以下是所采取的步驟。

創建一個接口CalculatorService，其目的是提供各種計算相關的功能。

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);
   public void serviceUsed();
}

創建一個Java類用來表示MathApplication。

MathApplication.java

public class MathApplication {
   private CalculatorService calcService;

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

讓我們來測試MathApplication類，通過它注入CalculatorService作一個模擬。Mock將由EasyMock創建。

MathApplicationTester.java 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);
      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);
   }
}

創建一個Java類在文件夾 C:\ > EasyMock_WORKSPACE 執行測試用例

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());
   }
}  	

驗證結果

使用javac編譯如下類

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

現在運行測試運行看結果

C:\EasyMock_WORKSPACE>java TestRunner

驗證輸出

true