RSpec match nested JSON

json_match.rb

# May be used to match JSON strings in nested array/hashes
# Example:
# RSpec.describe(
#   { a: 1,
#     whatever: 'else',
#     nested_json: '[{"c":3},{"whatever":"else"}]'
#   }
# ) do
#   it { is_expected.to match(
#                         a_hash_including(
#                           a: 1,
#                           nested_json: json_match(
#                             a_collection_including(
#                               a_hash_including(c: 3)
#                             )
#                           )
#                         )
#                       )
#   }
# end
RSpec::Matchers.define :json_match do |expected|
  match do |actual_json|
    begin
      actual = JSON.parse(actual_json, symbolize_names: true)
    rescue JSON::ParserError
      return false
    end
    expect(actual).to match(expected)
  end

  failure_message do |actual|
    "expected #{actual} to match #{expected} as JSON"
  end

  failure_message_when_negated do |actual|
    "expected #{actual} not to match #{expected} as JSON"
  end
end