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Spring MockMvc tutorial

Spring MockMvc tutorial shows how to test Spring MVC application with MockMvc.

Spring is a popular Java application framework for creating enterprise applications.

MockMvc

MockMvc is defined as a main entry point for server-side Spring MVC testing. Tests with MockMvc lie somewhere between between unit and integration tests.

Spring MockMvc example

The following application uses MockMvc to test a Spring MVC application. We create a test for a template and for a RESTful controller method.

pom.xml
src
├───main
│   ├───java
│   │   └───com
│   │       └───zetcode
│   │           ├───config
│   │           │       MyWebInitializer.java
│   │           │       WebConfig.java
│   │           └───controller
│   │                   MyController.java
│   ├───resources
│   └───webapp
│       └───WEB-INF
│           └───templates
│                   index.html
└───test
    └───java
        └───com
            └───zetcode
                └───controller
                        MyControllerTest.java

This is the project structure.

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.zetcode</groupId>
    <artifactId>mockmvcex</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>war</packaging>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>11</maven.compiler.source>
        <maven.compiler.target>11</maven.compiler.target>
        <spring-version>5.1.3.RELEASE</spring-version>
    </properties>

    <dependencies>

        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <version>1.2.3</version>
        </dependency>

        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.1</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring-version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring-version}</version>
        </dependency>

        <dependency>
            <groupId>org.thymeleaf</groupId>
            <artifactId>thymeleaf-spring5</artifactId>
            <version>3.0.11.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.thymeleaf</groupId>
            <artifactId>thymeleaf</artifactId>
            <version>3.0.11.RELEASE</version>
        </dependency>

    </dependencies>

    <build>
        <plugins>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-war-plugin</artifactId>
                <version>3.2.2</version>
            </plugin>

        </plugins>
    </build>
</project>

In the pom.xml file we have the following dependencies: logback-classic, javax.servlet-api, junit, spring-webmvc, spring-test, thymeleaf-spring5 and thymeleaf.

com/zetcode/config/MyWebInitializer.java
package com.zetcode.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

@Configuration
public class MyWebInitializer extends
        AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return null;
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        
        return new Class[]{WebConfig.class};
    }

    @Override
    protected String[] getServletMappings() {
        
        return new String[]{"/"};
    }
}

MyWebInitializer registers the Spring DispatcherServlet, which is a front controller for a Spring web application.

@Override
protected Class<?>[] getServletConfigClasses() {
    
    return new Class[]{WebConfig.class};
}

The getServletConfigClasses() returns a web configuration class.

com/zetcode/config/WebConfig.java
package com.zetcode.config;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.ViewResolver;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;
import org.springframework.web.servlet.config.annotation.ViewResolverRegistry;
import org.thymeleaf.spring5.SpringTemplateEngine;
import org.thymeleaf.spring5.templateresolver.SpringResourceTemplateResolver;
import org.thymeleaf.spring5.view.ThymeleafViewResolver;

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = {"com.zetcode"})
public class WebConfig {

    @Autowired
    private ApplicationContext applicationContext;

    @Bean
    public SpringResourceTemplateResolver templateResolver() {

        var templateResolver = new SpringResourceTemplateResolver();

        templateResolver.setApplicationContext(applicationContext);
        templateResolver.setPrefix("/WEB-INF/templates/");
        templateResolver.setSuffix(".html");

        return templateResolver;
    }

    @Bean
    public SpringTemplateEngine templateEngine() {

        var templateEngine = new SpringTemplateEngine();
        templateEngine.setTemplateResolver(templateResolver());
        templateEngine.setEnableSpringELCompiler(true);

        return templateEngine;
    }

    @Bean
    public ViewResolver viewResolver() {

        var resolver = new ThymeleafViewResolver();
        var registry = new ViewResolverRegistry(null, applicationContext);

        resolver.setTemplateEngine(templateEngine());
        registry.viewResolver(resolver);

        return resolver;
    }
}

The WebConfig enables Spring MVC annotations with @EnableWebMvc and configures component scanning for the com.zetcode package. It sets up the Thymeleaf engine.

com/zetcode/controller/MyController.java
package com.zetcode.controller;

import org.springframework.http.MediaType;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.time.LocalDateTime;

@Controller
public class MyController {

    @GetMapping(value = "/", produces = MediaType.TEXT_HTML_VALUE)
    public String home(Model model) {

        model.addAttribute("now", LocalDateTime.now());

        return "index";
    }

    @GetMapping(value = "/message", produces = MediaType.TEXT_PLAIN_VALUE)
    @ResponseBody
    public String message() {

        return "Hello there!";
    }
}

MyController provides two handler methods. The home() method return a view with a single attribute and the message() method returns a plain text message. In our tests we test these two methods.

WEB-INF/templates/index.html
<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Home page</title>
</head>
<body>

<p>
Today is: <span th:text="${now}"></span>
</p>

</body>
</html>

This is the index.html view.

com/zetcode/controller/MyControllerTest.java
package com.zetcode.controller;

import org.junit.Before;
import org.junit.Test;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.result.MockMvcResultHandlers;
import org.springframework.test.web.servlet.setup.MockMvcBuilders;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.content;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.view;

public class MyControllerTest {

    private MockMvc mockMvc;

    @Before
    public void setup() {
        this.mockMvc = MockMvcBuilders.standaloneSetup(new MyController()).build();
    }

    @Test
    public void testHomePage() throws Exception {
        this.mockMvc.perform(get("/"))
                .andExpect(status().isOk())
                .andExpect(view().name("index"))
                .andDo(MockMvcResultHandlers.print())
                .andReturn();
    }

    @Test
    public void testMessagePage() throws Exception {
        this.mockMvc.perform(get("/message")).andExpect(status().isOk())
                .andExpect(content().string("Hello there!"));
    }
}

MyControllerTest tests the two handlers.

private MockMvc mockMvc;

@Before
public void setup() {
    this.mockMvc = MockMvcBuilders.standaloneSetup(new MyController()).build();
}

We set up the MockMvc. We add the MyController to the standalone setup. The MockMvcBuilders.standaloneSetup() allows to register one or more controllers without the need to use the full WebApplicationContext.

@Test
public void testHomePage() throws Exception {
    this.mockMvc.perform(get("/"))
            .andExpect(status().isOk())
            .andExpect(view().name("index"))
            .andDo(MockMvcResultHandlers.print());
}

We test the home page. We verify the status and the returned view name. We also print the result.

@Test
public void testMessagePage() throws Exception {
    this.mockMvc.perform(get("/message")).andExpect(status().isOk())
            .andExpect(content().string("Hello there!"));
}

We test the message page. Since it is a RESTful method, we verify the status and the returned string.

$ mvn -q test

We run the tests with mvn -q test.

In this tutorial, we have created tests for Spring MVC with MockMvc.

You might also be interested in these related tutorials: SpringRunner tutorial and Java tutorial.