Spring Boot MockMVC Example

Automated testing plays a vital role in the software industry. In this article, let us see how to do the testing using MockMvc for a Spring Boot project. To test the web layer, we need MockMvc and by using @AutoConfigureMockMvc, we can write tests that will get injected. SpringBootApplication is an excellent one that adds the following

1. @Configuration
2. @EnableAutoConfiguration
3. @EnableWebMvc
4. @ComponentScan

The application can ordinarily run as a Java application and hence development wise it is easier. Let’s see the concept via a sample project

Example Project

Project Structure:

As it is a maven project, all dependencies are available under 

pom.xml

Dependencies like

1. JDK 1.8
2. Spring version from 2.2.5 onwards
3. Maven 3.2+ and in the case of Gradle, it is Gradle 4+

We should add all the dependencies in pom.xml(in the case of the Maven project)

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.gfg.sample</groupId>
    <artifactId>sampleboot-unit-testing-with-mock-mvc</artifactId>
    <version>1.0-SNAPSHOT</version>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <!-- Mandatory -->
        <version>2.2.5.RELEASE</version>
    </parent>

    <properties>
        <java.version>1.8</java.version>
    </properties>

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

We are using MockMvc to test the web layer. That is we should have a model. a controller, and a view. Let us see the controller file

WelcomeMvcController.java

Each and every method should have either Getmapping or Postmapping

Java

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;

@Controller
public class WelcomeMvcController {
    @Autowired
    private WelcomeService welcomeService;

    @GetMapping(value = "/")
    public String greeting1(String name, Model model) {
        model.addAttribute("welcome", welcomeService.greetingMessage1(name));
        return "welcome-page";
    }

    @GetMapping(value = "/event")
    public String greeting2(String name, Model model) {
        model.addAttribute("welcomeToEvent", welcomeService.greetingMessage2(name));
        return "event-page";
    }
}

Required services are written in the service file

WelcomeService.java

Java

import org.springframework.stereotype.Service;

@Service
public class WelcomeService {
    public String greetingMessage1(String name) {
        return String.format("Welcome , %s to the world of programming!!!", name );
    }

    public String greetingMessage2(String attendee) {
        return String.format("Welldone , %s You are selected to the contest!!!", attendee );
    }
}

SpringBoot Application is run as an ordinary Java application only

WebAppMain.java

Java

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class WebAppMain {
    public static void main(String[] args) {
        SpringApplication.run(WebAppMain.class, args);
    }
}

Now let us start to write the test class that tests the web layer by using MockMvc

WelcomeWebAppTest.java

Java

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import org.springframework.test.web.servlet.MockMvc;
import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
import org.springframework.test.web.servlet.result.MockMvcResultHandlers;
import org.springframework.test.web.servlet.result.MockMvcResultMatchers;

@RunWith(SpringRunner.class)
@SpringBootTest
@AutoConfigureMockMvc
public class WelcomeWebAppTest {
    @Autowired
    private MockMvc mockMvc;

    @Test
    // We have to write out expectations and the
      // expectations need to match with actuals
      // When this is run, it imitates and accesses
      // the web layer and get the output.
    public void testWelcome() throws Exception {
        this.mockMvc.perform(MockMvcRequestBuilders.get("/").param("name", "Geeks"))
                .andExpect(MockMvcResultMatchers.status().isOk())
                .andExpect(MockMvcResultMatchers.model().attribute("welcome",
                        "Welcome , Geeks to the world of programming!!!"))
                .andExpect(MockMvcResultMatchers.view().name("welcome-page"))
                .andDo(MockMvcResultHandlers.print());
    }

    @Test
    public void testWelcomeToEvent() throws Exception {
        this.mockMvc.perform(MockMvcRequestBuilders.get("/event").param("name", "Geeks"))
                .andExpect(MockMvcResultMatchers.status().isOk())
                .andExpect(MockMvcResultMatchers.model().attribute("welcomeToEvent",
                        "Welldone , Geeks You are selected to the contest!!!"))
                .andExpect(MockMvcResultMatchers.view().name("event-page"))
                .andDo(MockMvcResultHandlers.print());
    }

}

Once the project is complete and does not contain any errors, we can run the test file as an ordinary JUNIT application

Console Output:

Once we are getting response 200 means the service is available and the parameters are passed properly and it is producing a positive response. With that response, we are comparing the details by means of

Java

this.mockMvc.perform(MockMvcRequestBuilders.get("/").param("name", "Geeks"))
                .andExpect(MockMvcResultMatchers.status().isOk()) // checking status
                .andExpect(MockMvcResultMatchers.model().attribute("welcome",
                        "Welcome , Geeks to the world of programming!!!")) // sent attribute and its value check
                .andExpect(MockMvcResultMatchers.view().name("welcome-page")) // its view name check
                .andDo(MockMvcResultHandlers.print());

Like this, we can test the web layer in the above-said ways

Conclusion

Automated testing helps to avoid tons of errors and error-free code and helps for good quality software. In the Spring Boot project, we can use MockMvc and can achieve the same.