fix warning in tests when using render_erb helper

Test helpers in erb using erb

ActiveRecord::Base.map method for direct select by single column

Log 'Filter chain halted as CALLBACKNAME rendered or redirected' every time a before callback halts.

Module#synchronize is deprecated with no replacement.  Please use `monitor` from ruby's standard library.

it clear which methods are synchronized.

the following code is deprecated:

Thread.new { Post.find(1) }.join

It should be changed to close the database connection at the end of
the thread:

Thread.new {
  Post.find(1)
  Post.connection.close
}.join

Only people who spawn threads in their application code need to worry
about this change.

pool.

This only existed to support methods like `set_table_name` in Active
Record, which are themselves being deprecated.

resolver.

association methods are now generated in modules

splited a long line to shorter ones

Fix typo in AS::TaggedLogging