Add a test for MessageChangedListener

[boris-petrov]

@marcelmay - this is a test that MessageChangedListener is called when flags are changed. It isn't though. I'm not sure if I'm doing something wrong or this is not supported by Greenmail?

As for the test itself:

1. I'm not sure saveChanges is needed?
2. I use a CountDownLatch to wait for the event to be triggered. That's fine but it might be better to use the idle mechanism as in the test before this one. I'm not sure it would work, however, I'm not very familiar with IMAP's protocol.

[marcelmay]

@boris-petrov , try

...
inboxFolder.addMessageChangedListener(listener);
inboxFolder.getMessages()[0].setFlag(DELETED, true); // Triggers the listener

The mail listeners need e.g. an IMAP operation (IDLE, FETCH ....) as trigger.

If you access an email via GreenMail server reference, you directly manipulate the mail 'on the server side' and 'raw', circumventing clients:

greenMail.getReceivedMessages()[0].setFlag(DELETED, true);

This is more of a GreenMail helper, and very limited as all the mail API objects were designed for client side usage.
E.g. jakarta.mail.Folder should be an interface but unfortunately is a an abstract class - very difficult to extend with a server side listener for setFlags ...

[boris-petrov]

@marcelmay thanks for the answer!

You're right that doing inboxFolder.getMessages()[0].setFlag(DELETED, true); triggers the listener. But I would like to have a listener for "external" events - that is, someone changing a flag not through the inboxFolder variable but through another mail client for example. Is that possible at all actually?

[marcelmay]

A loop issuing IMAP IDLE in a thread should trigger any listener

[boris-petrov]

@marcelmay I pushed a new commit that does what you're suggesting. I still can't make it work. Do you mind taking a look?

[marcelmay]

As commented, using the internal (server-side) API won't trigger any listeners. Because you directly manipulate the message in memory, and work around any JavaMail listener mechanism.

Instead, use IMAP / JavaMail:

inboxFolder.getMessages()[0].setFlag(DELETED, true); // Triggers the listener, as this results in an IMAP command

[boris-petrov]

@marcelmay I added another commit that does what you suggest. First I try with the same variable on which I've added the listener - that works as expected. Then I try with a new variable - then it doesn't. That's what I meant before by "external" event. Sorry, I should have removed the "server-side" setting of flags before. But please check the test now.

[marcelmay]

@boris-petrov , your test succeeds . I would close this PR for now, unless you still have issues?

If you have still issues, you you please rebase? Sorry I cleaned up/moved some tests.

[boris-petrov]

@marcelmay the test still doesn't pass on my side... I rebased on master and force-pushed. Please check the code to see what the test does. Perhaps I'm doing something wrong? Or maybe there is still an issue in Greenmail.

[marcelmay]

@boris-petrov : You're right, the test still fails. Thx for being persistent!