Having trouble mocking an email server using JUnit - email

Question

I'm trying to mock sending an email (for the purposes of JUnit, v4.8.1, testing) and decided to use Dumbster, which I found through SO. I'm using version 1.6. I have this in my JUnit test …
SimpleSmtpServer server = SimpleSmtpServer.start();
boolean ret = m_emailSvc.sendEmail("me#me.com",
"you#you.com",
"localhost",
"Test",
"Test Body");
Assert.assertTrue(ret);
server.stop();
and I send an email this way …
public boolean sendEmail(final String toEmail,
final String fromEmail,
final String smtpHost,
final String subject,
final String body)
{
boolean ret = true;
// Get system properties
Properties properties = System.getProperties();
// Setup mail server
properties.setProperty("mail.smtp.host", smtpHost);
// Get the default Session object.
Session session = Session.getDefaultInstance(properties);
try{
// Create a default MimeMessage object.
MimeMessage message = new MimeMessage(session);
// Set From: header field of the header.
message.setFrom(new InternetAddress(fromEmail));
// Set To: header field of the header.
message.addRecipient(Message.RecipientType.TO,
new InternetAddress(toEmail));
// Set Subject: header field
message.setSubject(subject);
// Now set the actual message
message.setText(body);
// Send message
Transport.send(message);
}catch (MessagingException mex) {
ret = false;
LOG.error(mex.getMessage(), mex);
} // try
return ret;
} // sendEmail
This fails with the exception below. Does anyone know what I'm doing wrong or is there an easier way to mock sending an email in a JUnit test?
java.net.BindException: Permission denied
at java.net.PlainSocketImpl.socketBind(Native Method)
at java.net.PlainSocketImpl.socketBind(PlainSocketImpl.java:521)
at java.net.PlainSocketImpl.bind(PlainSocketImpl.java:414)
at java.net.ServerSocket.bind(ServerSocket.java:326)
at java.net.ServerSocket.<init>(ServerSocket.java:192)
at java.net.ServerSocket.<init>(ServerSocket.java:104)
at com.dumbster.smtp.SimpleSmtpServer.run(Unknown Source)
at java.lang.Thread.run(Thread.java:680)
[ERROR]: org.mainco.subco.email.service.EmailServiceImpl - Could not connect to SMTP host: localhost, port: 25
javax.mail.MessagingException: Could not connect to SMTP host: localhost, port: 25;
nested exception is:
java.net.ConnectException: Connection refused
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1934)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:638)
at javax.mail.Service.connect(Service.java:295)
at javax.mail.Service.connect(Service.java:176)
at javax.mail.Service.connect(Service.java:125)
at javax.mail.Transport.send0(Transport.java:194)
at javax.mail.Transport.send(Transport.java:124)
at org.mainco.subco.email.service.EmailServiceImpl.sendEmail(EmailServiceImpl.java:62)
at org.mainco.subco.email.service.EmailServiceTest.testSendEmail(EmailServiceTest.java:23)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:382)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:241)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:228)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:384)
at java.net.Socket.connect(Socket.java:527)
at java.net.Socket.connect(Socket.java:476)
at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:288)
at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:231)
at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:1900)

Answer 1

I decided to mock the static call from the Transport class instead, using PowerMock (v.1.5.1).
#RunWith(PowerMockRunner.class)
public class EmailServiceTest
{
#Autowired
private EmailService m_emailSvc = new EmailServiceImpl();
#Test
#PrepareForTest( Transport.class )
public final void testSendEmail()
{
suppress(methodsDeclaredIn(Transport.class));
boolean ret = m_emailSvc.sendEmail("me#me.com",
"you#you.com",
"localhost",
"Test",
"Test Body");
Assert.assertTrue(ret);
} // testSendEmail

Answer 2

What about wrapping the call to Transport is a mockable object? Inject the mock and verify the call.
What I mean is something like this...
class MyTransport{
public void send(MimeMessage message){
Transport.send(message);
}
}
Then inject an instance of this class into your class above. In your production env you have the same code. However, when doing testing you could pass in a Mock for MyTransport and thereby verify the call to send without the need of a server.