模拟 MIMEMessage 的正确方法？

Question

我想实际验证消息上设置的字段，如正文、主题、发件人等……我也尝试过使用参数捕捉器，但没有用，当我调试代码时，消息在获取 javaMailSender.send(message) 行时始终显示空字段。

是否有模拟 MIMEMessage 的最佳实践？

//EmailService.java

import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;

import javax.mail.MessagingException;
import javax.mail.internet.MimeMessage;

@Slf4j
public class EmailService {
    private JavaMailSender javaMailSender;

    @Autowired
    public EmailService(JavaMailSender javaMailSender) {
        this.javaMailSender = javaMailSender;
    }


    public void sendEmail() {
        MimeMessage message = javaMailSender.createMimeMessage();
        String body = "<html>\n" +
            "<p> This the body </p>\n" +
            "<br>\n";
        try {
            MimeMessageHelper mimeMessageHelper = new MimeMessageHelper(message, true);
            mimeMessageHelper.setSubject("subject");
            mimeMessageHelper.setTo("stack@overflow.com");
            mimeMessageHelper.setFrom("overflow@stack.com");
            mimeMessageHelper.setText(body, true);

            javaMailSender.send(message);

        } catch (MessagingException e) {
            log.error("error");
        }`enter code here`
    }
}

下面是测试

//EmailServiceTest.java

import org.junit.Before;
import org.junit.Test;
import org.mockito.ArgumentCaptor;
import org.mockito.Mock;
import org.springframework.mail.javamail.JavaMailSender;

import javax.mail.MessagingException;
import javax.mail.internet.MimeMessage;
import java.io.IOException;

import static org.junit.Assert.assertEquals;
import static org.mockito.Mockito.*;
import static org.mockito.MockitoAnnotations.initMocks;


public class EmailServiceTest {
    private EmailService emailService;

    @Mock
    private JavaMailSender javaMailSender;

    @Mock
    private MimeMessage message;

    @Before
    public void setUp() throws IOException {
        initMocks(this);

        emailService = new EmailService(javaMailSender);
    }

    @Test
    public void sendEmail_sendsEmailWithCorrectContent() throws MessagingException {
        ArgumentCaptor<MimeMessage> mimeMessageArgumentCaptor = ArgumentCaptor.forClass(MimeMessage.class);
        when(javaMailSender.createMimeMessage()).thenReturn(message);

        doNothing().when(javaMailSender).send(message);

        emailService.sendEmail();

        verify(javaMailSender, times(1)).send((mimeMessageArgumentCaptor.capture()));
        assertEquals("subject", mimeMessageArgumentCaptor.getValue().getSubject());
    }

}

Answer 1

进行这种测试通常更容易 using an integration test。电子邮件通常是使用 freemarker 等模板库构建的，因此集成测试对于验证您的模板是否正确也很有价值。

您可以通过使用 PowerMock 创建模拟 MimeMessageHelper 来进行单元测试，但 PowerMock 有时在跟上其他测试库的变化方面可能很慢，并且此类测试通常最终会变得脆弱而且价值不大。例如，您可以验证 setSubject() 在 mimeMessageHelper 上被调用，但这是否会产生您真正想要测试的结果（主题在 message 上设置）？

模拟 MIMEMessage 的正确方法？

Proper way to mock MIMEMessage?

java

mockito

jakarta-mail

mime