Mockito – 间谍活动

Mockito 提供了在真实物体上创建间谍的选项。当 spy 被调用时，则调用真实对象的实际方法。

句法

//create a spy on actual object
calcService = spy(calculator);

//perform operation on real object
//test the add functionality
Assert.assertEquals(mathApplication.add(20.0, 10.0),30.0,0);

例子

Step 1 – 创建一个名为 CalculatorService 的接口来提供数学函数

文件：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);
}

第 2 步 – 创建一个 JAVA 类来表示 MathApplication

文件：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);
   }
}

第 3 步 – 测试 MathApplication 类

让我们测试 MathApplication 类，通过在其中注入一个计算器服务的模拟。Mock 将由 Mockito 创建。

在这里，我们通过 when() 添加了一个模拟方法调用 add() 到模拟对象。但是在测试过程中，我们在调用 add() 之前调用了消减()。当我们使用 Mockito.createStrictMock() 创建模拟对象时，方法的执行顺序很重要。

文件：MathApplicationTester.java

import static org.mockito.Mockito.spy;

import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.runners.MockitoJUnitRunner;

// @RunWith attaches a runner with the test class to initialize the test data
@RunWith(MockitoJUnitRunner.class)
public class MathApplicationTester {
	
   private MathApplication mathApplication;
   private CalculatorService calcService;

   @Before
   public void setUp(){
      mathApplication = new MathApplication();
      Calculator calculator = new Calculator();
      calcService = spy(calculator);
      mathApplication.setCalculatorService(calcService);	     
   }

   @Test
   public void testAdd(){

      //perform operation on real object
      //test the add functionality
      Assert.assertEquals(mathApplication.add(20.0, 10.0),30.0,0);
   }

   class Calculator implements CalculatorService {
      @Override
      public double add(double input1, double input2) {
         return input1 + input2;
      }

      @Override
      public double subtract(double input1, double input2) {
         throw new UnsupportedOperationException("Method not implemented yet!");
      }

      @Override
      public double multiply(double input1, double input2) {
         throw new UnsupportedOperationException("Method not implemented yet!");
      }

      @Override
      public double divide(double input1, double input2) {
         throw new UnsupportedOperationException("Method not implemented yet!");
      }
   }
}

第 4 步 – 执行测试用例

在C:\> Mockito_WORKSPACE 中创建一个名为 TestRunner 的 java 类文件来执行测试用例。

文件：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());
   }
}  	

步骤 5 – 验证结果

使用javac编译器编译类如下 –

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

现在运行 Test Runner 以查看结果 –

C:\Mockito_WORKSPACE>java TestRunner

验证输出。

true