[Mockito] Spring Unit Testing with Mockito

It is recommened to write unit testing with Mockito in Spring framework, because it is much faster with Spring framework test. But in case you can doing MVC, you still need to use spring framework test.

In this post, we need to understand why to use Mockito. 

For example, we have two class:

package com.example.in28minutes.cdi;

import javax.inject.Named;

@Named
public class SomeCDIDAO {
    public int[] getData() {
        return new int[] {5,89,100};
    }
}

---

package com.example.in28minutes.cdi;

import javax.inject.Inject;
import javax.inject.Named;

@Named
public class SomeCDIBusiness {

    @Inject
    SomeCDIDAO someCDIDAO;

    public SomeCDIDAO getSomeCDIDAO() {
        return someCDIDAO;
    }

    public void setSomeCDIDAO(SomeCDIDAO someCDIDAO) {
        this.someCDIDAO = someCDIDAO;
    }

    public int findGreatest() {
        int greatest = Integer.MIN_VALUE;
        int[] data = someCDIDAO.getData();
        for (int value : data) {
            if (value > greatest) {
                greatest = value;
            }
        }
        return greatest;
    }
}

'SomeCDIDAO' you can consider this class is mainly dealing with Database, fetech data, inserting data. 'SomeCDIBusiness' is using SomeCDIDAO to fetching data.

Whenever, class is dealing with Database, you should always write tests in Mockito. You should mock the opretaion, instead calling the database for real.

package com.example.in28minutes.cdi;

import com.example.in28minutes.In28minutesBasicApplication;
import com.example.in28minutes.In28minutesCdiApplication;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.junit.MockitoJUnitRunner;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringRunner;

import javax.inject.Inject;

import static org.junit.Assert.assertEquals;
import static org.mockito.Mockito.mock;

// Load the context
@RunWith(MockitoJUnitRunner.class)
public class SomeCdiBusinessTest {

    @InjectMocks
    SomeCDIBusiness someCDIBusiness;

    @Mock
    SomeCDIDAO mockDAO;

    @Test
    public void testBasicScenario () {
        Mockito.when(mockDAO.getData()).thenReturn(new int[] {1,2,3});
        int result = someCDIBusiness.findGreatest();
        assertEquals(3, result);
    }

    @Test
    public void testBasicScenario_null () {
        Mockito.when(mockDAO.getData()).thenReturn(new int[] {});
        int result = someCDIBusiness.findGreatest();
        assertEquals(Integer.MIN_VALUE, result);
    }
}

---

Configuration:

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

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.mockito</groupId>
            <artifactId>mockito-core</artifactId>
            <scope>test</scope>
        </dependency>

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