Test case for expected behavior of to_json's :only option.

test_nested_hash_json_key_filtering.rb

begin
  require "bundler/inline"
rescue LoadError => e
  $stderr.puts "Bundler version 1.10 or later is required. Please update your Bundler"
  raise e
end

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

  git_source(:github) { |repo| "https://github.com/#{repo}.git" }

  gem "rails", github: "rails/rails"
end

require "active_support"
require "active_support/core_ext/object/blank"
require "minitest/autorun"

class BugTest < Minitest::Test
  def test_nested_hash_json_key_filtering
    nested_hash = { hash: { key: 'value' }, array: [{ key: 'value' }] }
    assert_equal nested_hash.as_json(only: [:hash]), { hash: { key: 'value' } }
    assert_equal nested_hash.as_json(only: [:array]), { array: [{ key: 'value' }] }
  end
end