在没有 PowerMockito JUnit5 的情况下创建新实例时进行模拟

如何解决在没有 PowerMockito JUnit5 的情况下创建新实例时进行模拟

JUnit5 不支持 PowerMockRunner，因此当您从 JUnit4 迁移到 JUnit5 时，以下代码将不起作用。

例如。 您尝试注入模拟的代码

import javax.naming.InvalidNameException;

public class Main {

    public static void main(String[] args) {
        Main main = new Main();
        main.publish();
    }

    public void publish() {
        try {
            Sample s = new Sample();
            s.invoke("Hello");
        } catch (InvalidNameException e) {
            throw new ServiceFailureException(e.getMessage());
        }
    }

} 

在这里，您尝试测试发布方法，在该方法中您模拟 Sample 实例以响应不同的响应。 在 JUnit4 中，您可以使用 PowerMockito 来实现这一点。

import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mockito;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

import javax.naming.InvalidNameException;

@RunWith(PowerMockRunner.class)
@PrepareForTest({Main.class})
public class MainTest {

    @Test
    public void testPublishSuccess() {
        Main m = new Main();
        Assert.assertEquals("Expected result not found","success",m.publish());
    }

    @Test
    public void testPublishFailure() throws Exception{
        Sample sample = new Sample();
        PowerMockito.when(sample.invoke(Mockito.anyString())).thenReturn("failure");
        PowerMockito.whenNew(Sample.class).withNoArguments().thenReturn(sample);

        Main m = new Main();
        Assert.assertEquals("Expected result not found","failure",m.publish());
    }

    @Test(expected = ServiceFailureException.class)
    public void testPublishException() throws Exception{
        Sample sample = new Sample();
        PowerMockito.when(sample.invoke(Mockito.anyString())).thenThrow(new InvalidNameException("Invalid name provided"));
        PowerMockito.whenNew(Sample.class).withNoArguments().thenReturn(sample);

        Main m = new Main();
        m.publish();
    }
}

随着 JUnit5 的引入，测试用例无法模拟创建新实例，因为 PowerMockRunner 不支持 JUnit5。

在 JUnit5 中使用 PowerMockito 的替代方法是什么。

解决方法

由于 PowerMockito 不支持 JUnit5，我们可以使用 Mockito 内联。这是替换 PowerMockito 的代码。

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;
import org.mockito.MockedConstruction;
import org.mockito.Mockito;
import org.powermock.api.mockito.PowerMockito;

import javax.naming.InvalidNameException;

public class MainTestJunit5 {

    @Test
    public void testPublishSuccess() {
        Main m = new Main();
        Assertions.assertEquals("success",m.publish(),"Expected result not found");
    }

    @Test
    public void testPublishFailure() throws Exception{
        try (MockedConstruction<Sample> mockedConstruction = Mockito.mockConstruction(Sample.class,(sampleMock,context) -> {
            Mockito.when(sampleMock.invoke(Mockito.anyString())).thenReturn("failure");
        })) {
            Sample sample = new Sample();
            PowerMockito.when(sample.invoke(Mockito.anyString())).thenReturn("failure");
            PowerMockito.whenNew(Sample.class).withNoArguments().thenReturn(sample);

            Main m = new Main();
            Assertions.assertEquals("Expected result not found","failure",m.publish());
        }
    }

    @Test
    public void testPublishException() throws Exception{
        try (MockedConstruction<Sample> mockedConstruction = Mockito.mockConstruction(Sample.class,context) -> {
            Mockito.when(sampleMock.invoke(Mockito.anyString())).thenThrow(new InvalidNameException("Invalid name found"));
        })){

            Main m = new Main();
            boolean error = false;
            try {
                m.publish();
            } catch (ServiceFailureException e) {
                error = true;
            }

            Assertions.assertTrue(error,"Exception throwing expected");
        }
    }
}

需要注意的几件事

• 设置 mockito-inline 需要额外的依赖项和额外的配置。
• 不需要额外的测试运行程序 (PowerMockRunner) 和测试准备。
• MockedConstruction 是有作用域的，因此您必须将所有模拟和处理放在该代码块中。
• JUnit5 消息是最后的方法参数。

Mockito 文档：https://javadoc.io/doc/org.mockito/mockito-core/latest/org/mockito/Mockito.html#49