Spring Boot - Testing Spring Web Controller with @WebMvcTest - Example

 In this section, we will learn how to test Spring Web Controller with @WebMvcTest. 

1. @WebMvcTest

Instead of bootstrapping the entire application context for every test, @WebMvcTest allows us to initialize only the parts of the Application context that are necessary for our Spring MVC web layer. This allows us to focus on testing the controllers, views, and related components.

Following beans will be scanned while using @WebMvcTest:

  • @Controller
  • @ControllerAdvice
  • @JsonComponent
  • Converter/GenericConverter
  • Filter
  • WebMvcConfigurer
  • HandlerMethodArgumentResolver

Regular @Component, @Service or @Repository beans are not scanned when using this annotation.

This approach not only speeds up the testing process but also ensures a focused and efficient testing environment. 

This approach is also known as "slicing" the application context.

The annotation can be used to test a single controller by passing it as an attribute, for example @WebMvcTest(SomeController.class).

@WebMvcTest(EmployeeController.class)
public class EmployeeControllerTests {

  @Autowired
  private MockMvc mockMvc;

  @MockBean
  private EmployeeRepository employeeRepository;

  @Test
  public void someTest() {
  // Test logic
  }
}

  • MockMvc allows you to prepare and send HTTP requests, also to validate HTTP responses.
  • We use @MockBean in Spring Boot when we want to mock an object that is present in the Spring application context.@MockBean takes care of replacing the bean with what we want to simulate in our test.

2. Creating a spring boot application

First, open the Spring initializr https://start.spring.io

Then, Provide the Group and Artifact name. We have provided Group name com.knf.dev.demo and Artifact webmvctest-example. Here I selected the Maven project - language Java 17 - Spring Boot 3.1.5 , Spring Web, Spring Data JPA, and H2 Database.

Then, click on the Generate button. When we click on the Generate button, it starts packing the project in a .zip(webmvctest-example) file and downloads the project. Then, Extract the Zip file. 

Then, import the project on your favourite IDE.

Final Project Directory:


Complete 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 
   https://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
   <parent>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-parent</artifactId>
      <version>3.1.5</version>
      <relativePath/> <!-- lookup parent from repository -->
   </parent>
   <groupId>com.knf.dev.demo</groupId>
   <artifactId>webmvctest-example</artifactId>
   <version>0.0.1-SNAPSHOT</version>
   <name>webmvctest-example</name>
   <description>Demo project for Spring Boot</description>
   <properties>
      <java.version>17</java.version>
   </properties>
   <dependencies>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-data-jpa</artifactId>
      </dependency>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-web</artifactId>
      </dependency>

      <dependency>
         <groupId>com.h2database</groupId>
         <artifactId>h2</artifactId>
         <scope>runtime</scope>
      </dependency>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-test</artifactId>
         <scope>test</scope>
      </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-test-autoconfigure</artifactId>
        </dependency>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-test-autoconfigure</artifactId>
      </dependency>
      <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-test-autoconfigure</artifactId>
      </dependency>
   </dependencies>

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

</project>

spring-boot-starter-test starter will provide following libraries:

  • JUnit 
  • Spring Test & Spring Boot Test 
  • AssertJ
  • Hamcrest 
  • Mockito 
  • JSONassert 
  • JsonPath 


Create Employee Entity Class

package com.knf.dev.demo.entity;

import jakarta.persistence.*;

@Entity
@Table(name = "employees")
public class Employee {

  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  private long id;

  private String name;

  private String email;

  public Employee() {
  }

  public Employee(long id, String name, String email) {
    this.id = id;
    this.name = name;
    this.email = email;
  }

  public Employee(String name, String email) {
    this.name = name;
    this.email = email;
  }

  public long getId() {
    return id;
  }

  public void setId(long id) {
    this.id = id;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public String getEmail() {
    return email;
  }

  public void setEmail(String email) {
    this.email = email;
  }
}


Create Employee Repository

package com.knf.dev.demo.repository;

import com.knf.dev.demo.entity.Employee;
import org.springframework.data.jpa.repository.JpaRepository;

public interface EmployeeRepository extends JpaRepository<Employee, Long> {
}


Create Employee Controller

package com.knf.dev.demo.controller;

import com.knf.dev.demo.entity.Employee;
import com.knf.dev.demo.repository.EmployeeRepository;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.ArrayList;
import java.util.List;
import java.util.Optional;

@RestController
@RequestMapping("/api/v1")
public class EmployeeController {

    private final EmployeeRepository employeeRepository;


    public EmployeeController(EmployeeRepository employeeRepository) {
        this.employeeRepository = employeeRepository;
    }

    @GetMapping("/employees")
    public ResponseEntity<List<Employee>> getAllEmployees() {

            List<Employee> employees = employeeRepository.findAll();
            return new ResponseEntity<>(employees, HttpStatus.OK);

    }

    @GetMapping("/employees/{id}")
    public ResponseEntity<Employee> getEmployeeById(@PathVariable("id") long id) {

            Optional<Employee> employee = employeeRepository.findById(id);
            return new ResponseEntity<>(employee.get(), HttpStatus.OK);
    }

    @PostMapping("/employees")
    public ResponseEntity<Employee> createEmployee(@RequestBody Employee employee) {

            Employee _employee = employeeRepository.
                    save(new Employee(employee.getName(), employee.getEmail()));
            return new ResponseEntity<>(_employee, HttpStatus.CREATED);

    }

    @PutMapping("/employees/{id}")
    public ResponseEntity<Employee> updateEmployee(@PathVariable("id") long id,
                                                   @RequestBody Employee employee) {

        Optional<Employee> employeeData = employeeRepository.findById(id);

        if (employeeData.isPresent()) {
             Employee _employee = employeeData.get();
            _employee.setName(employee.getName());
            _employee.setEmail(employee.getEmail());

            return new ResponseEntity<>(employeeRepository.save(_employee),
                    HttpStatus.OK);
        } else {
            return new ResponseEntity<>(HttpStatus.NOT_FOUND);
        }
    }

    @DeleteMapping("/employees/{id}")
    public ResponseEntity<HttpStatus> deleteEmployee(@PathVariable("id") long id) {

            employeeRepository.deleteById(id);
            return new ResponseEntity<>(HttpStatus.NO_CONTENT);

    }
}


WebmvctestExampleApplication class

package com.knf.dev.demo;

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

@SpringBootApplication
public class WebmvctestExampleApplication {

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

}


Write Unit test for EmployeeController 

The EmployeeController is a @RestController and thus part of the Web Layer that we want to test.

Create EmployeeControllerTests

When using JUnit 4, this annotation should be used in combination with @RunWith(SpringRunner.class). But for this example  we are using JUnit 5, there’s no need to add the equivalent @ExtendWith(SpringExtension.class).
package com.knf.dev.demo;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.knf.dev.demo.controller.EmployeeController;
import com.knf.dev.demo.entity.Employee;
import com.knf.dev.demo.repository.EmployeeRepository;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
import org.springframework.boot.test.mock.mockito.MockBean;
import org.springframework.http.MediaType;
import org.springframework.test.web.servlet.MockMvc;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Optional;

import static org.mockito.ArgumentMatchers.any;
import static org.mockito.Mockito.doNothing;
import static org.mockito.Mockito.when;
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.*;
import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;

@WebMvcTest(EmployeeController.class)
public class EmployeeControllerTests {

  @Autowired
  private MockMvc mockMvc;
  @Autowired
  private ObjectMapper objectMapper;
  @MockBean
  private EmployeeRepository employeeRepository;

  @Test
  void shouldUpdateEmployee() throws Exception {

    long id = 1L;

    Employee employee = new Employee(1, "Alpha", "alpha@tmail.com");
    Employee updatedEmployee = new Employee(id, "Beta", "alpha@tmail.com");

    when(employeeRepository.findById(id)).thenReturn(Optional.of(employee));
    when(employeeRepository.save(any(Employee.class))).thenReturn(updatedEmployee);

    mockMvc.perform(put("/api/v1/employees/{id}", id).
                    contentType(MediaType.APPLICATION_JSON)
                    .content(objectMapper.writeValueAsString(updatedEmployee)))
            .andExpect(status().isOk())
            .andExpect(jsonPath("$.name").value(updatedEmployee.getName()))
            .andExpect(jsonPath("$.email").value(updatedEmployee.getEmail()))
            .andDo(print());
  }

  @Test
  void shouldReturnListOfEmployees() throws Exception {

    List<Employee> employees = new ArrayList<>(
            Arrays.asList(new Employee(1, "Alpha", "alpha@tmail.com"),
                    new Employee(2, "Beta", "beta@tmail.com"),
                    new Employee(3, "Gama", "gama@tmail.com")));

    when(employeeRepository.findAll()).thenReturn(employees);
    mockMvc.perform(get("/api/v1/employees"))
            .andExpect(status().isOk())
            .andExpect(jsonPath("$.size()").value(employees.size()))
            .andDo(print());
  }

  @Test
  void shouldReturnEmployee() throws Exception {

    long id = 1L;
    Employee employee = new Employee(1, "Alpha", "alpha@tmail.com");

    when(employeeRepository.findById(id)).thenReturn(Optional.of(employee));
    mockMvc.perform(get("/api/v1/employees/{id}", id)).andExpect(status().isOk())
            .andExpect(jsonPath("$.id").value(id))
            .andExpect(jsonPath("$.name").value(employee.getName()))
            .andExpect(jsonPath("$.email").value(employee.getEmail()))
            .andDo(print());
  }

  @Test
  void shouldCreateEmployee() throws Exception {

    Employee employee = new Employee(1, "Alpha", "alpha@tmail.com");

    mockMvc.perform(post("/api/v1/employees").
                    contentType(MediaType.APPLICATION_JSON)
                    .content(objectMapper.writeValueAsString(employee)))
            .andExpect(status().isCreated())
            .andDo(print());
  }

  @Test
  void shouldDeleteEmployee() throws Exception {

    long id = 1L;

    doNothing().when(employeeRepository).deleteById(id);
    mockMvc.perform(delete("/api/v1/employees/{id}", id))
            .andExpect(status().isNoContent())
            .andDo(print());
  }
}

  • MockMvc allows you to prepare and send HTTP requests, also to validate HTTP responses.
  • We use @MockBean in Spring Boot when we want to mock an object that is present in the Spring application context.@MockBean takes care of replacing the bean with what we want to simulate in our test.
  • We can use MockMvc::andExpect in combination with the jsonPath method to test the structure and the content of our response.


3. Run the test

Or you can run the test using following command:

mvn test -Dtest=EmployeeControllerTests

Download the source code - click here!

Popular posts from this blog

Learn Java 8 streams with an example - print odd/even numbers from Array and List

Example 1: Java 8 program to print odd numbers from a List   import java.util.Arrays; import java.util.List; import java.util.stream.Collectors; /*Java 8 Program to find Odd Numbers from a List*/ public class DriverClass { public static void main( String [] args) { List < Integer > numbers = Arrays. asList( 1 , 4 , 8 , 40 , 11 , 22 , 33 , 99 ); List < Integer > oddNumbers = numbers.stream(). filter(o -> o % 2 != 0 ). collect(Collectors.toList()); System.out.println(oddNumbers); } } 1. Initialize List using Arrays.asList() method. Java's built-in Arrays.asList() method converts an array into a list. This method takes an array as an argument and returns a List object. 2.  Java List interface provides stream() method which returns a sequential Stream with list of Integer as its source. 3. The Java stream filter() method allow
Read more

Java Stream API - How to convert List of objects to another List of objects using Java streams?

Image
In this section, we will show you how to convert a List of objects to another List of objects in Java using the Java streams map(). The ‘map’ method maps each element to its corresponding result. Java Stream API   The Java Stream API provides a functional programming approach over the object oriented capabilities of Java. It is used for processing collections of objects. The Stream in Java can be defined as a sequence of elements from a source List, Set or Array. Most of the stream operations return a Stream. This avails engender a chain of stream operations(stream pipe-lining). The streams withal support the aggregate or terminal operations on the elements. for example, finding the sum or maximum element or finding the average etc...Stream operations can either be executed sequentially or parallel. when performed parallelly, it is called a parallel stream.   Stream map() Method   The Java 8 Stream map() is an intermediate operation. It converts Stream<obj1> to Stream<obj2>
Read more

Registration and Login with Spring Boot + Spring Security + Thymeleaf

Image
In this section, we will learn how to create user registration and login using Spring boot, Spring security, Thymeleaf, JPA, and H2DB. The GitHub repository link is provided at the end of this tutorial. You can download the source code. Technologies used: Spring Boot 2.5.5  Spring Data JPA  Spring Security  Thymeleaf  Maven 3+  Java 17  H2 Database   User Interface User Registration Authentication Failed Authentication success Sign out Final Project Structure: Complete 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 https://maven.apache.org/xsd/maven-4.0.0.xsd" > < modelVersion >4.0.0</ modelVersion > < parent > < groupId >org.springframework.boot</ groupId > < artifactId >spring-boot-starter-pare
Read more

Java, Spring Boot Mini Project - Library Management System - Download

Image
Hello everyone, Hope you are doing well. Here, we provide a Library Management System mini-project for beginners, it's free for download. Maybe you can build more on top of this project and create your own product, that's all about you. The source code download link is provided at the end of this post. 1. Benefit of this project You could cover the following technologies and features by learning and debugging this mini project. Java 17 Java Stream Java Lamda Expressions Java Records Functional programming Object-oriented programming var Keyword in Java Generics in Java Java Switch Spring boot 2.6.4 Spring Security Thymeleaf template engine OpenCSV Spring Data JPA Server Side Pagination H2 Database  Bootstrap HTML CSS and more... 2. Objective Of Spring Boot On Library Management System The main objective of this project is to manage the details of the books, author, category, and publisher. Only Admin/Librarian will manage all these activities. Also, they can export the data in
Read more

ReactJS, Spring Boot JWT Authentication Example

Image
In this tutorial, we’ll create a user registration & login example using ReactJS, Spring Boot, Spring Security, and JWT authentication. You could download the source code from our Github repository, the download link is provided at the end of this tutorial. Technologies used Backend Technologies: Java 17 Spring Boot 2.7.0 Spring Security Spring Data JPA JWT H2 Database Frontend Technologies: React 17.0.1 Axios 0.27.2 Redux 4.0.5 Bootstrap 4.5.2 ReactJS - SpringBoot - JWT - Flow Backend Project Directory: Frontend Project Directory: Following is the screenshot of our application - User Registration: User Signin: Profile View: Access Resource: We will build two projects:  1. Backend:   spring-boot-security-jwt 2. Frontend: react-redux-jwt Project 1: spring-boot-security-jwt 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"
Read more

Top 5 Java ORM tools - 2024

Image
  The term ORM refers to object-relational mapping, which uses objects to adapt programming languages to database systems while allowing them to function with SQL and object-oriented programming ideas. Any kind of database management system that can accomplish object mapping to the table in the virtual system is suitable for the implementation of ORM. Java has a wide variety of ORM tools, some of which are mentioned below: 1. Hibernate Hibernate is a lightweight, open-source, non-invasive Java ORM (Object-Relational Mapping) framework that allows developers to create objects that function independently of database software and create persistence logic in any Java or JavaEE application. It offers an abstraction layer, so developers don't have to bother about implementations; Hibernate handles these tasks internally, such as connecting to databases and creating queries to carry out CRUD operations, among other things. Persistence logic development is done with it. Persistence logic r
Read more

Java - Blowfish Encryption and decryption Example

Image
Blowfish is an encryption method developed by Bruce Schneier in 1993 as an alternative to the DES encryption method. It is significantly faster than DES and provides good encryption speed, although no effective cryptanalysis technique has been found to date. It is one of the first secure block ciphers that is not protected by any patents and is therefore freely available for anyone to use. This is a symmetric block cipher algorithm. Block size: 64 bits Key size: variable size from 32 to 448 bits number of subsections: 18 [P-array] number of rounds: 16 number of substitution blocks: 4 [each with 512 records of 32 bits each] develop  Example 1: Encryption and decryption using Blowfish import java.io.UnsupportedEncodingException; import java.nio.charset.Charset; import java.security.InvalidKeyException; import java.security.NoSuchAlgorithmException; import java.util.Base64; import javax.crypto.BadPaddingException; import javax.crypto.Cipher; import javax.crypto.IllegalBlockSizeExc
Read more

Spring boot video streaming example-HTML5

Image
Hello everyone, Today we will learn how to stream MP4 video using Spring Boot and Spring Web Flux.  The Source code download link is provided at the end of this post. New, Quarkus Practice User Interface   Project Structure: G radle(build.gradle) plugins { id 'org.springframework.boot' version '2.5.4' id 'io.spring.dependency-management' version '1.0.11.RELEASE' id 'java' } group = 'com.knf.demo' version = '0.0.1-SNAPSHOT' sourceCompatibility = '11' repositories { mavenCentral() } dependencies { implementation 'org.springframework.boot:spring-boot-starter-webflux' testImplementation 'org.springframework.boot:spring-boot-starter-test' testImplementation 'io.projectreactor:reactor-test' } test { useJUnitPlatform() } Service (VideoStreamingService.java) package  com.knf.demo.service ; import org.springframework.beans.factory.annotation. Autowired ; import org.springframework
Read more

Google Cloud Storage + Spring Boot - File Upload, Download, and Delete

Image
In this section, we will learn  how to  create a simple spring boot application to perform different file operations such as upload, download, list, and delete files from the Google Cloud Storage. 1.  A little bit of Background Google Cloud Storage Cloud Storage is a managed service for storing unstructured data. Store any amount of data and retrieve it as often as you like. More Info - click here! Spring Boot Spring Boot makes it easy to create stand-alone, production-grade Spring-based Applications that you can "just run".  More Info - click here! 2. Create a GCP Project First, Sign into the Google console at  https://console.cloud.google.com . You can create a new project by first selecting the project dropdown in the top left and selecting " New Project ". Next, specify your GCP  Project name  and  Project ID . Then  Click on the " CREATE " button. Copy " Project ID " and keep it for future purposes. 3. Create a Google Cloud Storage bucket Fr
Read more