A simple summary and code samples of easy-to-understand java Junit unit tests

Code sample:
2 classes

public class calculator {
    
    
    int add(int x,int y){
    
    
        return  x+y;
    }
    int subtract(int x,int y){
    
    
        return x-y;
    }
    int multiply(int x,int y){
    
    
        return x*y;
    }
    int division(int x,int y){
    
    
        return x/y;
    }

}

import org.junit.Assert;
import org.junit.Test;
public class test {
    
    
    @Test
    public void testadd(){
    
    
        calculator yf=new calculator();
        int result =yf.add(1,2);
        Assert.assertEquals(3,result);
        System.out.println("...........................");

    }


}

Because it is indeed equal to 3, the code is output normally, as follows.

If it is not equal to

import org.junit.Assert;
import org.junit.Test;
public class test {
    
    
    @Test
    public void testadd(){
    
    
        calculator yf=new calculator();
        int result =yf.add(1,2);
        Assert.assertEquals(2,result);//修改在这
        System.out.println("...........................");

    }


}

The result is as follows, the

compiler will automatically report an error

Code sample
only make changes to test

import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
public class test {
    
    
    @Before
    public void before(){
    
    
        System.out.println("这里是before");
    }
     @After
     public void after(){
    
    
        System.out.println("after");
    }


    @Test
    public void testadd(){
    
    
        calculator yf=new calculator();
        int result =yf.add(1,2);
        Assert.assertEquals(2,result);
        System.out.println("...........................");

    }


}

We don’t see the execution order of after here.
Let’s change the code to

import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
public class test {
    
    
    @Before
    public void before(){
    
    
        System.out.println("这里是before");
    }
     @After
     public void after(){
    
    
        System.out.println("after");
    }


    @Test
    public void testadd(){
    
    
        calculator yf=new calculator();
        int result =yf.add(1,2);
        Assert.assertEquals(3,result);
        System.out.println("...........................");

    }


}

This is obvious