action(10, 20, (error, result) => {
    console.log(result) // 30
})
```

### Restore All

將所有Mock物件回到原樣：

```javascript
packhouse.test.restoreAll()
```

## 使用mocha與chai

[mocha](https://mochajs.org/)與[chai](https://www.chaijs.com/)分別為單元測試庫與斷言庫，這只是一個泛用測試組合，以下範例說明如何應用Packhouse進行測試：

```javascript
let { expect } = require('chai')
let Test = require('packhouse/plugins/Test')
let Packhouse = require('Packhouse')
let packhouse = new Packhouse()

packhouse.plugin(Test)

let group = {
    tools: {
        sum: {
            handler(self, v1, v2) {
                self.success(v1 + v2)
            }
        }
    }
}

describe('#Test', function() {
    this.timeout(0)
    before(function() {
        packhouse.test.mock('tool', 'math/sum', options => {
            options.handler = self => self.success(50)
        })
    })

    after(function() {
        packhouse.test.restore('tool', 'math/sum')
    })

    it('test', function(done) {
        packhouse.tool('math/sum').action(10, 10, (error, result) => {
            expect(result).to.equal(50)
        })
    })
})
```


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