Mean Bean : Testing Java beans and POJOs

Mean bean is a Java open source library used to test bean and POJOs. Mean bean is useful to do unit testing, and get coverage.

Features Offered

a.   Test Java beans and POJOs

b.   Tests equals and hashCode contract compliance

c.    Supports all java primitive types, collections such as Lists, Maps, sets etc.,

You may ask me why do we require this library?

In an Enterprise application, all POJOs, bean and model classes take lot of code. Testing these beans, POJOs is important, Once you are confident enough with your beans, POJOs, model classes, you can straight away go and test your business logic. If you use library like lombok (It provides annotations for getters, setters, toString, equals and hashCode methods), I don't think so we still require this library.  But if your application don't use libraries like lombok, mean bean saves lot of time by unit testing beans and improves unit test code coverage.

I am using following maven dependencies.

<dependencies>
 <dependency>
  <groupId>org.meanbean</groupId>
  <artifactId>meanbean</artifactId>
  <version>2.0.3</version>
 </dependency>

 <dependency>
  <groupId>junit</groupId>
  <artifactId>junit</artifactId>
  <version>4.12</version>
 </dependency>
</dependencies>

Theory is apart; let me explain with an example. For example, I am going to test getter and setter methods of Employee bean.

Employee.java

public class Employee {
 private String name;
 private int id;

 public String getName() {
  return name;
 }

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

 public int getId() {
  return id;
 }

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

 @Override
 public String toString() {
  StringBuilder builder = new StringBuilder();
  builder.append("Employee [name=").append(name).append(", id=")
    .append(id).append("]");
  return builder.toString();
 }

 @Override
 public int hashCode() {
  final int prime = 31;
  int result = 1;
  result = prime * result + id;
  result = prime * result + ((name == null) ? 0 : name.hashCode());
  return result;
 }

 @Override
 public boolean equals(Object obj) {
  if (this == obj)
   return true;
  if (obj == null)
   return false;
  if (getClass() != obj.getClass())
   return false;
  Employee other = (Employee) obj;
  if (id != other.id)
   return false;
  if (name == null) {
   if (other.name != null)
    return false;
  } else if (!name.equals(other.name))
   return false;
  return true;
 }
 

}

BeanTester class provides testBean method to test getters and setter methods of a bean. Following statements are used to test Employee bean setter and getter methods.

BeanTester beanTester = new BeanTester();

beanTester.testBean(Employee.class);

TestBean.java

import org.junit.Test;
import org.meanbean.test.BeanTester;

public class TestBean {

 @Test
 public void testEmployee() {
  BeanTester beanTester = new BeanTester();
  beanTester.testBean(Employee.class);
 }
}

I am going to use EclEmma code coverage tool (You can install it as Eclipse plugin), Following post explains you how to use this tool.

https://self-learning-java-tutorial.blogspot.com/2015/03/eclipse-eclemma-code-coverage-tool.html

After setting up EclEmma plugin, Right click on the file TestBean -> Coverage As -> JUnit Test. By getting the coverage report, you can make sure meanbean library tested getter and setter methods.

Lines in green color are covered while doing unit testing, where as lines in red color are not covered while doing unit testing. Later posts explain you,

How mean bean tests getter and setter methods

Working with custom types

Customize the configuration

How to ignore a properties

How to test equals method
How to test hashCode method

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