在本章中，我们将集成JUnit和EasyMock在一起。对于JUnit，请参阅JUnit在线教程。我们使用计算器服务的例子。目的是创建一个数学应用，它使用CalculatorService做加，减，除运算操作。我们将使用EasyMock来模拟虚拟实现CalculatorService。此外，使用注解广泛展示注解支持JUnit和EasyMock。

以下是所采取的步骤。

创建一个接口CalculatorService，其目的是提供各种计算相关的功能。

CalculatorService.java

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);
}

创建一个Java类来表示MathApplication.

MathApplication.java

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);
   }
}

让我们来测试MathApplication类，通过它注入CalculatorService作一个模拟。Mock将由EasyMock创建。

MathApplicationTester.java

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);
   }
}

创建一个Java类在文件夹 C:\ > EasyMock_WORKSPACE 执行测试用例

TestRunner.java

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());
   }
}  	

验证结果

编译使用javac编译如下的类

C:\EasyMock_WORKSPACE>javac CalculatorService.java MathApplication.java MathApplicationTester.java TestRunner.java

现在运行测试运行看结果

C:\EasyMock_WORKSPACE>java TestRunner

验证输出

true