EasyMock - Quick Guide

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EasyMock - Overview

What is Mocking?

Mocking is a way to test the functionality of a class in isolation. Mocking does not require a database connection or properties file read or file server read to test a functionality. Mock objects do the mocking of the real service. A mock object returns a dummy data corresponding to some dummy input passed to it.

EasyMock

EasyMock facilitates creating mock objects seamlessly. It uses Java Reflection in order to create mock objects for a given interface. Mock objects are nothing but proxy for actual implementations. Consider a case of Stock Service which returns the price details of a stock. During development, the actual stock service cannot be used to get real-time data. So we need a dummy implementation of the stock service. EasyMock can do the same very easily as its name suggests.

Benefits of EasyMock

  • No Handwriting − No need to write mock objects on your own.

  • Refactoring Safe − Renaming interface method names or reordering parameters will not break the test code as Mocks are created at runtime.

  • Return value support − Supports return values.

  • Exception support − Supports exceptions.

  • Order check support − Supports check on order of method calls.

  • Annotation support − Supports creating mocks using annotation.

Example

Consider the following code snippet.

package com.tutorialspoint;

import java.util.ArrayList;
import java.util.List;
import org.EasyMock.EasyMock;

public class PortfolioTester {
   public static void main(String[] args){
      //Create a portfolio object which is to be tested		
      Portfolio portfolio = new Portfolio();

      //Creates a list of stocks to be added to the portfolio
      List<Stock> stocks = new ArrayList<Stock>();
      Stock googleStock = new Stock("1","Google", 10);
      Stock microsoftStock = new Stock("2","Microsoft",100);

      stocks.add(googleStock);
      stocks.add(microsoftStock);		

      //Create the mock object of stock service
      StockService stockServiceMock = EasyMock.createMock(StockService.class);

      // mock the behavior of stock service to return the value of various stocks
      EasyMock.expect(stockServiceMock.getPrice(googleStock)).andReturn(50.00);
      EasyMock.expect(stockServiceMock.getPrice(microsoftStock)).andReturn(1000.00);
      EasyMock.replay(stockServiceMock);

      //add stocks to the portfolio
      portfolio.setStocks(stocks);

      //set the stockService to the portfolio
      portfolio.setStockService(stockServiceMock);
      double marketValue = portfolio.getMarketValue();

      //verify the market value to be 
      //10*50.00 + 100* 1000.00 = 500.00 + 100000.00 = 100500
      System.out.println("Market value of the portfolio: "+ marketValue);
   }
}

Let's understand the important concepts of the above program. The complete code is available in the chapter First Application.

  • Portfolio − An object to carry a list of stocks and to get the market value computed using stock prices and stock quantity.

  • Stock − An object to carry the details of a stock such as its id, name, quantity, etc.

  • StockService − A stock service returns the current price of a stock.

  • EasyMock.createMock(...) − EasyMock created a mock of stock service.

  • EasyMock.expect(...).andReturn(...) − Mock implementation of getPrice method of stockService interface. For googleStock, return 50.00 as price.

  • EasyMock.replay(...) − EasyMock prepares the Mock object to be ready so that it can be used for testing.

  • portfolio.setStocks(...) − The portfolio now contains a list of two stocks.

  • portfolio.setStockService(...) − Assigns the stockService Mock object to the portfolio.

  • portfolio.getMarketValue() − The portfolio returns the market value based on its stocks using the mock stock service.

EasyMock - Environment Setup

This chapter will guide you on how to prepare a development environment to start your work with EasyMock. It will also teach you how to set up JDK on your machine before you set up EasyMock Testing Framework −

Setup Java Development Kit (JDK)

You can download the latest version of SDK from Oracle's Java site − Java SE Downloads. You will find instructions for installing JDK in downloaded files, follow the given instructions to install and configure the setup. Finally set PATH and JAVA_HOME environment variables to refer to the directory that contains java and javac, typically java_install_dir/bin and java_install_dir respectively.

If you are running Windows and have installed the JDK in C:\jdk-24, you would have to put the following line in your C:\autoexec.bat file.

set PATH=C:\jdk-24;%PATH% 
set JAVA_HOME=C:\jdk-24

Alternatively, on Windows NT/2000/XP, you will have to right-click on My Computer, select Properties → Advanced → Environment Variables. Then, you will have to update the PATH value and click the OK button.

On Unix (Solaris, Linux, etc.), if the SDK is installed in /usr/local/jdk-24 and you use the C shell, you will have to put the following into your .cshrc file.

setenv PATH /usr/local/jdk-24/bin:$PATH 
setenv JAVA_HOME /usr/local/jdk-24

Alternatively, if you use an Integrated Development Environment (IDE) like Borland JBuilder, Eclipse, IntelliJ IDEA, or Sun ONE Studio, you will have to compile and run a simple program to confirm that the IDE knows where you have installed Java. Otherwise, you will have to carry out a proper setup as given in the document of the IDE.

Popular Java Editors

To write your Java programs, you need a text editor. There are many sophisticated IDEs available in the market. But for now, you can consider one of the following −

  • Notepad − On Windows machine, you can use any simple text editor like Notepad (Recommended for this tutorial), TextPad.

  • Netbeans − It is a Java IDE that is open-source and free, which can be downloaded from www.netbeans.org/index.html.

  • Eclipse − It is also a Java IDE developed by the eclipse open-source community and can be downloaded from www.eclipse.org.

Step 3: Install EasyMock Library

Download the latest version of EasyMock from https://easymock.org/ and unzip its contents to a folder from where the required libraries can be linked to your Java program. Let us assume the files are collected in a folder on C drive.

Add the complete path of the required jars as shown below to the CLASSPATH.

Sr.No. Platform & Description
1

Windows

Append the following strings to the end of the user variable

CLASSPATH −

C:\easymock\easymock-5.6.0.jar;
2

Linux

Export CLASSPATH = $CLASSPATH:

/usr/share/easymock\easymock-5.6.0.tar:

Step 4: Download JUnit Archive

Download the latest version of JUnit jar file from Github. Save the folder at the location C:\>Junit.

OS Archive name
Windows junit4.13.2.jar, hamcrest-core-1.3.jar
Linux junit4.13.2.jar, hamcrest-core-1.3.jar

Step 5: Set JUnit Environment

Set the JUNIT_HOME environment variable to point to the base directory location where JUnit jars are stored on your machine. The following table shows how to set this environment variable on different operating systems, assuming we've stored junit4.13.2.jar and hamcrest-core-1.3.jar at C:\>Junit.

OS Output
Windows Set the environment variable JUNIT_HOME to C:\JUNIT
Linux export JUNIT_HOME=/usr/local/JUNIT

Step 6: Set CLASSPATH Variable

Set the CLASSPATH environment variable to point to the JUNIT jar location. The following table shows how it is done on different operating systems.

OS Output
Windows Set the environment variable CLASSPATH to %CLASSPATH%;%JUNIT_HOME%\ junit4.13.2.jar;%JUNIT_HOME%\hamcrest-core-1.3.jar;.
Linux Export CLASSPATH=$CLASSPATH:$JUNIT_HOME/ junit4.13.2.jar:$JUNIT_HOME/hamcrest-core-1.3.jar:.

EasyMock - First Application

Before going into the details of the EasyMock Framework, lets see an application in action. In this example, we've created a mock of Stock Service to get the dummy price of some stocks and unit tested a java class named Portfolio.

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

Example - Usage of Mock

Step 1: Create a JAVA class to represent the Stock.

Stock.java

package com.tutorialspoint;

public class Stock {
   private String stockId;
   private String name;	
   private int quantity;

   public Stock(String stockId, String name, int quantity){
      this.stockId = stockId;
      this.name = name;		
      this.quantity = quantity;		
   }
   public String getStockId() {
      return stockId;
   }
   public void setStockId(String stockId) {
      this.stockId = stockId;
   }
   public int getQuantity() {
      return quantity;
   }
   public String getTicker() {
      return name;
   }
}

Step 2: Create an interface StockService to get the price of a stock.

StockService.java

package com.tutorialspoint;

public interface StockService {
   public double getPrice(Stock stock);
}

Step 3: Create a class Portfolio to represent the portfolio of any client.

Portfolio.java

package com.tutorialspoint;

import java.util.List;

public class Portfolio {
   private StockService stockService;
   private List<Stock> stocks;

   public StockService getStockService() {
      return stockService;
   }
   public void setStockService(StockService stockService) {
      this.stockService = stockService;
   }
   public List<Stock> getStocks() {
      return stocks;
   }
   public void setStocks(List<Stock> stocks) {
      this.stocks = stocks;
   }
   public double getMarketValue(){
      double marketValue = 0.0;
      for(Stock stock:stocks){
         marketValue += stockService.getPrice(stock) * stock.getQuantity();
      }
      return marketValue;
   }
}

Step 4: Test the Portfolio class.

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

PortfolioTester.java

package com.tutorialspoint;

import java.util.ArrayList;
import java.util.List;
import org.easymock.EasyMock;

public class PortfolioTester {
   Portfolio portfolio;	
   StockService stockService;

   public static void main(String[] args){
      PortfolioTester tester = new PortfolioTester();
      tester.setUp();
      System.out.println(tester.testMarketValue()?"pass":"fail");
   }
   public void setUp(){
      //Create a portfolio object which is to be tested		
      portfolio = new Portfolio();		
      
      //Create the mock object of stock service
      stockService = EasyMock.createMock(StockService.class);		
      
      //set the stockService to the portfolio
      portfolio.setStockService(stockService);
   }
   public boolean testMarketValue(){
      //Creates a list of stocks to be added to the portfolio
      List<Stock> stocks = new ArrayList<Stock>();
      Stock googleStock = new Stock("1","Google", 10);
      Stock microsoftStock = new Stock("2","Microsoft",100);	
      
      stocks.add(googleStock);
      stocks.add(microsoftStock);

      //add stocks to the portfolio
      portfolio.setStocks(stocks);

      // mock the behavior of stock service to return the value of various stocks
      EasyMock.expect(stockService.getPrice(googleStock)).andReturn(50.00);
      EasyMock.expect(stockService.getPrice(microsoftStock)).andReturn(1000.00);		

      // activate the mock
      EasyMock.replay(stockService);		

      double marketValue = portfolio.getMarketValue();		
      return marketValue == 100500.0;
   }
}

Output

Run the PortfolioTester and verify the output.

pass

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.

EasyMock - Adding Behavior

EasyMock adds a functionality to a mock object using the methods expect() and expectLassCall(). Take a look at the following code snippet.

//add the behavior of calc service to add two numbers
EasyMock.expect(calcService.add(10.0,20.0)).andReturn(30.00);

Here we've instructed EasyMock to give a behavior of adding 10 and 20 to the add method of calcService and as a result, to return the value of 30.00.

At this point of time, Mock simply recorded the behavior but it is not working as a mock object. After calling replay, it works as expected.

//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);

Example without EasyMock.Replay()

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 the 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: Execute test cases.

Create a java class file named TestRunner to execute the 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.

testAdd(com.tutorialspoint.MathApplicationTester): expected:<0.0> but was:<30.0>
false

Example with EasyMock.Replay()

Update the MathApplicationTester class to use the replay() method.

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.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);
   }
}

Output

Run the TestRunner and verify the output.

true

EasyMock - Verifying Behavior

EasyMock can ensure whether a mock is being used or not. It is done using the verify() method. Take a look at the following code snippet.

//activate the mock
EasyMock.replay(calcService);

//test the add functionality
Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0);

//verify call to calcService is made or not
EasyMock.verify(calcService);

Example without EasyMock.Verify()

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);
      return 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.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);

      //verify call to calcService is made or not
      //EasyMock.verify(calcService);
   }
}

Step 4: Execute 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

Example with EasyMock.Verify()

Update the MathApplication class to use the verify() method.

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);

      //verify call to calcService is made or not
      EasyMock.verify(calcService);
   }
}

Output

Run the TestRunner and verify the output.

testAdd(com.tutorialspoint.MathApplicationTester): 
  Expectation failure on verify:
    EasyMock for field com.tutorialspoint.MathApplicationTester.calcService -> CalculatorService.add(10.0 (double), 20.0 (double)): expected: 1, actual: 0
false

EasyMock - Expecting Calls

EasyMock provides a special check on the number of calls that can be made on a particular method. Suppose MathApplication should call the CalculatorService.serviceUsed() method only once, then it should not be able to call CalculatorService.serviceUsed() more than once.

//add the behavior of calc service to add two numbers and serviceUsed.
EasyMock.expect(calcService.add(10.0,20.0)).andReturn(30.00);
calcService.serviceUsed();

//limit the method call to 1, no less and no more calls are allowed
EasyMock.expectLastCall().times(1);

Create CalculatorService interface as follows.

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);
   public void serviceUsed();
}

Example with calcService.serviceUsed() called once

Step 1: 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){		
      calcService.serviceUsed();
      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.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);
      calcService.serviceUsed();
      EasyMock.expectLastCall().times(1);
      
      //activate the mock
      EasyMock.replay(calcService);	
		
      //test the add functionality
      Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0);

      //verify call to calcService is made or not
      EasyMock.verify(calcService);
   }
}

Step 4: Execute test cases.

Create a java class file named TestRunner in 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

Example with calcService.serviceUsed() Called Twice

Update the MathApplication class to call serviceUsed() method twice

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){		
      calcService.serviceUsed();
      calcService.serviceUsed();
      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);
   }
}

Output

Run the TestRunner and verify the output.

testAdd(com.tutorialspoint.MathApplicationTester): 
  Unexpected method call EasyMock for field com.tutorialspoint.MathApplicationTester.calcService -> CalculatorService.serviceUsed():
    EasyMock for field com.tutorialspoint.MathApplicationTester.calcService -> CalculatorService.add(10.0 (double), 20.0 (double)): expected: 1, actual: 0
    EasyMock for field com.tutorialspoint.MathApplicationTester.calcService -> CalculatorService.serviceUsed(): expected: 1, actual: 2
false

Example without Calling calcService.serviceUsed()

Update the MathApplication class to remove call to serviceUsed() method.

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);
   }
}

Output

Run the TestRunner and verify the output.

testAdd(com.tutorialspoint.MathApplicationTester): 
  Expectation failure on verify:
    EasyMock for field com.tutorialspoint.MathApplicationTester.calcService -> CalculatorService.serviceUsed(): expected: 1, actual: 0
false

EasyMock - Varying Calls

EasyMock provides the following additional methods to vary the expected call counts.

  • times (int min, int max) − expects between min and max calls.

  • atLeastOnce () − expects at least one call.

  • anyTimes () − expects an unrestricted number of calls.

Example with times (min,max)

Step 1: Create an interface 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);
   public void serviceUsed();
}

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){
      calcService.serviceUsed();
      calcService.serviceUsed();
      calcService.serviceUsed();   
      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);
      calcService.serviceUsed();
      EasyMock.expectLastCall().times(1,3);
      
      //activate the mock
      EasyMock.replay(calcService);	
		
      //test the add functionality
      Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0);

      //verify call to calcService is made or not
      EasyMock.verify(calcService);
   }
}

Step 4: Execute 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

Example with atLeastOnce

Update the MathApplicationTester class to use atLeastOnce() method.

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

      //verify call to calcService is made or not
      EasyMock.verify(calcService);
   }
}

Output

Run the TestRunner and verify the output.

true

Example with anyTimes

Update the MathApplicationTester class to use anyTimes() method.

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

      //verify call to calcService is made or not
      EasyMock.verify(calcService);
   }
}

Output

Run the TestRunner and verify the output.

true

EasyMock - Exception Handling

EasyMock provides the capability to a mock to throw exceptions, so exception handling can be tested. Take a look at the following code snippet.

//add the behavior to throw exception
EasyMock.expect(calc Service.add(10.0,20.0))
.andThrow(new Runtime Exception("Add operation not implemented"));

Here we've added an exception clause to a mock object. MathApplication makes use of calcService using its add method and the mock throws a RuntimeException whenever calcService.add() method is invoked.

Example

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.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(expected = RuntimeException.class)
   public void testAdd(){
      //add the behavior to throw exception
      EasyMock.expect(calcService.add(10.0,20.0)).andThrow(
         new RuntimeException("Add operation not implemented")
      );
      //activate the mock
      EasyMock.replay(calcService);			
      
      //test the add functionality
      Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0);
      
      //verify call to calcService is made or not
      EasyMock.verify(calcService);
   }
}

Step 4: Execute 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

EasyMock - createMock() Method

So far, we've used annotations to create mocks. EasyMock provides various methods to create mock objects. EasyMock.createMock() creates mocks without bothering about the order of method calls that the mock is going to make in due course of its action.

Syntax

calcService = EasyMock.createMock(CalculatorService.class);

Example

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.

Here we've added two mock method calls, add() and subtract(), to the mock object via expect(). However during testing, we've called subtract() before calling add(). When we create a mock object using EasyMock.createMock(), the order of execution of the method does not matter.

MathApplicationTester.java

package com.tutorialspoint;

import org.easymock.EasyMock;
import org.easymock.EasyMockRunner;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;

@RunWith(EasyMockRunner.class)
public class MathApplicationTester {
   private MathApplication mathApplication;
   private CalculatorService calcService;
   
   @Before
   public void setUp(){
      mathApplication = new MathApplication();
      calcService = EasyMock.createMock(CalculatorService.class);
      mathApplication.setCalculatorService(calcService);
   }
   @Test
   public void testAddAndSubtract(){
      //add the behavior to add numbers
      EasyMock.expect(calcService.add(20.0,10.0)).andReturn(30.0);
      
      //subtract the behavior to subtract numbers
      EasyMock.expect(calcService.subtract(20.0,10.0)).andReturn(10.0);
      
      //activate the mock
      EasyMock.replay(calcService);	
	
      //test the subtract functionality
      Assert.assertEquals(mathApplication.subtract(20.0, 10.0),10.0,0);
      
      //test the add functionality
      Assert.assertEquals(mathApplication.add(20.0, 10.0),30.0,0);
      
      //verify call to calcService is made or not
      EasyMock.verify(calcService);
   }
}

Step 4: Execute 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

EasyMock - createStrictMock() Method

EasyMock.createStrictMock() creates a mock and also takes care of the order of method calls that the mock is going to make in due course of its action.

Syntax

calcService = EasyMock.createStrictMock(CalculatorService.class);

Example

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.

Here we've added two mock method calls, add() and subtract(), to the mock object via expect(). However during testing, we've called subtract() before calling add(). When we create a mock object using EasyMock.createStrictMock(), the order of execution of the method does matter.

MathApplicationTester.java

package com.tutorialspoint;

import org.easymock.EasyMock;
import org.easymock.EasyMockRunner;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;

@RunWith(EasyMockRunner.class)
public class MathApplicationTester {
   private MathApplication mathApplication;
   private CalculatorService calcService;
   
   @Before
   public void setUp(){
      mathApplication = new MathApplication();
      calcService = EasyMock.createStrictMock(CalculatorService.class);
      mathApplication.setCalculatorService(calcService);
   }
   @Test
   public void testAddAndSubtract(){
      //add the behavior to add numbers
      EasyMock.expect(calcService.add(20.0,10.0)).andReturn(30.0);
      
      //subtract the behavior to subtract numbers
      EasyMock.expect(calcService.subtract(20.0,10.0)).andReturn(10.0);
      
      //activate the mock
      EasyMock.replay(calcService);	
	
      //test the subtract functionality
      Assert.assertEquals(mathApplication.subtract(20.0, 10.0),10.0,0);
      
      //test the add functionality
      Assert.assertEquals(mathApplication.add(20.0, 10.0),30.0,0);
      
      //verify call to calcService is made or not
      EasyMock.verify(calcService);
   }
}

Step 4: Execute 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.

testAddAndSubtract(com.tutorialspoint.MathApplicationTester): 
  Unexpected method call EasyMock for interface com.tutorialspoint.CalculatorService -> CalculatorService.subtract(20.0 (double), 10.0 (double)):
    EasyMock for interface com.tutorialspoint.CalculatorService -> CalculatorService.add(20.0 (double), 10.0 (double)): expected: 1, actual: 0
false

EasyMock - createNiceMock() Method

EasyMock.createNiceMock() creates a mock and sets the default implementation of each method of the mock. If EasyMock.createMock() is used, then invoking the mock method throws assertion error.

Syntax

calcService = EasyMock.createNiceMock(CalculatorService.class);

Example

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.

Here we've added one mock method call, add(), via expect(). However during testing, we've called subtract() and other methods as well. When we create a mock object using EasyMock.createNiceMock(), the default implementation with default values are available.

MathApplicationTester.java

package com.tutorialspoint;

import org.easymock.EasyMock;
import org.easymock.EasyMockRunner;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;

@RunWith(EasyMockRunner.class)
public class MathApplicationTester {
   private MathApplication mathApplication;
   private CalculatorService calcService;

   @Before
   public void setUp(){
      mathApplication = new MathApplication();
      calcService = EasyMock.createNiceMock(CalculatorService.class);
      mathApplication.setCalculatorService(calcService);
   }
   @Test
   public void testCalcService(){
      //add the behavior to add numbers
      EasyMock.expect(calcService.add(20.0,10.0)).andReturn(30.0);
      
      //activate the mock
      EasyMock.replay(calcService);	
      
      //test the add functionality
      Assert.assertEquals(mathApplication.add(20.0, 10.0),30.0,0);
      
      //test the subtract functionality
      Assert.assertEquals(mathApplication.subtract(20.0, 10.0),0.0,0);
      
      //test the multiply functionality
      Assert.assertEquals(mathApplication.divide(20.0, 10.0),0.0,0);		
      
      //test the divide functionality
      Assert.assertEquals(mathApplication.multiply(20.0, 10.0),0.0,0);

      //verify call to calcService is made or not
      EasyMock.verify(calcService);
   }
}

Step 4: Execute 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
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