EasyMock - 異常處理

EasyMock 允許模擬物件丟擲異常，因此可以測試異常處理。來看一下以下的程式碼片段。

//add the behavior to throw exception

EasyMock.expect(calc Service.add(10.0,20.0)).and Throw(new Runtime Exception("Add operation not implemented"));

在這裡，我們向模擬物件添加了一個異常子句。MathApplication 使用其 add 方法使用 calcService，而每當呼叫 calcService.add() 方法時，模擬物件就會丟擲 RuntimeException。

示例

步驟 1：建立一個名為 CalculatorService 的介面來提供數學函式

檔案：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);
}

步驟 2：建立一個 JAVA 類來表示 MathApplication

檔案：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);
   }
}

步驟 3：測試 MathApplication 類

讓我們透過注入 calculatorService 的模擬物件來測試 MathApplication 類。模擬物件將由 EasyMock 建立。

檔案：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);
   }
}

步驟 4：執行測試用例

在 C:\> EasyMock_WORKSPACE 中建立一個名為 TestRunner 的 java 類檔案來執行測試用例。

檔案：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());
   }
}

步驟 5：驗證結果

使用 javac 編譯器編譯類，如下所示 -

C:\EasyMock_WORKSPACE>javac MathApplicationTester.java

現在，執行測試執行器來檢視結果 -

C:\EasyMock_WORKSPACE>java TestRunner

輸出

驗證輸出。

true