MIMEMessage and MIMEMessage mock test case fails with assertion error on EmailUtil - junit4

Question

What I'm trying to achieve - Simple unit test for my EmailUtil which i have written for a Spring MVC application.
Where I'm stuck - Though i have mocked the MIMEmessage and JavaMailSender, test case failing in MimeMessageHelper.set**** methods.
Appreciate any help on this as I have tried few different ways even using PowerMock and no luck for last couple of days.
EmailUtil.Java
import java.util.List;
import javax.activation.DataSource;
import javax.mail.MessagingException;
import javax.mail.internet.MimeMessage;
import javax.mail.util.ByteArrayDataSource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import com.dashboard.domain.Attachment;
import com.dashboard.domain.Email;
public class EmailUtil {
private static final Logger LOGGER = LoggerFactory.getLogger(EmailUtil.class
.getName());
/**
* Private constructor to make sure that no one creating instance
*/
private EmailUtil() {
}
/**
* Functionality to send the mail. This method used the mail sender
* configuration from spring-context file.
*
* #param email
* #param mailSender
* #throws MessagingException
*/
public static void sendEmail(JavaMailSender mailSender, Email email)
throws MessagingException {
LOGGER.info("Start of the method: sendEmail");
MimeMessage mimeMessage = mailSender.createMimeMessage();
// use the true flag to indicate you need a multi part message
boolean hasAttachments = email.getAttachments() != null
&& !email.getAttachments().isEmpty();
LOGGER.info(" mimeMessage - {} ",mimeMessage);
MimeMessageHelper helper = new MimeMessageHelper(mimeMessage,
hasAttachments);
LOGGER.info(" MimeMessageHelper - {} ",helper);
helper.setTo(email.getTo());
helper.setFrom(email.getFrom());
helper.setCc(email.getCc());
helper.setSubject(email.getSubject());
helper.setText(email.getText(), true);
List<Attachment> attachments = email.getAttachments();
if (!attachments.isEmpty()) {
for (Attachment attachment : attachments) {
String filename = attachment.getFilename();
DataSource dataSource = new ByteArrayDataSource(
attachment.getData(), attachment.getMimeType());
if (attachment.isInline()) {
helper.addInline(filename, dataSource);
} else {
helper.addAttachment(filename, dataSource);
}
}
}
mailSender.send(mimeMessage);
LOGGER.info("End of the method: sendEmail");
}
}
EmailUtilTest.Java
import static org.easymock.EasyMock.expect;
import javax.mail.Address;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMessage.RecipientType;
import org.easymock.EasyMock;
import org.easymock.Mock;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import com.dashboard.domain.ApplicationConstant;
import com.dashboard.domain.Email;
/**
* PowerMockDemo
* #author s.arumugam
*
*/
#RunWith(PowerMockRunner.class)
#PrepareForTest(EmailUtil.class)
public class EmailUtilTest {
Email email = new Email();
#Mock
JavaMailSender javaMailSender;
#Mock
MimeMessage mimeMessage;
#Mock
MimeMessageHelper mimeMessageHelper;
#Before
public void initList() {
email.setFrom(ApplicationConstant.DEFAULT_MAIL_ID.getValue());
email.setSubject("Subject");
email.setTo("to.email#userdomain.com");
email.setCc("admin#dashboard.com");
email.setText("Body of the email");
}
#Test
public void sendEmailTest() throws Exception{
mimeMessageHelper.setSubject(email.getSubject());
mimeMessageHelper.setFrom(new InternetAddress(email.getFrom(), true));
mimeMessageHelper.setCc(new InternetAddress(email.getCc()[0], true));
mimeMessageHelper.setTo(new InternetAddress(email.getTo()[0], true));
mimeMessageHelper.setText(email.getText());
expect(javaMailSender.createMimeMessage()).andReturn(mimeMessage);
Address sendTo[]={new InternetAddress(email.getTo()[0])};
mimeMessage.setRecipients(RecipientType.TO,sendTo);
EasyMock.expectLastCall().times(1);
EasyMock.replay(mimeMessage);
EasyMock.replay(javaMailSender);
EmailUtil.sendEmail(javaMailSender, email);
EasyMock.verify(mimeMessage);
EasyMock.verify(javaMailSender);
}
}
Error Message:
java.lang.AssertionError: Unexpected method call MimeMessage.setRecipients(To, [to.email#userdomain.com]):
MimeMessage.setRecipients(To, [to.email#userdomain.com]): expected: 1, actual: 0 at org.easymock.internal.MockInvocationHandler.invoke(MockInvocationHandler.java:44) at org.easymock.internal.ObjectMethodsFilter.invoke(ObjectMethodsFilter.java:94) at org.easymock.internal.ClassProxyFactory$MockMethodInterceptor.intercept(ClassProxyFactory.java:97) at $javax.mail.internet.MimeMessage$$EnhancerByCGLIB$$a6025b60.setRecipients(<generated>) at org.springframework.mail.javamail.MimeMessageHelper.setTo(MimeMessageHelper.java:581) at org.springframework.mail.javamail.MimeMessageHelper.setTo(MimeMessageHelper.java:595) at com.dashboard.util.EmailUtil.sendEmail(EmailUtil.java:50)

Answer 1

Ohh.. I managed to fix the issue.. purely by random trial and error..! That says I need to get into deep understanding of how these mock utils works.. Working test case below with a hope someone can find a complete working example with test case;
#RunWith(EasyMockRunner.class)
public class EmailUtilTest extends EasyMockSupport{
#Mock
JavaMailSender mailSender;
#Mock
MimeMessage mimeMessage;
#Test
public void testSendEmail() throws MessagingException{
Email email = new Email();
email.setFrom("from.email#dashboard.com");
email.setSubject("Subject");
email.setTo("to.email#userdomain.com");
email.setCc("admin#dashboard.com");
email.setText("Body of the email");
EasyMock.expect(mailSender.createMimeMessage()).andReturn(mimeMessage);
mailSender.send(mimeMessage);
EasyMock.expectLastCall();
EasyMock.replay(mailSender);
EmailUtil.sendEmail(mailSender, email);
EasyMock.verify(mailSender);
}
}

Answer 2

The reason you are getting java.lang.AssertionError is because EasyMock uses the equals() method to compare parameters passed to methods, and you cannot use equals() to compare arrays.
Address toAddress = new InternetAddress("a#b.com");
Address[] a1 = { toAddress };
Address[] a2 = { toAddress };
if (a1.equals(a2)) { // this will be false
// so this won't happen
}
Thankfully, EasyMock provides us with several different argument matchers. In this case we should use EasyMock.aryEq(). So in order to mock out the call to setRecipients() method:
mimeMessage.setRecipients(EasyMock.eq(RecipientType.TO) , EasyMock.aryEq(sendTo));
I'm not sure how the accepted answer is working without changes to the EmailUtil class.