mock 抛出异常，新对象似乎无法使用 powermock 工作

Question

我有以下简单的测试用例，使用 powermock 通过模拟 Random 对象的创建来模拟从

ExceptionClass.getRandom

的方法抛出异常。

但是，从测试结果来看，

obj.getRandom()

返回随机值，因此

Assert.assertTrue(obj.getRandom() == 111)

失败，但我认为

obj.getRandom()

应该通过模拟随机创建并抛出异常返回111。

package com.example;

import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.powermock.modules.junit4.PowerMockRunner;

import static org.powermock.api.mockito.PowerMockito.*;

import java.util.Random;

class ExceptionClass {
    public int getRandom() {
        try {
            //Mock the random object using whenNew(Random.class).withNoArguments()
            Random random = new Random();
            //random.nextInt should throw IllegalStateException,so that 111 is returned
            return random.nextInt();
        } catch (Exception e) {
            return 111;
        }
    }
}

@RunWith(PowerMockRunner.class)
public class MockThrowExceptionTest {
    @InjectMocks
    ExceptionClass obj;

    @Test
    public void testGetRandom() throws Exception {
        Random rand = mock(Random.class);
        whenNew(Random.class).withNoArguments().thenReturn(rand);
        when(rand.nextInt()).thenThrow(new IllegalStateException());

        //An exception is thrown in ExceptionClass.getRandom method, so that 111 should be returned,but it is a random value
        Assert.assertTrue(obj.getRandom() == 111);
    }

}

Answer 1

您可以使用

mockito-inline

模拟构造函数。

所需依赖

    <dependency>
        <groupId>org.mockito</groupId>
        <artifactId>mockito-inline</artifactId>
        <version>5.2.0</version>
        <scope>test</scope>
    </dependency>

这是一个使用示例

@Test
public void testGetRandom() throws Exception {
    try (var m = mockConstruction(Random.class,
        (mock, context) -> {
            when(mock.nextInt()).thenReturn(111);
        })) {
        Random r = new Random();
        assertEquals(111, r.nextInt());
    }
}