I think the test failure is due to this line, which directly references the Setting model when it may not exist (e.g. in rake before the database has been migrated).  Have a look at the DefaultSettings::Loader and you'll see it does this to return if Setting isn't already defined:

    30           # We may be executing something like rake db:migrate:reset, which destroys this table; only continue if the table exists
    31           Setting.first rescue return