Unit testing basics using jest

The meaning of unit testing

1. Check the safety and reliability of functional modules

2. Check whether the function function operates as expected

3. Detect potential problems and defects

4. Make the role of functional modules clearer, understand the code effectively, and assist in development.

jest use

Plug-in download and installation

npm i -D jest

Instructions

npm test

 Modify package.json

  "scripts": {
    "test": "jest"
  },

test passed

code

let addFun = (val1,val2)=>{return val1+val2}
let numberFun = (value)=>{
    return value>0
}
let errorFun = (value)=>{
   try{
    let a = b
    return a
   }catch(err){
    console.log(err)
    return false
   }
}

test('addFun方法测试',()=>{
    expect(addFun(1,2)).toBe(3)
}) 
test('numberFun方法测试',()=>{
    expect(numberFun(10)).toBe(true)
})
test('errorFun方法测试',()=>{
    // expect(errorFun(null)).toBe(true)
    expect(errorFun(null)).toBe(false)
})

operation result

 Test failed

code

let addFun = (val1,val2)=>{return val1+val2}
let numberFun = (value)=>{
    return value>0
}
let errorFun = (value)=>{
   try{
    let a = b
    return a
   }catch(err){
    console.log(err)
    return false
   }
}

test('addFun方法测试',()=>{
    expect(addFun(1,2)).toBe(3)
}) 
test('numberFun方法测试',()=>{
    expect(numberFun(10)).toBe(true)
})
test('errorFun方法测试',()=>{
     expect(errorFun(null)).toBe(true)
    //expect(errorFun(null)).toBe(false)
})

 operation result