(译) 10-Mockito-异常处理

Mockito 提供了一个模拟抛出异常的功能, 因此可以测试异常处理。查看下面的代码段。

//add the behavior to throw exception
doThrow(new Runtime Exception("divide operation not implemented"))
   .when(calcService).add(10.0,20.0);

在这里, 我们向模拟对象添加了一个异常子句。MathApplication 使用 calcService 的 add 方法, 当调用 calcService. add () 方法时, 该模拟会抛出一个 RuntimeException。

例如

步骤1−创建一个称为 CalculatorService 的接口, 以提供数学函数

文件: CalculatorService. java

/**
 * 计算相关服务
 */
public interface CalculatorService {
    /**
     * 加法
     *
     * @param input1
     * @param input2
     * @return
     */
    public double add(double input1, double input2);

    /**
     * 减法
     *
     * @param input1
     * @param input2
     * @return
     */
    public double subtract(double input1, double input2);

    /**
     * 乘法
     *
     * @param input1
     * @param input2
     * @return
     */
    public double multiply(double input1, double input2);

    /**
     * 除法
     *
     * @param input1
     * @param input2
     * @return
     */
    public double divide(double input1, double input2);
}

步骤2−创建一个 JAVA 类来表示 MathApplication

文件: MathApplication. java

/**
 * 数学应用
 */
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);
    }
}

步骤3−测试 MathApplication 类

让我们测试 MathApplication 类, 通过注入 calculatorService 的Mock。Mock将由 Mockito 创建。

文件: MathApplicationTester. java

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

import java.io.IOException;

import static org.mockito.Mockito.doThrow;

// @RunWith attaches a runner with the test class to initialize the test data
//@RunWith(MockitoRunner.class)
@RunWith(MockitoJUnitRunner.class)
public class MathApplicationTester {

    // @TestSubject annotation is used to identify class which is going to use the mock object
    //@TestSubject
    @InjectMocks
    MathApplication mathApplication = new MathApplication();

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

    @Test//(expected = Exception.class)
    public void testAdd(){
        //add the behavior to throw exception
        doThrow(new RuntimeException("Add operation not implemented")).when(calcService).add(10.0,20.0);

        //test the add functionality
        Assert.assertEquals(mathApplication.add(10.0, 20.0),30.0,0);
    }
}

步骤4−执行测试用例

在C: \ > Mockito_WORKSPACE中创建名为 TestRunner 的 java 类文件以执行测试用例。

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, 如下所示−

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

现在运行TestRunner以查看结果−

C:\Mockito_WORKSPACE>java TestRunner

验证输出。

testAdd(MathApplicationTester): Add operation not implemented
false

翻译自：https://www.tutorialspoint.com/mockito/mockito_exception_handling.htm

注意：

    1.原文章有一处错误，

   @TestSubject会报错

    来自：https://stackoverflow.com/questions/41999135/difference-between-testsubject-and-injectmocks

    2.对测试类，仍然可以使用这个注解 @RunWith(MockitoJUnitRunner.class)

    3.注释掉(expected = RuntimeException.class) 才能实现真正的目的，当然(expected = RuntimeException.class)有它自己的含义，

   参看这篇文章 https://www.mkyong.com/unittest/junit-4-tutorial-2-expected-exception-test/