json expression example

custom_matcher.rb

class HashBuilder

  def self.build &block
    hb = HashBuilder.new
    hb.instance_eval(&block)
    hb.hash
  end

  attr_reader :hash

  def initialize
    @hash = {}
  end

  def method_missing meth, *args, &block
    @hash[meth] = block ? HashBuilder.build(&block) : args.first
  end
end

class Schemas
  class << self
    def game(&block)
      attrs = { _links: {}.ignore_extra_keys,
                id: Fixnum,
                name: String,
                players: [player]
                
      }
      if block_given?
        attrs.merge(HashBuilder.build(&block))
      else
        attrs
      end
    end
    
    def player(&block)
      attrs = { _links: {}.ignore_extra_keys,
                id: Fixnum,
                name: String,
                email: String
      }
      if block_given?
        attrs.merge(HashBuilder.build(&block))
      else
        attrs
      end
    end
  end
end

# Usage

expect(JSON.parse(response.body)).to match_json_expression(Schemas.game do
  id 12
  players [ Schemas.player do
    name "some name"
  end]
end)