Baeldung Pro comes with both absolutely No-Ads as well as finally with Dark Mode, for a clean learning experience:
Once the early-adopter seats are all used, the price will go up and stay at $33/year.
Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.
Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.
To learn more about Java features on Azure Container Apps, visit the documentation page.
You can also ask questions and leave feedback on the Azure Container Apps GitHub page.
Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.
Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.
To learn more about Java features on Azure Container Apps, you can get started over on the documentation page.
And, you can also ask questions and leave feedback on the Azure Container Apps GitHub page.
Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.
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Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.
Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.
With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.
Try a 14-Day Free Trial of Orkes Conductor today.
Mocking is an essential part of unit testing, and the Mockito library makes it easy to write clean and intuitive unit tests for your Java code.
Get started with mocking and improve your application tests using our Mockito guide:
Handling concurrency in an application can be a tricky process with many potential pitfalls. A solid grasp of the fundamentals will go a long way to help minimize these issues.
Get started with understanding multi-threaded applications with our Java Concurrency guide:
Spring 5 added support for reactive programming with the Spring WebFlux module, which has been improved upon ever since. Get started with the Reactor project basics and reactive programming in Spring Boot:
Since its introduction in Java 8, the Stream API has become a staple of Java development. The basic operations like iterating, filtering, mapping sequences of elements are deceptively simple to use.
But these can also be overused and fall into some common pitfalls.
To get a better understanding on how Streams work and how to combine them with other language features, check out our guide to Java Streams:
Explore Spring Boot 3 and Spring 6 in-depth through building a full REST API with the framework:
Yes, Spring Security can be complex, from the more advanced functionality within the Core to the deep OAuth support in the framework.
I built the security material as two full courses - Core and OAuth, to get practical with these more complex scenarios. We explore when and how to use each feature and code through it on the backing project.
You can explore the course here:
All Access is finally out, with all of my Spring courses. Learn JUnit is out as well, and Learn Maven is coming fast. And, of course, quite a bit more affordable. Finally.
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Spring Data JPA is a great way to handle the complexity of JPA with the powerful simplicity of Spring Boot.
Get started with Spring Data JPA through the guided reference course:
End-to-end testing is a very useful method to make sure that your application works as intended. This highlights issues in the overall functionality of the software, that the unit and integration test stages may miss.
Playwright is an easy-to-use, but powerful tool that automates end-to-end testing, and supports all modern browsers and platforms.
When coupled with LambdaTest (an AI-powered cloud-based test execution platform) it can be further scaled to run the Playwright scripts in parallel across 3000+ browser and device combinations:
Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:
Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:
1. Introduction
ReflectionTestUtils is a part of the Spring Test Context framework. It’s a collection for reflection-based utility methods used in a unit, and integration testing scenarios to set the non-public fields, invoke non-public methods, and inject dependencies.
In this tutorial, we’ll learn how to use ReflectionTestUtils in unit testing by going through several examples.
2. Maven Dependencies
We’ll start by adding the latest versions of all the necessary dependencies to our pom.xml:
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>5.1.2.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>5.1.2.RELEASE</version>
<scope>test</scope>
</dependency>The latest spring-context and spring-test dependencies can be downloaded from the Maven Central repository.
3. Using ReflectionTestUtils to Set a Value of a Non-Public Field
Suppose we need to use an instance of a class having a private field, without a public setter method in our unit test.
We’ll start by creating it:
public class Employee {
private Integer id;
private String name;
// standard getters/setters
}Normally we can’t access the private field id to assign a value for testing because there isn’t a public setter method for it.
So we’ll use the ReflectionTestUtils.setField method to assign a value to the private member id:
@Test
public void whenNonPublicField_thenReflectionTestUtilsSetField() {
Employee employee = new Employee();
ReflectionTestUtils.setField(employee, "id", 1);
assertTrue(employee.getId().equals(1));
}4. Using ReflectionTestUtils to Invoke a Non-Public Method
Now let’s imagine that we have a private method, employeeToString, in the Employee class:
private String employeeToString(){
return "id: " + getId() + "; name: " + getName();
}We can write a unit test for the employeeToString method as below, even though it doesn’t have any access from outside of an Employee class:
@Test
public void whenNonPublicMethod_thenReflectionTestUtilsInvokeMethod() {
Employee employee = new Employee();
ReflectionTestUtils.setField(employee, "id", 1);
employee.setName("Smith, John");
assertTrue(ReflectionTestUtils.invokeMethod(employee, "employeeToString")
.equals("id: 1; name: Smith, John"));
}5. Using ReflectionTestUtils to Inject Dependencies
Let’s say we want to write a unit test for the following Spring component having a private field with the @Autowired annotation:
@Component
public class EmployeeService {
@Autowired
private HRService hrService;
public String findEmployeeStatus(Integer employeeId) {
return "Employee " + employeeId + " status: " + hrService.getEmployeeStatus(employeeId);
}
}Now we can implement the HRService component as below:
@Component
public class HRService {
public String getEmployeeStatus(Integer employeeId) {
return "Inactive";
}
}Furthermore, we’ll create a mock implementation for the HRService class by using Mockito. We’ll inject this mock into the EmployeeService instance, and we’ll use it in our unit test:
HRService hrService = mock(HRService.class);
when(hrService.getEmployeeStatus(employee.getId())).thenReturn("Active");Because hrService is a private field without a public setter, we’ll use the ReflectionTestUtils.setField method to inject the mock we created above into this private field:
EmployeeService employeeService = new EmployeeService();
ReflectionTestUtils.setField(employeeService, "hrService", hrService);Finally, our unit test will look similar to this:
@Test
public void whenInjectingMockOfDependency_thenReflectionTestUtilsSetField() {
Employee employee = new Employee();
ReflectionTestUtils.setField(employee, "id", 1);
employee.setName("Smith, John");
HRService hrService = mock(HRService.class);
when(hrService.getEmployeeStatus(employee.getId())).thenReturn("Active");
EmployeeService employeeService = new EmployeeService();
// Inject mock into the private field
ReflectionTestUtils.setField(employeeService, "hrService", hrService);
assertEquals(
"Employee " + employee.getId() + " status: Active",
employeeService.findEmployeeStatus(employee.getId()));
}We should note that this technique is a workaround for the fact that we’re using field injection in our bean class. If we switched to constructor injection, then this approach wouldn’t be necessary.
6. Conclusion
In this article, we demonstrated how to use ReflectionTestUtils in unit testing by going through several examples.
The code backing this article is available on GitHub. Once you're logged in as a Baeldung Pro Member, start learning and coding on the project.
