Jest-1

前言

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本系列内容基本上按照官网的示例来讲解如何入门。

匹配器

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首先讲匹配器，是单元测试最基础的部分，一般称为断言，如：assert，tap，chai，should等断言库。Jest内置了断言库，正式场景中不需引入断言库。
我们从基本类型讲起，

字符串

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it('"" toBe ""', () => {
    expect('').toBe('')
})
it('"" toEqual ""', () => {
    expect('').toEqual('')
})
it('"1" not toBe ""', () => {
    // 逆向断言
    expect('1').not.toBe('')
})
it('"1" not toEqual ""', () => {
    expect('1').not.toEqual('')
})
it('"1" not toEqual 1', () => {
    expect('1').not.toEqual(1)
})
it('"1" not toBe 1', () => {
    expect('1').not.toBe(1)
})
it('"hello world" toMatch "/world/"', () => {
    // 正则匹配器
    expect('hello world').toMatch(/world/)
})
it('"hello world" not toMatch "/world~/"', () => {
    expect('hello world').not.toMatch(/world~/)
})
it('"hello world" toContain "world"', () => {
    // 交集
    expect('hello world').toContain('world')
})
it('"hello world" is String', () => {
    expect('hello world').toEqual(expect.any(String))
})
it('"hello world" is not Number', () => {
    // 类型判断
    expect('hello world').not.toEqual(expect.any(Number))
})
it('"hello wordl" toHaveLength 11', () => {
    // 长度判断
    expect('hello wordl').toHaveLength(11)
})

数字

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it('12 toBe 12', () => {
    expect(12).toBe(12)
})
it('0.1+0.2 not toBe 0.3', () => {
    expect(0.1+0.2).not.toBe(0.3)
})
it('0.1+0.2 toBeCloseTo 0.3', () => {
    // 无限接近
    expect(0.1+0.2).toBeCloseTo(0.3)
})
it('0.1+0.2 toBeGreaterThan 0.3', () => {
    expect(0.1+0.2).toBeGreaterThan(0.3)
})
it('0.1+0.2 not toBeLessThan 0.3', () => {
    expect(0.1+0.2).not.toBeLessThan(0.3)
})
it('1+2 toBeGreaterThanOrEqual 3', () => {
    expect(1+2).toBeGreaterThanOrEqual(3)
})
it('1+2 toBeLessThanOrEqual 3', () => {
    expect(1+2).toBeLessThanOrEqual(3)
})

数组

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test('[1,2,3,4,500] not toBe [1,2,3,4,500]', () => {
    expect([1,2,3,4,500]).not.toBe([1,2,3,4,500])
})
test('[1,2,3,4,500] toEqual [1,2,3,4,500]', () => {
    expect([1,2,3,4,500]).toEqual([1,2,3,4,500])
})
test('[1,2,3,4,500] toContain 500', () => {
    expect([1,2,3,4,500]).toContain(500)
})
test('[1,2,3,4,500] not toContain "500"', () => {
    expect([1,2,3,4,500]).not.toContain('500')
})
test('[1,[2],3,4,500] not toContain 2', () => {
    expect([1,[2],3,4,500]).not.toContain(2)
})
test('[1,[2],3,4,500] toContain [2]', () => {
    // 多维数组交集多个
    expect([1,[2],3,4,500]).toEqual(expect.arrayContaining([[2]]))
})
test('[1,3,4,500] arrayContanin [3,4]', () => {
    // 一维数组交集多个
    expect([1,[2],3,4,500]).toEqual(expect.arrayContaining([3,4]))
})
it('["hello wordl"] toHaveLength 1', () => {
    expect(['hello wordl']).toHaveLength(1)
})
it('stringMatching', () => {
    const helloworld = [
        'hello',
        'world'
    ]
    const sm = [
        expect.stringMatching(/^hell/),
        expect.stringMatching(/^wo/),
    ]
    // 遍历交集
    expect(helloworld).toEqual(expect.arrayContaining(sm))
})

布尔

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it('false toBeFalsy', () => {
    expect(false).toBeFalsy()
})
it('"" toBeFalsy', () => {
    expect("").toBeFalsy()
})
it('0 toBeFalsy', () => {
    expect(0).toBeFalsy()
})
it('null toBeFalsy', () => {
    expect(null).toBeFalsy()
})
it('undefined toBeFalsy', () => {
    expect(undefined).toBeFalsy()
})
it('NaN toBeFalsy', () => {
    expect(NaN).toBeFalsy()
})
it('everything toBeTruthy', () => {
    expect(1).toBeTruthy()
})

函数

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function sum(a) {
    return a
}
// 基于mock fn
const func = jest.fn((a, b)=>(a + b))
const func2 = jest.fn((a, b)=>(a + b))
it('func toHaveBeenCalledWith 3, 2', () => {
    func(3, 2)
    // 调用时的参数3，2
    expect(func).toHaveBeenCalledWith(3, 2)
})
it('func toHaveBeenCalled', () => {
    // 已被调用
    expect(func).toHaveBeenCalled()
})
it('func toHaveBeenLastCalled', () => {
    func(9, 9)
    // 最后一次被调用
    expect(func).toHaveBeenLastCalledWith(9, 9)
})
it('func2 toHaveBeenCalled', () => {
    expect(func2).not.toHaveBeenCalled()
})
it('func toHaveBeenCalledTimes 2', () => {
    // 被调用两次
    expect(func).toHaveBeenCalledTimes(2)
})
it('func toThrowError ', () => {
    const throwFunc = function (data){
        throw new Error('...error')
    }
    // 抛出错误
    expect(throwFunc).toThrowError('...error')
})
it('func toThrow', () => {
    expect(() => {
        throw new Error()
    }).toThrow()
})

对象

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it('{hello: "world"} toHaveProperty hello', () => {
    const helloworld = {hello: 'world'}
    // 属性检测
    expect(helloworld).toHaveProperty('hello')
})
it('{hello: "world"} not toHaveProperty hello:"google"', () => {
    const helloworld = {hello: 'world'}
    expect(helloworld).not.toHaveProperty('hello', 'google')
})
it('{hello: {world: "one"} deep referencing hello.world', () => {
    const helloworld = {hello: {world: 'one'}}
    // deep属性
    expect(helloworld).toHaveProperty('hello.world', 'one')
})
it('[{hello: 1, world: 2, every: 3}] toContainEqual {world: 2, every: 3}', () => {
    // 数组或者是可被数组化（Array.from）的类数组对象
    const helloworldevery = [{
        world: 2,
        every: 3
    },{
        hello: 1,
        world: 2
    },{
        every: 3
    }]
    const worldevery = {
        world: 2,
        every: 3
    }
    // 部分对象检测
    expect(helloworldevery).toContainEqual(worldevery)
})
it('现有的对象满足我期望的对象', () => {
    const feature = {
        height: 177,
        width: 90,
        padding: {
            top: 20,
            bottom: 20
        },
        content: ['h','e','l','l','o']
    }
    const current = {
        height: 177,
        width: 90,
        padding: {
            top: 20,
            bottom: 20,
            left: 20,
            right: 20
        },
        content: ['h','e','l','l','o'],
        checked: false
    }
    // 整个对象集合检测
    expect(current).toMatchObject(feature)
})
it('A toBeInstanceOf Class A', () => {
    function A() {}
    function B() {}
    const newA = new A()
    // 实例检测
    expect(newA).toBeInstanceOf(A)
})

其他

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it('undefined toBeUndefined', () => {
    expect(undefined).toBeUndefined()
})

it('null toBeUndefined', () => {
    expect(null).toBeNull()
})

小结

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以上总的讲述了Expect基本的使用API，接下来讲一讲另一个重要的方法mock。