2022-08-08 The fifth group Gu Xiangquan study notes day31-collection-junit unit test

JUnit单元测试

Junit是一个Java语言的单元测试框架

Junit单元测试的好处

1. A series of test methods can be written,Unit test all interfaces or methods of the project
2. 启动后,自动化的测试
3. Just need to see the final result
4. The use cases of each unit test are relatively independent,有Junit启动
5. 添加,删除,Testing of shielding methods

jar包

If the introduction is a third-party plug-in,xxx.jar的文件.
First, import this file into our project directory
凄恻,To be added to the project's since directory

测试方法

1. There can be no return pride
2. 不能有参数列表
3. 必须有Test注解

Junit断言

JunitAll assertions of Assert类中
This class provides many useful assertions to write test cases
Only invalid assertions are logged

asserEquals：Check that the two variables or lighting are balanced
assertTrue：检查条件是否为真
assertFalse：Check if the field is home
assertNot Null：检查对象是否不为空
assertNull：检查对象是否为空

Before：在测试方法之前执行
After：在测试方法之后执行

命名规范：
The naming of the unit test class,被测试类的类名,Test
测试方法的命名,test + The method name of the method being tested

Junit4、Junit5,建议使用4

测试ArrayList与LinkedList

Test tail insertion efficiency(尾插100w个元素)

package com.jsoft.junit;

import org.junit.Test;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;

public class Demo1 {
    

    // 测试ArrayListTail insertion element efficiency
    @Test
    public void testArrayList() {
    
        long begin = System.currentTimeMillis();
        List<Integer> list = new ArrayList<>(1000000);
        long end = System.currentTimeMillis();
        for (int i = 0; i < 1000000; i++) {
    
            list.add(i);
        }
        System.out.println("耗时：" + (end - begin) + "ms");
    }

    // 测试LinkedListTail insertion element efficiency
    @Test
    public void testLinkedList() {
    
        List<Integer> list = new LinkedList<>();
        long begin = System.currentTimeMillis();
        for (int i = 0; i < 1000000; i++) {
    
            list.add(i);
        }
        long end = System.currentTimeMillis();
        System.out.println("耗时：" + (end - begin) + "ms");
    }

}

We tested the results three times,取平均值
ArrayList耗时：1ms (1ms、1ms、1ms)
LinkedList耗时：108ms (115ms、105ms、103ms)

Test the efficiency of random retrieval(对10wrandom retrieval of data10w次)

package com.jsoft.junit;

import org.junit.Test;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Random;

public class Demo1 {
    

    // 测试ArrayListRandom retrieval element efficiency
    @Test
    public void testArrayList() {
    

        // itit
        Random r = new Random();
        List<Integer> list = new ArrayList<>(100000);
        for (int i = 0; i < 100000; i++) {
    
            list.add(i);
        }

        // begin
        long begin = System.currentTimeMillis();
        for (int i = 0; i < list.size(); i++) {
    
            list.get(r.nextInt(list.size()));
        }
        long end = System.currentTimeMillis();
        System.out.println("耗时：" + (end - begin) + "ms");
    }

    // 测试LinkedListRandom retrieval element efficiency
    @Test
    public void testLinkedList() {
    
        // itit
        Random r = new Random();
        List<Integer> list = new LinkedList<>();
        for (int i = 0; i < 100000; i++) {
    
            list.add(i);
        }

        // begin
        long begin = System.currentTimeMillis();
        for (int i = 0; i < list.size(); i++) {
    
            list.get(r.nextInt(list.size()));
        }
        long end = System.currentTimeMillis();
        System.out.println("耗时：" + (end - begin) + "ms");
    }

}

We tested the results three times,取平均值
ArrayList耗时：ms (6ms、5ms、3ms)
LinkedList耗时：ms (5190ms、5158ms、5232ms)