Add :only option to assert_enqueued_jobs

With the option, assert_enqueued_jobs will check the number of times a specific kind of job is enqueued.

Fix potenital infinite recursion in changed_for_autosave?

Fix count on a separate connection

Previosly count and other AR calculations would convert
column_name_for_operation to sql on a default Arel::Table.engine
(AR::Base) connection. That could lead to trouble if current
model has a connection to a different adapter or Base connection
is inaccessible.

Overwrite descriptions generated by Generators::Base to respect acronym.

Add _mailer suffix to generated file names.

The build has failed when running the date/time ext tests in isolation
due to the missing extension, so better than adding a require is using
just Ruby in this case.

https://travis-ci.org/rails/rails/jobs/46107954#L1077

fix `attribute` method scoping(i.e. private)

Changing sets -> set [ci-skip]

Updating some minor grammar issue.

Add #weekend?, #next_weekday, and #prev_weekday methods to Date, Time, and DateTime

ref #52f64126

Following the same naming convention used in
controllers and jobs.

Add log_level options to configuration guide

replacing 'attribute' method with an alias

 Fixed typos and wording in ActiveRecord CHANGELOG [ci skip]

Fix lookup of fixtures with non-string(like Fixnum) label

 - Fixtures with non-string labels such as integers should be accessed
   using integer label as key. For eg. pirates(1) or pirates(42).
 - But this results in NotFound error because the label is converted into string before
   looking up into the fixtures hash.
 - After this commit, the label is converted into string only if its a
   symbol.
 - This issue was fount out while adding a test case for
   https://github.com/rails/rails/commit/7b910917.

Add #prev_day and #next_day as counterparts to #yesterday and #tomorrow for Date, Time, and DateTime

`#on_weekend?` returns true if the receiving date/time falls on a Saturday or
Sunday.

`#next_weekday` returns a new date/time representing the next day that does
not fall on a Saturday or Sunday.

`#prev_weekday` returns a new date/time representing the previous day that
does not fall on a Saturday or Sunday.

Improve protect_from_forgery documentation.

removing unecessary default parameter in private method

Documenting 'remove_possible_method' and 'redefine_method' [ci skip]

'_singularize' only ever gets called with one argument

Propagate bind_values from join in subquery

`initialize_internals_callback` will attempt to assign attributes from
the current scope, which will fail if something defined the method
and calls super (meaning it won't hit `method_missing`).

Fixes #18339