Mockito – 添加行为

Mockito 使用方法when()向模拟对象添加功能。看看下面的代码片段。

//add the behavior of calc service to add two numbers
when(calcService.add(10.0,20.0)).thenReturn(30.00);

在这里，我们已指示 Mockito 提供将 10 和 20添加到calcService的add方法的行为，并因此返回值 30.00。

此时，Mock 记录了行为并且是一个可以工作的模拟对象。

//add the behavior of calc service to add two numbers
when(calcService.add(10.0,20.0)).thenReturn(30.00);

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。

文件：MathApplicationTester.java

import static org.mockito.Mockito.when;

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

// @RunWith attaches a runner with the test class to initialize the test data
@RunWith(MockitoJUnitRunner.class)
public class MathApplicationTester {
	
   //@InjectMocks annotation is used to create and inject the mock object
   @InjectMocks 
   MathApplication mathApplication = new MathApplication();

   //@Mock annotation is used to create the mock object to be injected
   @Mock
   CalculatorService calcService;

   @Test
   public void testAdd(){
      //add the behavior of calc service to add two numbers
      when(calcService.add(10.0,20.0)).thenReturn(30.00);
		
      //test the add functionality
      Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0);
   }
}

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