EasyMock.createNiceMock()创建了模拟，并设置模拟的每个方法的默认实现。如果使用EasyMock.createMock()，然后模拟方法调用将抛出断言错误。

语法

calcService = EasyMock.createNiceMock(CalculatorService.class);

示例

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类用来表示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。

在这里，我们已经增加了一个模拟的方法调用，add()通过expect()。但在测试过程中，我们称之为substract()等方法。当创建一个使用EasyMock.createNiceMock()模拟对象，用缺省值缺省实现是可用的。

MathApplicationTester.java

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 substract 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);
   }
}

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

使用javac编译如下类

C:\EasyMock_WORKSPACE>javac MathApplicationTester.java

现在运行测试运行看结果

C:\EasyMock_WORKSPACE>java TestRunner

验证输出

true