Mockito - 預期呼叫

Mockito 對可對特定方法進行的呼叫次數進行特殊的檢查。假設 MathApplication 僅應呼叫一次 CalculatorService.serviceUsed() 方法，那麼它應無法多次呼叫 CalculatorService.serviceUsed()。

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

//limit the method call to 1, no less and no more calls are allowed
verify(calcService, times(1)).add(10.0, 20.0);

如下建立 CalculatorService 介面。

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);
}

示例

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 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 的模擬來測試 MathApplication 類。模擬將透過 Mockito 建立。

檔案：MathApplicationTester.java

import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.never;

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);
		
      //add the behavior of calc service to subtract two numbers
      when(calcService.subtract(20.0,10.0)).thenReturn(10.00);
      
      //test the add functionality
      Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0);
      Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0);
      Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0);
      
      //test the subtract functionality
      Assert.assertEquals(mathApplication.subtract(20.0, 10.0),10.0,0.0);
      
      //default call count is 1 
      verify(calcService).subtract(20.0, 10.0);
      
      //check if add function is called three times
      verify(calcService, times(3)).add(10.0, 20.0);
      
      //verify that method was never called on a mock
      verify(calcService, never()).multiply(10.0,20.0);
   }
}

步驟 4 − 執行測試用例

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

現在執行測試執行程式以檢視結果 −

C:\Mockito_WORKSPACE>java TestRunner

驗證輸出。

true