Easymock 简明教程

EasyMock - Exception Handling

EasyMock 提供了向模拟抛出异常的能力，以便可以测试异常处理。查看以下代码段。

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)).and Throw(new Runtime Exception("Add operation not implemented"));

这里我们向模拟对象添加了一个异常子句。MathApplication 使用 add 方法利用 calcService，并且每当 calcService.add() 方法被调用时，模拟就会抛出一个 RuntimeException。

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

文件: CalculatorService.java

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

文件: MathApplication.java

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

让我们测试 MathApplication 类，并注入一个 calculatorService 模拟。模拟将由 EasyMock 创建。

Let’s test the MathApplication class, by injecting in it a mock of calculatorService. Mock will be created by EasyMock.

文件: MathApplicationTester.java

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 中创建一个名为 TestRunner 的 Java 类文件来执行测试用例。

Create a java class file named TestRunner in C:\> EasyMock_WORKSPACE to execute Test case(s).

文件: TestRunner.java

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

使用以下 javac 编译器编译类：

Compile the classes using javac compiler as follows −

C:\EasyMock_WORKSPACE>javac MathApplicationTester.java

现在运行测试运行器以查看结果 −

Now run the Test Runner to see the result −

C:\EasyMock_WORKSPACE>java TestRunner

Output

验证输出。

Verify the output.

true