Spring boot, mockito and junit – unit test service layer

学习使用**JUnit** 和 Mockito 测试框架为Spring 应用service层编写单元测试。这个教程演示_spring boot_ 测试service层案例。

1. Maven 依赖

spring-boot-starter-test 包含创建和执行单元测试的所有必须依赖。

pom.xml

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-test</artifactId>
</dependency>

如果你不使用 spring boot 你就需要加入下面的依赖：

pom.xml

<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.mockito</groupId>
    <artifactId>mockito-core</artifactId>
    <version>2.15.0</version>
</dependency>
<dependency>
    <groupId>org.mockito</groupId>
    <artifactId>mockito-inline</artifactId>
    <version>2.15.0</version>
</dependency>

2. 创建项目

在这个案例中，我们的单元测试主要有2个classes EmployeeManager 和 EmployeeDao 顾名思义，manager class 代表是service 层，dao class 是和数据库打交道的。

EmployeeManager 依赖 EmployeeDao 并且委托方法调用获取数据，最终将数据返回到controller.

为了测试EmployeeManager 中的方法，我们可以通过以下2种方式创建TestEmployeeManager JUnit 单元测试类：

2.1. MockitoJUnitRunner class

MockitoJUnitRunner 自动初始化所有被@Mock 和 @InjectMocks 注解的对象。

TestEmployeeManager.java

@RunWith(MockitoJUnitRunner.class)

public class TestEmployeeManager {
    @InjectMocks
    EmployeeManager manager;

    @Mock
    EmployeeDao dao;
    //tests
}

2.2. MockitoAnnotations.initMocks() 方法

如果我们没有使用MockitoJUnitRunner 这种方式，那么我们可以使用static 方法MockitoAnnotations.initMocks()。这个方法，也能在初始化junit tests是，实例化mock 对象。

TestEmployeeManager.java

public class TestEmployeeManager {

    @InjectMocks
    EmployeeManager manager;

    @Mock
    EmployeeDao dao;

    @Before
    public void init() {
        MockitoAnnotations.initMocks(this);
    }
    //tests

}

2.3. @Mock 与 @InjectMocks 对比

The @Mock annotation creates a mock implementation for the class it is annotated with.
@Mock 注解可以为被注解的类创建一个模拟实现类。
@InjectMocks also creates the mock implementation, additionally injects the dependent mocks that are marked with the annotations @Mockinto it.
@InjectMocks 也可以创建模拟对象实现类，另外还可以为标记@Mock对象注入模拟对象实现

In above example, we have annotated EmployeeManager class with @InjectMocks, so mockito will create the mock object for EmployeeManager class and inject the mock dependency of EmployeeDao into it.

在上面的示例，我们EmployeeManager 被@InjectMocks注解，因此mockito 将会为EmployeeManager 创建模拟对象并且注入模拟的对象依赖 EmployeeDao。

3. 在JUnit使用Mockito编写单元测试

让我们来看几个为service 层方法编写mockito 模拟对象的单元测试。

几个示例方法 getAllEmployees()将会返回EmployeeVO对象集合，getEmployeeById(int id)将会返回指定id employee 对象；

createEmployee()将会增加一个employee 并且返回 void。

3.1. Service 层单元测试

TestEmployeeManager.java

package com.howtodoinjava.demo;

import static org.junit.Assert.assertEquals;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;
import java.util.ArrayList;
import java.util.List;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.mockito.junit.MockitoJUnitRunner;
import com.howtodoinjava.demo.dao.EmployeeDao;
import com.howtodoinjava.demo.model.EmployeeVO;
import com.howtodoinjava.demo.service.EmployeeManager;

public class TestEmployeeManager {

    @InjectMocks
    EmployeeManager manager;

    @Mock
    EmployeeDao dao;

    @Before
    public void init() {
        MockitoAnnotations.initMocks(this);
    }

    @Test
    public void getAllEmployeesTest()
    {
        List<EmployeeVO> list = new ArrayList<EmployeeVO>();
        EmployeeVO empOne = new EmployeeVO(1, "John", "John", "howtodoinjava@gmail.com");
        EmployeeVO empTwo = new EmployeeVO(2, "Alex", "kolenchiski", "alexk@yahoo.com");
        EmployeeVO empThree = new EmployeeVO(3, "Steve", "Waugh", "swaugh@gmail.com");
         
        list.add(empOne);
        list.add(empTwo);
        list.add(empThree);
        
        when(dao.getEmployeeList()).thenReturn(list);
        //test
        List<EmployeeVO> empList = manager.getEmployeeList();
        assertEquals(3, empList.size());
        verify(dao, times(1)).getEmployeeList();
    }

    @Test
    public void getEmployeeByIdTest()
    {
        when(dao.getEmployeeById(1)).thenReturn(new EmployeeVO(1,"Lokesh","Gupta","user@email.com"));
        EmployeeVO emp = manager.getEmployeeById(1);
        assertEquals("Lokesh", emp.getFirstName());
        assertEquals("Gupta", emp.getLastName());
        assertEquals("user@email.com", emp.getEmail());
    }

    @Test
    public void createEmployeeTest()
    {
        EmployeeVO emp = new EmployeeVO(1,"Lokesh","Gupta","user@email.com");
        manager.addEmployee(emp);
        verify(dao, times(1)).addEmployee(emp);
    }
}

单元测试的结果如下

Spring boot, mockito and junit – 单元测试service层

Spring boot mockito junit 示例

3.2. Service 层

EmployeeManager.java

import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.howtodoinjava.demo.dao.EmployeeDao;
import com.howtodoinjava.demo.model.EmployeeVO;

@Service
public class EmployeeManager
{
    @Autowired
    EmployeeDao dao;     

    public List<EmployeeVO> getEmployeeList() {
        return dao.getEmployeeList();
    }     

    public EmployeeVO getEmployeeById(int id) {
        return dao.getEmployeeById(id);
    }

    public void addEmployee(EmployeeVO employee) {
        dao.addEmployee(employee);
    }
}

3.3. Dao 层

EmployeeDao.java

package com.howtodoinjava.demo.dao;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.springframework.stereotype.Repository;
import com.howtodoinjava.demo.model.EmployeeVO;

@Repository
public class EmployeeDao {

    private Map<Integer, EmployeeVO> DB = new HashMap<>();
     
    public List<EmployeeVO> getEmployeeList()
    {
        List<EmployeeVO> list = new ArrayList<>();
        if(list.isEmpty()) {
            list.addAll(DB.values());
        }
        return list;
    }
  
    public EmployeeVO getEmployeeById(int id) {
        return DB.get(id);
    }

    public void addEmployee(EmployeeVO employee) {
        employee.setEmployeeId(DB.keySet().size() + 1);
        DB.put(employee.getEmployeeId(), employee);
    }

    public void updateEmployee(EmployeeVO employee) {
        DB.put(employee.getEmployeeId(), employee);
    }

    public void deleteEmployee(int id) {
        DB.remove(id);
    }

}