Functional tests vs. integration tests

[ipoerner]

There's a thin border - if at all - between functional and integration tests as described by Jamis Buck here: http://weblog.jamisbuck.org/2007/1/30/unit-vs-functional-vs-integration .

There are only functional tests in ActiveMailbox at the moment, and no integration tests. However, one could argue that access to IMAP folders and messages - requiring a user to generate the ActiveMailbox domain classes and provide a number of IMAP accounts to work on - would probably be considered integration tests. Also, issue #12 brings up classification tests, which would fit much more into the functional test category and seem somewhat more low level, compared to the folder/message handling.

To make a long story short, the current layout should probably be overhauled.