RSpec - Include Json matcher

include_json_matcher.rb

# frozen_string_literal: true

RSpec::Matchers.define :include_json do |expected|
  match do |response|
    values_match? expectation, actual
  end

  diffable

  # TODO: Make more informative failure massage with difference between actual and expected
  failure_message do |response|
    "response body: " \
      "#{JSON.pretty_generate(actual)} " \
      "doesn't match with: " \
      "#{JSON.pretty_generate(expectation)}"
  end

  description do
    "response #{expected.inspect}"
  end

  def expectation
    if expected.is_a?(Array)
      expected.map(&:deep_stringify_keys)
    else
      expected.deep_stringify_keys
    end
  end

  def actual
    Oj.load(response.body)
  rescue EncodingError
    response.body
  end
end

__END__

Expamples:

RSpec.descriver AnyController do
  describe '#index' do
    subject(:response) { get :index }
    
    let(:expectation) do
      {
        # TODO: #match_array used to avoid issues with sorting and require using string keys in array
        # TODO: Try to avoid using #match_array or stringify keys
        list: match_array([
          { 'id': 1 },
          { 'id': 2 }
        ])
      }
    end
    
    it { expect(response).to have_http_status(:success) & include_json(expectation) }
  end
end