Using the method you're testing to generate expected
values can lead to bugs being masked.

- When `as_json` returns `Infinity` or `NaN` as the value of any of the key,
  we don't used to call `as_json` on it as it was treated as primitive.
- This used to pass `Infinity` or `NaN` to `JSON.generate` and Ruby used
  to throw an error for `Infinity/NaN not allowed in JSON.`
- This patch changes the code to call `as_json` on these primitives so
  that they are converted to proper values before being passed to
  `JSON.generate`.
- Fixes #26877.

Style/SpaceBeforeBlockBraces
Style/SpaceInsideBlockBraces
Style/SpaceInsideHashLiteralBraces

Fix all violations in the repository.

The current code base is not uniform. After some discussion,
we have chosen to go with double quotes by default.

Where appropriate prefer the more concise Regexp#match?, String#include?,
String#start_with?, and String#end_with?

Fixes CVE-2015-3226

It’s used at so many places that extracting it out into a helper file
is worth doing.

Also added the missing CHANGELOG entry for #12183 @ 80e75520 and
4d02296c.

Got all the tests passing again.

Support for `encode_json` has been removed (and consequently the
ability to encode `BigDecimal`s as numbers, as mentioned in the
previous commit). Install the `activesupport-json_encoder` gem
to get it back.

This is because the new encoder will no longer support encode_json.
Therefore our only choice is to return `to_i` or `to_s` in
`BigDecimal#as_json`. Since casting a BigDecimal to an integer is
most likely a lossy operation, we chose to encode it as a string.

Support for encoding BigDecimal as a string will return via the
`activesupport-json_encoder` gem.

should also call #as_json on the children without options (instead of
nil)

Previously, calling `::JSON.{generate,dump}` sometimes causes
unexpected failures such as intridea/multi_json#86.

`::JSON.{generate,dump}` now bypasses the ActiveSupport JSON encoder
completely and yields the same result with or without ActiveSupport.
This means that it will **not** call `as_json` and will ignore any
options that the JSON gem does not natively understand. To invoke
ActiveSupport's JSON encoder instead, use `obj.to_json(options)` or
`ActiveSupport::JSON.encode(obj, options)`.

See [1] for why this is not a good idea.

As part of this refactor, circular reference protection in as_json has
been removed and the corresponding error class has been deprecated.

As discussed with @jeremy, circular reference error is considered
programmer errors and protecting against it is out of scope for
the encoder.

This is again based on the excellent work by @sergiocampama in #11728.

[1]: https://github.com/intridea/multi_json/pull/138#issuecomment-24468223

JSON.{dump,generate} offered by the JSON gem is not compatiable with
Rails at the moment and can cause a lot of subtle bugs when passed
certain data structures. This changed all direct usage of the JSON gem
in internal Rails code to always go through AS::JSON.{decode,encode}.

We also shouldn't be implementing `to_json` most of the time, and
these occurances are replaced with an equivilent `as_json`
implementation to avoid problems down the road.

See [1] for all the juicy details.

[1]: intridea/multi_json#138 (comment)

These methods now takes the same options as Hash#as_json, for example:

    struct = Struct.new(:foo, :bar).new
    struct.foo = "hello"
    struct.bar = "world"
    json = struct.as_json(only: [:foo]) # => {foo: "hello"}

This is extracted from PR #11728 from @sergiocampama, see also the
discussion in #11460.

TL;DR The primary driver is to remove autoload surprise.

This is related to #12106. (The root cause for that ticket is that
json/add defines Regexp#to_json among others, but here I'll reproduce
the problem without json/add.)

Before:

   >> require 'active_support/core_ext/to_json'
   => true
   >> //.as_json
   NoMethodError: undefined method `as_json' for //:Regexp
     from (irb):3
     from /Users/godfrey/.rvm/rubies/ruby-2.0.0-p195/bin/irb:16:in `<main>'
   >> //.to_json
   => "\"(?-mix:)\""
   >> //.as_json
   => "(?-mix:)"

After:

   >> require 'active_support/core_ext/to_json'
   => true
   >> //.as_json
   => "(?-mix:)"

This is because ActiveSupport::JSON is autoloaded the first time
Object#to_json is called, which causes additional core extentions
(previously defined in active_support/json/encoding.rb) to be loaded.

When someone require 'active_support/core_ext', the expectation is
that it would add certain methods to the core classes NOW. The
previous behaviour causes additional methods to be loaded the first
time you call `to_json`, which could cause nasty surprises and other
unplesant side-effects.

This change moves all core extensions in to core_ext/json. AS::JSON is
still autoloaded on first #to_json call, but since it nolonger
include the core extensions, it should address the aforementioned bug.

*Requiring core_ext/object/to_json now causes a deprecation warnning*