`setup do` creates unnecessary allocations of proc objects in callbacks.
This prevents that from happening and results in faster code.

add `DateTime.now` to list of `TimeHelpers#travel_to` stubbing [ci skip]

Require pg ~> 0.18 to ensure Ruby 2.2 compatibility

ActiveJob: queue_adapter can be inherited

This allows different `queue_adapters` to be used in each `ActiveJob`
class heirarchy. Previously, all subclasses used a single global queue
adapter.

Versions of the pg gem earlier than 0.18.0 cannot be used safely with Ruby 2.2.
Specifically, pg 0.17 when used with Ruby 2.2 has a known bug that causes
random bits to be added to the end of strings. Further explanation here:
https://bitbucket.org/ged/ruby-pg/issue/210/crazy-bytes-being-added-to-record

Action Controller guide edits for grammar and clarity

`ActiveJob::QueueAdapters::*` are no longer singletons

This introduces undesirable `Rails.logger` formatters (such as the syslog
formatter) onto a `Logger.new(STDERR)` for the console. The production
logger may be going elsewhere than standard io, so we can't presume to
reuse its formatter.

With syslog, this causes missing newlines in the console, so irb prompts
start at the end of the last log message.

We can work to expose the console formatter in another way to address
the original issue.

This reverts commit 026ce5dd, reversing
changes made to 6f0a69c5.

Unnecessary usage of self in the guides [ci skip]

I deleted self from the callbacks guides code example because it's unnecessary and this way it's more like the other examples where self was not used.

[ci skip] Change to code element

This change was prompted by 598b8418.

There was a typo in the `:requires_new` option. This led
to `#<ArgumentError: unknown keyword: require_new>` leaving all the
triggers in a disabled state.

Upd pg json_test

Let strip_tags leave HTML escaping to Rails.

Prevents double escaping errors, such as "&" becoming "&".

As of Ruby 2.2, Psych can handle any object which is marshallable. This
was not true on previous versions of Ruby, so our delegator types had to
provide their own implementation of `init_with` and `encode_with`.
Unfortunately, this doesn't match up with what Psych will do today.

Since by the time we hit this layer, the objects will have already been
created, I think it makes the most sense to just grab the current type
from the class.

I should have done this in the first place. We are now serializing an
explicit version so we can make more careful changes in the future. This
will load Active Record objects which were serialized in Rails 4.1.

There will be bugs, as YAML serialization was at least partially broken
back then. There will also be edge cases that we might not be able to
handle, especially if the type of a column has changed.

In addition, we're passing this as `from_database`, since that is
required for serialized columns at minimum. All other types were
serializing the cast value. At a glance, there should be no types for
which this is a problem.

Finally, dirty checking information will be lost on records serialized
in 4.1, so no columns will be marked as changed.

remove unnecessary autoload path parameters

‘test_after_commit’ gem is not require in Rails 5, remove note from doc ...

Changed 'blank space' to 'blank line'

Line 85 stated that fixtures are typically separated by a blank space. I changed the wording to blank line because blank space could be misinterpreted as a non-breaking space character when in reality, each fixture record (in YAML) is separated by a blank line.

The table is being modified in tests, without reloading the column
information on the appropriate class. This is leading to incorrect
column information in many cases.

The failures fixed by this commit can be replicated with:

    ARCONN=postgresql ruby -Itest test/cases/adapters/postgresql/hstore_test.rb --seed 21574

This fixes the reasons 4cf3b8ac, 303567e5, and fa634484 needed to be
reverted in 71420598. The revert has been reverted and this fixes
the issues caused previously.

If we call `super` first we will end up nuking the session settings in the
application tests that do `setup do` - so any session login or cookie
settings will not be persisted thoughout the test sessions.

Calling `super` last prevents `@integration_session` from getting nuked
and set to nil if it's already set.

Test added to prevent regression of this behavior in the future.

This reverts commit 71420598.

Fix place of require 'rails_guides/markdown'

The default value of `"pg_arrays"."tags"` is being changed to `[]` in
one test, but the column information on the model isn't reset after it's
changed back. As such, we think the default value is `[]` when in the
database it's actually `nil`. That means any test which was assigning
`[]` to a new record would have that key skipped with partial writes, as
it hasn't changed from the default. However since the *actual* default
value is `nil`, we get back values that the test doesn't expect, and it
fails.

use public Module#include instead of send :include [ci skip]

Reverting this as it's not the implementation that we would like it to be.
This is being used inside of ActiveSUpport::TimeZone[] and it's unaware
of the context in which to find the timezone period so the timezone found
changes depending on whether DST is in effect for the current period.
This means that `'2001-01-01'.in_time_zone(-9)` changes from winter/summer
even though it's the same date that we're trying to convert.

Since finding timezones by numeric offsets is a bit hit and miss we should
introduce a new API for finding them which supplies the date context in
which we want to search and we should probably also deprecate the finding
of timezones via the [] method, though this needs further discussion.

This reverts commit 2cc2fa36.