json2-fail.rb

gem 'json', '= 2.0.1'

require 'json'

JSON::VERSION # => "2.0.1"

json_string = '{}'

utf8_string          = json_string.dup.force_encoding('UTF-8')
utf8_string_frozen   = utf8_string.dup.freeze
ascii8_string        = json_string.dup.force_encoding('ASCII-8BIT')
ascii8_string_frozen = ascii8_string.dup.freeze

utf8_string.encoding             # => #<Encoding:UTF-8>
utf8_string_frozen.encoding      # => #<Encoding:UTF-8>
ascii8_string.encoding           # => #<Encoding:ASCII-8BIT>
ascii8_string_frozen.encoding    # => #<Encoding:ASCII-8BIT>

utf8_string.frozen?              # => false
utf8_string_frozen.frozen?       # => true
ascii8_string.frozen?            # => false
ascii8_string_frozen.frozen?     # => true

JSON.parse(utf8_string)          # => {}
JSON.parse(utf8_string_frozen)   # => {}
JSON.parse(ascii8_string)        # => {}
JSON.parse(ascii8_string_frozen) # can't modify frozen String (RuntimeError)