This adds the same suggestions added here:
https://github.com/rails/rails/blob/01a69e27a4e55504af8fe776826d659550e6f89e/activejob/lib/rails/generators/job/templates/application_job.rb

These appear when `app/jobs/application_job.rb` doesn't exist, but not
for new applications.

Since this is a test to check the behavior of `load_defaults`,
webpacker is unnecessary.

Until #34050 can be resolved

This reverts commit 7f870a5b, reversing
changes made to 65568988.

* Use Webpacker by default on new apps

* Stop including coffee-rails by default

* Drop using a js_compressor by default

* Drop extra test for coffeescript inclusion by default

* Stick with skip_javascript to signify skipping webpack

* Don't install a JS runtime by default any more

* app/javascript will be the new default directory for JS

* Make it clear that this is just for configuring the default Webpack framework setup now

* Start using the Webpack tag in the default layout

* Irrelevant test

* jQuery is long gone

* Stop having asset pipeline compile default application.js

* Add rails-ujs by default to the Webpack setup

* Add Active Storage JavaScript to application.js pack by default

* Consistent quoting

* Add Turbolinks to default pack

* Add Action Cable to default pack

Need some work on how to set the global consumer that channels will
work with. @javan?

* Require all channels by default and use a separate consumer stub

* Channel generator now targets Webpack style

* Update task docs to match new generator style

* Use uniform import style

* Drop the JS assets generator

It was barely helpful as it was. It’s no longer helpful in a Webpacked
world. Sayonara!

* Add app/javascript to the stats directories

* Simpler import style

Which match the other imports.

* Address test failures from dropping JS compilation (and compression)

* webpacker-default: Modify `AssetsGeneratorTest`

Before:

```
$ bin/test test/generators/assets_generator_test.rb
Run options: --seed 46201

F

Failure:
AssetsGeneratorTest#test_assets [/Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/assets_generator_test.rb:12]:
Expected file "app/assets/javascripts/posts.js" to exist, but does not

bin/test /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/assets_generator_test.rb:10

.

Finished in 0.031343s, 63.8101 runs/s, 95.7152 assertions/s.
2 runs, 3 assertions, 1 failures, 0 errors, 0 skips
```

After:

```
$ bin/test test/generators/assets_generator_test.rb
Run options: --seed 43571

..

Finished in 0.030370s, 65.8545 runs/s, 65.8545 assertions/s.
2 runs, 2 assertions, 0 failures, 0 errors, 0 skips
```

* webpacker-default: Modify `ChannelGeneratorTest`

Before:

```
$ bin/test test/generators/channel_generator_test.rb
Run options: --seed 8986

.F

Failure:
ChannelGeneratorTest#test_channel_with_multiple_actions_is_created [/Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:43]:
Expected file "app/assets/javascripts/channels/chat.js" to exist, but does not

bin/test /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:34

.F

Failure:
ChannelGeneratorTest#test_channel_is_created [/Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:29]:
Expected file "app/assets/javascripts/channels/chat.js" to exist, but does not

bin/test /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:22

E

Error:
ChannelGeneratorTest#test_cable_js_is_created_if_not_present_already:
Errno::ENOENT: No such file or directory @ apply2files - /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/fixtures/tmp/app/assets/javascripts/cable.js

bin/test /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:60

F

Failure:
ChannelGeneratorTest#test_channel_suffix_is_not_duplicated [/Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:87]:
Expected file "app/assets/javascripts/channels/chat.js" to exist, but does not

bin/test /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:80

F

Failure:
ChannelGeneratorTest#test_channel_on_revoke [/Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:77]:
Expected file "app/assets/javascripts/cable.js" to exist, but does not

bin/test /Users/ttanimichi/ghq/github.com/ttanimichi/rails/railties/test/generators/channel_generator_test.rb:68

Finished in 0.064384s, 108.7227 runs/s, 481.4861 assertions/s.
7 runs, 31 assertions, 4 failures, 1 errors, 0 skips
```

After:

```
$ bin/test test/generators/channel_generator_test.rb
Run options: --seed 44857

.......

Finished in 0.060243s, 116.1961 runs/s, 697.1764 assertions/s.
7 runs, 42 assertions, 0 failures, 0 errors, 0 skips
```

* Fix shared generator tests.

* webpacker-default: Modify `ControllerGeneratorTest`

The JS assets generator was dropped. ref. https://github.com/rails/rails/commit/46215b179483d3e4d264555f5a4952f43eb8142a

* Revert "Simpler import style". It's currently failing with an error of "TypeError: undefined is not an object (evaluating '__WEBPACK_IMPORTED_MODULE_2_activestorage___default.a.start')". Waiting for @javan to have a look.

This reverts commit 5d3ebb71059f635d3756cbda4ab9752027e09256.

* require webpacker in test app

* Add webpacker without making the build hang/timeout. (#33640)

* use yarn workspaces to allow for installing unreleased packages and only generate js/bootsnap when required

* no longer need to have webpacker in env templates as webpacker moved this config to yml file

* Fix rubocop violation

* Got the test passing for the running scaffold

* update expected lines of code

* update middleware tests to account for webpacker

* disable js in plugins be default to get the tests passing (#34009)

* clear codeclimate report issues

* Anything newer than currently released is good

* Use Webpacker development version during development of Rails

* Edge should get development webpacker as well

* Add changelog entry for Webpacker change

Since Rails 6.0 will support Ruby 2.4.1 or higher
`# frozen_string_literal: true` magic comment is enough to make string object frozen.
This magic comment is enabled by `Style/FrozenStringLiteralComment` cop.

* Exclude these files not to auto correct false positive `Regexp#freeze`
 - 'actionpack/lib/action_dispatch/journey/router/utils.rb'
 - 'activerecord/lib/active_record/connection_adapters/sqlite3_adapter.rb'

It has been fixed by https://github.com/rubocop-hq/rubocop/pull/6333
Once the newer version of RuboCop released and available at Code Climate these exclude entries should be removed.

* Replace `String#freeze` with `String#-@` manually if explicit frozen string objects are required

 - 'actionpack/test/controller/test_case_test.rb'
 - 'activemodel/test/cases/type/string_test.rb'
 - 'activesupport/lib/active_support/core_ext/string/strip.rb'
 - 'activesupport/test/core_ext/string_ext_test.rb'
 - 'railties/test/generators/actions_test.rb'

Also we want to eager load routes before anything else.

The attribute methods for a model are currently defined lazily the first
time that model is instantiated, even when `config.eager_load` is true.
This means the first request to use each model incurs the cost, which
usually involves a database round trip to fetch the schema definition.

By defining the attribute methods for all models while the application
is booting, we move that work out of any individual request. When using
a forking web server, this also reduces the number of times the schema
definition is queried by doing it once in the parent process instead of
from each forked process during their first request.

In Ruby 2.3 or later, `String#+@` is available and `+@` is faster than `dup`.

```ruby
# frozen_string_literal: true

require "bundler/inline"

gemfile(true) do
  source "https://rubygems.org"

  gem "benchmark-ips"
end

Benchmark.ips do |x|
  x.report('+@') { +"" }
  x.report('dup') { "".dup }
  x.compare!
end
```

```
$ ruby -v benchmark.rb
ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-linux]
Warming up --------------------------------------
                  +@   282.289k i/100ms
                 dup   187.638k i/100ms
Calculating -------------------------------------
                  +@      6.775M (± 3.6%) i/s -     33.875M in   5.006253s
                 dup      3.320M (± 2.2%) i/s -     16.700M in   5.032125s

Comparison:
                  +@:  6775299.3 i/s
                 dup:  3320400.7 i/s - 2.04x  slower

```

Before this change this test was passing even if we revert #31135. The
reason for that is that `app 'development'` will load the environment in
the test process and it is happening before db_create_and_drop is
called.

This was not asserting that the environment was loaded in the db:create
task itself.

To test it we enhance the db:create task with a block that writes to a
tmp file the value of the config. If the environment is loaded before
that task enhancement runs the content of the file will have "true"
insteand of "false".

- Moving the `supports_cache_versioning?` check to a class method. 
- Shorten the method doc. 
- Expand on the error message.

If you are using the "in cache versioning" also known as "recyclable cache keys" the cache store must be aware of this scheme, otherwise you will generate cache entries that never invalidate.

This PR adds a check to the initialization process to ensure that if recyclable cache keys are being used via 

```
config.active_record.cache_versioning = true
```

Then the cache store needs to show that it supports this versioning scheme. Cache stores can let Rails know that they support this scheme by adding a method `supports_in_cache_versioning?` and returning true.

Fixes mistake left in https://github.com/rails/rails/pull/33521/files#diff-2a29095afcfe2c683b82a779a94c2208R59
and misunderstanding in https://github.com/rails/rails/commit/d69b04de0ff33237209afea6f6cac3ab27934908

When using environment specific credentials, `RAILS_MASTER_KEY` is not used.

For `production` environment look first for `config/credentials/production.yml.enc` file that can be decrypted by
`ENV["RAILS_MASTER_KEY"]` or `config/credentials/production.key` master key.
Edit given environment credentials file by command `rails credentials:edit --environment production`.
Default behavior can be overwritten by setting `config.credentials.content_path` and `config.credentials.key_path`.

Follow up #33883.

Suggested at https://github.com/rails/rails/pull/33876#issuecomment-421176221

Follow-up #33853

Once #33608 merged If users create a new database using MySQL 5.1.x, it will fail to create databases
since MySQL 5.1 does not know `utf8mb4` character set.

This pull request removes `encoding: utf8mb4` from `mysql.yml.tt`
to let create_database method handles default character set by MySQL server version.

`supports_longer_index_key_prefix?` method will need to validate if MySQL 5.5 and 5.6 server configured
correctly to support longer index key prefix, but not yet.

In production the query cache was already being loaded before the first
request even without #33856, so added a test to make sure of it.

This new test is passing even if #33856 is reverted.

It would allow `filter_attributes` to be reused across multiple
calls to `#inspect` or `#pretty_print`.

- Add `require "set"`
- Remove `filter_attributes` instance reader. I think there is no need
to keep it.

In a test app we observed that the query cache was not enabled on the
first request. This was because the query cache hooks are installed on
load and active record is loaded in the middle of the first request.

If we remove the `on_load` from the railtie the query cache hooks will
be installed before the first request, allowing the cache to be enabled
on that first request.

This is ok because query cache doesn't load anything else, only itself
so we're not eager loading all of active record before the first
request, just the query cache hooks.

[Eileen M. Uchitelle & Matthew Draper]

The name of the minitest library is spelled that way: regular font, and
lowercase. Lowercase is used even at the beginning of sentences, see

    http://docs.seattlerb.org/minitest/

I double-checked this with @zenspider too (thanks!).

* Use utf8mb4 character set by default

`utf8mb4` character set supports supplementary characters including emoji.
`utf8` character set with 3-Byte encoding is not enough to support them.

There was a downside of 4-Byte length character set with MySQL 5.5 and 5.6:

"ERROR 1071 (42000): Specified key was too long; max key length is 767 bytes"
for Rails string data type which is mapped to varchar(255) type.

MySQL 5.7 supports 3072 byte key prefix length by default.

* Remove `DEFAULT COLLATE` from Active Record unit test databases

There should be no "one size fits all" collation in MySQL 5.7.
Let MySQL server choose the default collation for Active Record
unit test databases.

Users can choose their best collation for their databases
by setting `options[:collation]` based on their requirements.

* InnoDB FULLTEXT indexes support since MySQL 5.6
it does not have to use MyISAM storage engine whose maximum key length is 1000 bytes.
Using MyISAM storag engine with utf8mb4 character set would cause
"Specified key was too long; max key length is 1000 bytes"

https://dev.mysql.com/doc/refman/5.6/en/innodb-fulltext-index.html

* References

"10.9.1 The utf8mb4 Character Set (4-Byte UTF-8 Unicode Encoding)"
https://dev.mysql.com/doc/refman/5.7/en/charset-unicode-utf8mb4.html

"10.9.2 The utf8mb3 Character Set (3-Byte UTF-8 Unicode Encoding)"
https://dev.mysql.com/doc/refman/5.7/en/charset-unicode-utf8.html

"14.8.1.7 Limits on InnoDB Tables"
https://dev.mysql.com/doc/refman/5.7/en/innodb-restrictions.html
> If innodb_large_prefix is enabled (the default), the index key prefix limit is 3072 bytes
> for InnoDB tables that use DYNAMIC or COMPRESSED row format.

* CI against MySQL 5.7

Followed this instruction and changed root password to empty string.
https://docs.travis-ci.com/user/database-setup/#MySQL-57

* The recommended minimum version of MySQL is 5.7.9
to support utf8mb4 character set and `innodb_default_row_format`

MySQL 5.7.9 introduces `innodb_default_row_format` to support 3072 byte length index by default.
Users do not have to change MySQL database configuration to support Rails string type.

https://dev.mysql.com/doc/refman/5.7/en/innodb-parameters.html#sysvar_innodb_default_row_format

https://dev.mysql.com/doc/refman/5.7/en/innodb-restrictions.html
> If innodb_large_prefix is enabled (the default),
> the index key prefix limit is 3072 bytes for InnoDB tables that use DYNAMIC or COMPRESSED row format.

* The recommended minimum version of MariaDB is 10.2.2
MariaDB 10.2.2 is the first version of MariaDB supporting `innodb_default_row_format`
Also MariaDB says "MySQL 5.7 is compatible with MariaDB 10.2".

- innodb_default_row_format
https://mariadb.com/kb/en/library/xtradbinnodb-server-system-variables/#innodb_default_row_format

- "MariaDB versus MySQL - Compatibility"
https://mariadb.com/kb/en/library/mariadb-vs-mysql-compatibility/
> MySQL 5.7 is compatible with MariaDB 10.2

- "Supported Character Sets and Collations"
https://mariadb.com/kb/en/library/supported-character-sets-and-collations/

Follow up of 3e814907.

We may not always have binstubs relative to the directory we are running
the rake task from. The particular case for this is with a mountable
Rails engine and dummy app that is created to test it. This sets all the
tasks up to run under an `app` namespace in
railties/lib/rails/tasks/engine.rake

This change resolves a problem whereby running `app:yarn:install` would
have no effect as it would try to run in the plugins bin directory
rather than the test/dummy/bin. This also means that it installs from
test/dummy/package.json and into test/dummy/node_modules which is
behaviour consistent with a normal Rails app.

On a rails engine:

```
➜  tmp rails plugin new rails-plugin --mountable
➜  tmp cd rails-plugin
```

Before this change:

```
➜  rails-plugin rake app:yarn:install
➜  rails-plugin
```

After this change:

```
➜  rails-plugin rake app:yarn:install
yarn install v1.9.4
info No lockfile found.
[1/4] 🔍  Resolving packages...
[2/4] 🚚  Fetching packages...
[3/4] 🔗  Linking dependencies...
[4/4] 📃  Building fresh packages...
✨  Done in 0.07s.
```

When this change is ran against a normal rails install there is not a
behavioural change:

```
➜  tmp rails new full-app
➜  tmp cd full-app
➜  full-app git:(master) ✗ rake yarn:install
yarn install v1.9.4
info No lockfile found.
[1/4] 🔍  Resolving packages...
[2/4] 🚚  Fetching packages...
[3/4] 🔗  Linking dependencies...
[4/4] 📃  Building fresh packages...
✨  Done in 0.09s.
```

Configuration item `config.filter_parameters` could also filter out sensitive value of database column when call `#inspect`

* Why
Some sensitive data will be exposed in log accidentally by calling `#inspect`, e.g.

```ruby
@account = Account.find params[:id]
payload = { account: @account }
logger.info "payload will be #{ payload }"
```

All the information of `@account` will be exposed in log.

* Solution
Add a class attribute filter_attributes to specify which values of columns shouldn't be exposed.
This attribute equals to `Rails.application.config.filter_parameters` by default.

```ruby
Rails.application.config.filter_parameters += [:credit_card_number]
Account.last.insepct # => #<Account id: 123, credit_card_number: [FILTERED] ...>
```

Fixing code block rendering, indentation, backticks, etc.

`spec` is the same variable name as gemspec generated by bundler, and its
intention is easier to understand than a one-letter variable.
https://github.com/bundler/bundler/blob/00fd58eaa69015092ee272c4cb5aa92a5e7ee45c/lib/bundler/templates/newgem/newgem.gemspec.tt#L11

This is follow up on 1c59b484. `spec` is already in use there.

This will avoid gems that are made to be private to be pushed to public
repositories.

The rake tasks which became deprecate now does not load the environment.
Therefore, even if the application specifies the behavior of deprecating,
the message is output to stderr ignoring the specification.

It seems that this is not the expected behavior.
We should respect the setting even in the rake tasks.

Related to #33773