Tests for Inbox (offline tests)

[dwhswenson]

These are the tests that mock out the IMAP4 object. This assumes that the IMAP calls behave as expected: that the imaplib API does not change and that the behavior of IMAP requests (including Gmail IMAP extensions) does not change. Technically, there should be a second set of tests to ensure that these assumptions remain valid, but those are unlikely to change.

This will require the following:

• Mock(s) for Inbox.connection, probably with 2 emails in it, which should cover the following cases:
  • behavior for mock_imap.search is correct for cases where email search string is "ALL" or email search string is "SINCE" with a given time/date string
  • behavior for mock_imap.fetch is correct
• Mock(s) for GmailInbox.connection needs the following additional behaviors
  • at least one mocked message must have a label
  • mock_imap.uid("SEARCH", ...) should give the mock the behavior when searching by unique ID
  • mock_imap.uid("STORE", ...) should mock the behavior when setting labels
  • mock_imap.search needs to work when given the unique ID for a message

Implementation: Probably a stub class to mock out the necessary behaviors, which allows for subclass stubs?

NB: the incorrect unique ID problem identified in #52 should be fixed before some of these tests (especially around unique ID in Gmail) are implemented.