Spring Boot + JUnit 5 + Mockito

In this article, we will show you how to do Spring Boot 2 integration test with JUnit 5, and also Mockito.

• Spring Boot 2.1.2.RELEASE
• JUnit 5
• Mockito 2
• Maven 3

In short, exclude junit4 from spring-boot-starter-test, and include the JUnit 5 jupiter engine manually, done.

Let see the following Spring boot MVC web application, and how to perform unit test with JUnit 5 and mocking with Mockito framework.

1. Maven

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
         http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.favtuts.spring</groupId>
    <artifactId>testing-junit5-mockito</artifactId>
    <version>1.0</version>

    <properties>
        <java.version>1.8</java.version>
        <junit-jupiter.version>5.3.2</junit-jupiter.version>
        <mockito.version>2.24.0</mockito.version>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.2.RELEASE</version>
    </parent>

    <dependencies>

        <!-- mvc -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!-- exclude junit 4 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>junit</groupId>
                    <artifactId>junit</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

        <!-- junit 5 -->
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-engine</artifactId>
            <version>${junit-jupiter.version}</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <optional>true</optional>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-surefire-plugin</artifactId>
                <version>2.22.0</version>
            </plugin>

        </plugins>
    </build>

</project>

Display the project dependencies.

$ mvn dependency:tree

[INFO] com.favtuts.spring:testing-junit5-mockito:jar:1.0
[INFO] +- org.springframework.boot:spring-boot-starter-web:jar:2.1.2.RELEASE:compile
[INFO] |  +- org.springframework.boot:spring-boot-starter:jar:2.1.2.RELEASE:compile
[INFO] |  |  +- org.springframework.boot:spring-boot-starter-logging:jar:2.1.2.RELEASE:compile
[INFO] |  |  |  +- ch.qos.logback:logback-classic:jar:1.2.3:compile
[INFO] |  |  |  |  \- ch.qos.logback:logback-core:jar:1.2.3:compile
[INFO] |  |  |  +- org.apache.logging.log4j:log4j-to-slf4j:jar:2.11.1:compile
[INFO] |  |  |  |  \- org.apache.logging.log4j:log4j-api:jar:2.11.1:compile
[INFO] |  |  |  \- org.slf4j:jul-to-slf4j:jar:1.7.25:compile
[INFO] |  |  +- javax.annotation:javax.annotation-api:jar:1.3.2:compile
[INFO] |  |  \- org.yaml:snakeyaml:jar:1.23:runtime
[INFO] |  +- org.springframework.boot:spring-boot-starter-json:jar:2.1.2.RELEASE:compile
[INFO] |  |  +- com.fasterxml.jackson.core:jackson-databind:jar:2.9.8:compile
[INFO] |  |  |  +- com.fasterxml.jackson.core:jackson-annotations:jar:2.9.0:compile
[INFO] |  |  |  \- com.fasterxml.jackson.core:jackson-core:jar:2.9.8:compile
[INFO] |  |  +- com.fasterxml.jackson.datatype:jackson-datatype-jdk8:jar:2.9.8:compile
[INFO] |  |  +- com.fasterxml.jackson.datatype:jackson-datatype-jsr310:jar:2.9.8:compile
[INFO] |  |  \- com.fasterxml.jackson.module:jackson-module-parameter-names:jar:2.9.8:compile
[INFO] |  +- org.springframework.boot:spring-boot-starter-tomcat:jar:2.1.2.RELEASE:compile
[INFO] |  |  +- org.apache.tomcat.embed:tomcat-embed-core:jar:9.0.14:compile
[INFO] |  |  +- org.apache.tomcat.embed:tomcat-embed-el:jar:9.0.14:compile
[INFO] |  |  \- org.apache.tomcat.embed:tomcat-embed-websocket:jar:9.0.14:compile
[INFO] |  +- org.hibernate.validator:hibernate-validator:jar:6.0.14.Final:compile
[INFO] |  |  +- javax.validation:validation-api:jar:2.0.1.Final:compile
[INFO] |  |  +- org.jboss.logging:jboss-logging:jar:3.3.2.Final:compile
[INFO] |  |  \- com.fasterxml:classmate:jar:1.4.0:compile
[INFO] |  +- org.springframework:spring-web:jar:5.1.4.RELEASE:compile
[INFO] |  |  \- org.springframework:spring-beans:jar:5.1.4.RELEASE:compile
[INFO] |  \- org.springframework:spring-webmvc:jar:5.1.4.RELEASE:compile
[INFO] |     +- org.springframework:spring-aop:jar:5.1.4.RELEASE:compile
[INFO] |     +- org.springframework:spring-context:jar:5.1.4.RELEASE:compile
[INFO] |     \- org.springframework:spring-expression:jar:5.1.4.RELEASE:compile
[INFO] +- org.springframework.boot:spring-boot-starter-test:jar:2.1.2.RELEASE:test
[INFO] |  +- org.springframework.boot:spring-boot-test:jar:2.1.2.RELEASE:test
[INFO] |  +- org.springframework.boot:spring-boot-test-autoconfigure:jar:2.1.2.RELEASE:test
[INFO] |  +- com.jayway.jsonpath:json-path:jar:2.4.0:test
[INFO] |  |  +- net.minidev:json-smart:jar:2.3:test
[INFO] |  |  |  \- net.minidev:accessors-smart:jar:1.2:test
[INFO] |  |  |     \- org.ow2.asm:asm:jar:5.0.4:test
[INFO] |  |  \- org.slf4j:slf4j-api:jar:1.7.25:compile
[INFO] |  +- org.assertj:assertj-core:jar:3.11.1:test
[INFO] |  +- org.mockito:mockito-core:jar:2.24.0:test
[INFO] |  |  +- net.bytebuddy:byte-buddy:jar:1.9.7:test
[INFO] |  |  +- net.bytebuddy:byte-buddy-agent:jar:1.9.7:test
[INFO] |  |  \- org.objenesis:objenesis:jar:2.6:test
[INFO] |  +- org.hamcrest:hamcrest-core:jar:1.3:test
[INFO] |  +- org.hamcrest:hamcrest-library:jar:1.3:test
[INFO] |  +- org.skyscreamer:jsonassert:jar:1.5.0:test
[INFO] |  |  \- com.vaadin.external.google:android-json:jar:0.0.20131108.vaadin1:test
[INFO] |  +- org.springframework:spring-core:jar:5.1.4.RELEASE:compile
[INFO] |  |  \- org.springframework:spring-jcl:jar:5.1.4.RELEASE:compile
[INFO] |  +- org.springframework:spring-test:jar:5.1.4.RELEASE:test
[INFO] |  \- org.xmlunit:xmlunit-core:jar:2.6.2:test
[INFO] |     \- javax.xml.bind:jaxb-api:jar:2.3.1:test
[INFO] |        \- javax.activation:javax.activation-api:jar:1.2.0:test
[INFO] +- org.junit.jupiter:junit-jupiter-engine:jar:5.3.2:test
[INFO] |  +- org.apiguardian:apiguardian-api:jar:1.0.0:test
[INFO] |  +- org.junit.platform:junit-platform-engine:jar:1.3.2:test
[INFO] |  |  +- org.junit.platform:junit-platform-commons:jar:1.3.2:test
[INFO] |  |  \- org.opentest4j:opentest4j:jar:1.1.1:test
[INFO] |  \- org.junit.jupiter:junit-jupiter-api:jar:5.3.2:test
[INFO] \- org.springframework.boot:spring-boot-devtools:jar:2.1.2.RELEASE:compile (optional)
[INFO]    +- org.springframework.boot:spring-boot:jar:2.1.2.RELEASE:compile
[INFO]    \- org.springframework.boot:spring-boot-autoconfigure:jar:2.1.2.RELEASE:compile

2. Test Spring Boot + JUnit 5 + Mockito.

2.1 Test the following Spring components.

HelloServiceImpl.java

package com.favtuts.core.services;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.favtuts.core.repository.HelloRepository;

@Service
public class HelloServiceImpl implements HelloService {

    @Autowired
    HelloRepository helloRepository;

    @Override
    public String get() {
        return helloRepository.get();
    }
    
}

HelloRepositoryImpl.java

package com.favtuts.core.repository;

import org.springframework.stereotype.Repository;

@Repository
public class HelloRepositoryImpl implements HelloRepository {
    @Override
    public String get() {
        return "Hello JUnit 5";
    }
}

2.2 JUnit 5

HelloServiceTest.java

package com.favtuts.core.services;

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

//https://docs.spring.io/spring-boot/docs/2.1.2.RELEASE/reference/htmlsingle/#boot-features-testing-spring-boot-applications
@SpringBootTest
public class HelloServiceTest {
    
    @Autowired
    HelloService helloService;

    @DisplayName("Test Spring @Autowired Integration")
    @Test
    void testGet() {
        assertEquals("Hello JUnit 5", helloService.get());
    }
}

2.3 Mockito.

HelloServiceMockTest.java

package com.favtuts.core.services;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.mockito.Mockito.when;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.springframework.boot.test.context.SpringBootTest;

import com.favtuts.core.repository.HelloRepository;

@SpringBootTest
public class HelloServiceMockTest {
    
    @Mock
    private HelloRepository helloRepository;

    @InjectMocks // auto inject helloRepository
    private HelloService helloService = new HelloServiceImpl();

    @BeforeEach
    void setMockOutput() {
        when(helloRepository.get()).thenReturn("Hello Mockito From Repository");
    }

    @DisplayName("Test Mock helloService + helloRepository")
    @Test
    void testGet() {
        assertEquals("Hello Mockito From Repository", helloService.get());
    }
}

3. Test Spring MVC Controller.

3.1 MVC controller.

MainController.java

package com.favtuts.core.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class MainController {
    
    @ResponseBody
    @GetMapping("/")
    public String hello() {
        return "Hello Controller";
    }
}

3.2 JUnit 5 and MVC test.

MainControllerTest.java

package com.favtuts.core.controller;

import static org.junit.jupiter.api.Assertions.assertEquals;

import java.net.URL;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
import org.springframework.boot.test.web.client.TestRestTemplate;
import org.springframework.boot.web.server.LocalServerPort;
import org.springframework.http.ResponseEntity;

@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
public class MainControllerTest {
    
    // bind the above RANDOM_PORT
    @LocalServerPort
    private int port;

    @Autowired
    private TestRestTemplate restTemplate;

    @Test
    public void getHello() throws Exception {

        ResponseEntity<String> response = restTemplate.getForEntity(
            new URL("http://localhost:" + port + "/").toString(), String.class);
        assertEquals("Hello Controller", response.getBody());
    }
}

Done.

Download Source Code

$ git clone https://github.com/favtuts/java-spring-boot-tutorials.git
$ cd testing-junit5-mockito
$ mvn test

References

• Spring Boot Testing
• Mockito: Why You Should Not Use InjectMocks Annotation to Autowire Fields
• JUnit 5 user guide