EasyMock - JUnit Integration

In this chapter, we'll learn how to integrate JUnit and EasyMock together. Here we will create a Math Application which uses CalculatorService to perform basic mathematical operations such as addition, subtraction, multiply, and division. We'll use EasyMock to mock the dummy implementation of CalculatorService. In addition, we've made extensive use of annotations to showcase their compatibility with both JUnit and EasyMock.

Example - JUnit Integration with EasyMock

The process is discussed below in a step-by-step manner.

Step 1: Create an interface called CalculatorService to provide mathematical functions.

CalculatorService.java

package com.tutorialspoint;

public interface CalculatorService {
   public double add(double input1, double input2);
   public double subtract(double input1, double input2);
   public double multiply(double input1, double input2);
   public double divide(double input1, double input2);
}

Step 2: Create a JAVA class to represent MathApplication.

MathApplication.java

package com.tutorialspoint;

public class MathApplication {
   private CalculatorService calcService;

   public void setCalculatorService(CalculatorService calcService){
      this.calcService = calcService;
   }
   public double add(double input1, double input2){
      return calcService.add(input1, input2);
   }
   public double subtract(double input1, double input2){
      return calcService.subtract(input1, input2);
   }
   public double multiply(double input1, double input2){
      return calcService.multiply(input1, input2);
   }
   public double divide(double input1, double input2){
      return calcService.divide(input1, input2);
   }
}

Step 3: Test the MathApplication class.

Let's test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by EasyMock.

MathApplicationTester.java

package com.tutorialspoint;

import org.easymock.EasyMock;
import org.easymock.EasyMockRunner;
import org.easymock.Mock;
import org.easymock.TestSubject;

import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;

// @RunWith attaches a runner with the test class to initialize the test data
@RunWith(EasyMockRunner.class)
public class MathApplicationTester {
   // @TestSubject annotation is used to identify class which is going to use the mock object
   @TestSubject
   MathApplication mathApplication = new MathApplication();

   //@Mock annotation is used to create the mock object to be injected
   @Mock
   CalculatorService calcService;

   @Test
   public void testAdd(){
      //add the behavior of calc service to add two numbers
      EasyMock.expect(calcService.add(10.0,20.0)).andReturn(30.00);

      //activate the mock
      EasyMock.replay(calcService);	
		
      //test the add functionality
      Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0);
   }
}

Step 4: Create a class to execute to test cases.

Create a java class file named TestRunner to execute Test case(s).

TestRunner.java

package com.tutorialspoint;

import org.junit.runner.JUnitCore;
import org.junit.runner.Result;
import org.junit.runner.notification.Failure;

public class TestRunner {
   public static void main(String[] args) {
      Result result = JUnitCore.runClasses(MathApplicationTester.class);
      for (Failure failure : result.getFailures()) {
         System.out.println(failure.toString());
      }
      System.out.println(result.wasSuccessful());
   }
}  	

Output

Run the TestRunner and verify the output.

true

To learn more about JUnit, please refer to JUnit Tutorial.