JSONAPI data size matcher

json_api_data_size_matcher.rb

# frozen_string_literal: true

RSpec::Matchers.define :have_data_count_of do |expected|
  match do |actual|
    if actual.is_a?(Hash)
      @json_api_payload = actual
    elsif actual.is_a?(String)
      @json_api_payload = JSON.parse(actual)
    else
      @invalid_payload_type_error = 'Please provide a Hash or JSON string'
      return false
    end

    unless data_payload
      @missing_data_key_error = "Can't find \"data\" key in JSON API payload"
      return false
    end

    unless data_payload.is_a?(Array)
      @invalid_data_type = '"data" is not an array'
      return false
    end

    data_payload.size == expected
  end

  failure_message do |_actual|
    if validity_error
      "Invalid payload: #{validity_error}"
    else
      "expected that JSONAPI \"data\" contains #{expected} elements but it contains #{@data_payload.size}"
    end
  end

  description do
    "expect that JSONAPI data contains #{expected} elements"
  end

  def validity_error
    @invalid_payload_type_error || @missing_data_key_error || @invalid_data_type
  end

  def data_payload
    @data_payload ||= @json_api_payload[:data] || @json_api_payload['data']
  end
end