commit 2ca572c249daea6d24c1b737565f6018c8cb792c
author Dave Borowitz <dborowitz@google.com> Mon Jun 12 17:08:54 2017 -0400
committer Dave Borowitz <dborowitz@google.com> Tue Jun 13 12:05:57 2017 -0400
tree 8b0f30152d454cd7a072c83a32ac1d126507b23c
parent 6720589c6364233084a32076d78b4845b9fa1ba5

Add enum type representing the order of NoteDb migration

When we first implemented NotesMigration, we were interested in the
low-level details of how the migration state affects Gerrit server code.
It was always clear that not all combinations of micro-states were
supported or even made sense, but we weren't entirely sure at the time
which combinations *were* important.

Now that we've finished the NoteDb migration for gerrit-review, we have
a much clearer picture, and are ready to explicitly declare the set of
supported migration states, that is, the subset of supported
NotesMigration method combinations. Encapsulate these in a new enum
class NotesMigrationState; this remains independent of NotesMigration so
that low-level implementation code can continue querying only the facets
it's interested in.

This new enum allows us to clean up some test setup, reusing it from
NoteDbMode and RebuildNoteDbIT. Note that NoteDbMode is still a separate
enum: it covers only a subset of the NotesMigrationStates, and it needs
to support different behaviors within the same state (OFF vs. CHECK).

Change-Id: I480ce13837f2ba5477a62d3105cf61d746d25845