In favor of String#is_utf8?.

I think this method was made for internal use only, and its usage was removed here: https://github.com/rails/rails/pull/8261/files#diff-ce956ebe93786930e40f18db1da5fd46L39.

- Adding a Float as a duration to a datetime would result in the Float
  being rounded. Doing something like would have no effect because the
  0.45 seconds would be rounded to 0 second.

  ```ruby
    time = DateTime.parse("2018-1-1")
    time += 0.45.seconds
  ```

  This behavior was intentionally added a very long time ago, the
  reason was because Ruby 1.8 was using `Integer#gcd` in the
  constructor of Rational which didn't accept a float value.

  That's no longer the case and doing `Rational(0.45, 86400)` would
  now perfectly work fine.

- Fixes #34008

Use String methods directly instead.

Check that options passed to the to_json are passed to all objects that
respond to as_json.

* Fix reading comment only encrypted files

When a encrypted file contains only comments then reading that files raises an error:

    NoMethodError: undefined method `deep_symbolize_keys' for false:FalseClass
        activesupport/lib/active_support/encrypted_configuration.rb:33:in `config'
        test/encrypted_configuration_test.rb:52:in `block in <class:EncryptedConfigurationTest>'

This happens because the previous implementation returned a `{}` fallback for blank YAML strings. But it did not handle YAML strings that are present but still do not contain any _usefull_ YAML - like the file created by `Rails::Generators::EncryptedFileGenerator` which looks like this:

    # aws:
    #   access_key_id: 123
    #   secret_access_key: 345

* Fix coding style violation

* Add backwardscompatible with Psych versions that were shipped with Ruby <2.5

* Do not rely on railties for Active Support test

* Simplify error handling

* Improve test naming

* Simplify file creation in test

```ruby
class FooNew
  def try(method_name = nil, *args)
    nil
  end
end

class FooOld
  def try(*args)
    nil
  end
end

require 'benchmark/ips'


foo_new = FooNew.new
foo_old = FooOld.new

Benchmark.ips do |x|
  x.report("new") { foo_new.try(:anything) }
  x.report("old") { foo_old.try(:anything) }
  x.compare!
end
# Warming up --------------------------------------
#                  new   250.633k i/100ms
#                  old   232.322k i/100ms
# Calculating -------------------------------------
#                  new      6.476M (± 4.8%) i/s -     32.332M in   5.005777s
#                  old      5.258M (± 3.2%) i/s -     26.485M in   5.042589s

# Comparison:
#                  new:  6476002.5 i/s
#                  old:  5257912.5 i/s - 1.23x  slower
```

It's worth noting that checking for nil separately as in https://github.com/rails/rails/pull/34067 seems to be MUCH faster. It might be worth it to apply a blanket `&.` to every internal `try` call.

the document has been disappeared since the method became private at c2bfe6cb

- Following the Rails guide which state that a logger needs to include
  the `ActiveSupport::LoggerSilence` as well as
  `ActiveSupport::LoggerThreadSafe` modules isn't enough and won't
  work.

  Here is a test cases with 3 tests that all fails
  https://gist.github.com/Edouard-chin/4a72930c2b1eafbbd72a80c66f102010

  The problems are the following:

  1) The logger needs to call `after_initialize` in order to setup
  some instance variables.
  2) The silence doesn't actually work because the bare ruby Logger
  `add` method checks for the instance variable `@logger`. We need to
  override the `add` (like we used to in the ActiveSupport::Logger
  class).
  3) Calling `debug?` `info?` etc... doesn't work as the bare ruby
  methods will check for the instance variable. Again we need to
  override this methods (like we used to in the ActiveSupport::Logger
  class)

  The LoggerSilence won't work without LoggerThreadSafe, but the later
  is not public API, the user shouldn't have to include it so I
  modified to include it automatically.
  Same for the `after_initialize` method. I find unuintitive to have
  to call it directly. I modified to instance the variables when the
  module get included.

- I found this weird that the LoggerSilence wasn't using the
  `ActiveSupport` namespace (AFAIK all other classes have it).

  This PR deprecate the use of `LoggerSilence` for
  `ActiveSupport::LoggerSilence` instead.

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'

[Gannon McGibbon + Eric Turner]

- LoggerThreadSafeLevel does nowaday since 2518bda9

* Handle more unsafe String methods

* Fix codeclimate issue

* Revert stylistic change

[Janosch Müller + Rafael Mendonça França]

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

```

The `merged_options` method is private and the output is never mutated.
Using this info we can get rid of the `dup` behavior. We can also
eliminate the `merge` call in the case where all the options being merged are the same.

Returned results are frozen as an extra layer of protection against
mutation.

Before

```
Total allocated: 741749 bytes (6642 objects)
```

After

```
Total allocated: 734039 bytes (6648 objects)
```

Diff

```
(741749 - 734039) / 741749.0 => ~ 1.0 %
```

If you don't feel comfortable modifying this method, we could rename it
and only use it internally.

- 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.

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!).

Followup to a recently merged PR, too minor and detailed to require a
modification to the contributed patch.

Closes #32885.

Fixing code block rendering, indentation, backticks, etc.

Co-authored-by: Nno-itsbackpack <no-itsbackpack@github.com>