异常处理（ Exception Handling）

EasyMock为mock提供了抛出异常的功能，因此可以测试异常处理。 请查看以下代码段。

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

这里我们为模拟对象添加了一个exception子句。 MathApplication使用其add方法使用calcService，并且每当调用calcService.add（）方法时，mock都会抛出RuntimeException。

例子 (Example)

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

File: 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);
}

Step 2: Create a JAVA class to represent MathApplication

File: 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);
   }
}

Step 3: Test the MathApplication class

让我们通过在其中注入一个模拟的calculatorService来测试MathApplication类。 Mock将由EasyMock创建。

File: 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.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

在C:\》 EasyMock_WORKSPACE创建一个名为TestRunner的java类文件，以执行测试用例。

File: 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());
   }
}  	

Step 5: Verify the Result

使用javac编译器编译类，如下所示:

C:\EasyMock_WORKSPACE>javac MathApplicationTester.java

现在运行Test Runner来查看结果:

C:\EasyMock_WORKSPACE>java TestRunner

验证输出。

true