Assertion Class for Parsing JSON

have_json.rb

class HaveJson
  def initialize(selector)
    @actual = []
    @depths = []
    @selector = selector
    @path, @test = selector.split('=')
    @path = @path.split('/')
  end

  def matches?(json)
    #turn symbols into strings so path matching works
    h = {}
    json.each { |k, v| h[k.to_s] = v }
    json = h

    result = traverse(json, @path)
    max_depth = @depths.max || 0
    @closest = max_depth > 0 ? @path[max_depth - 1] : 'NO MATCHES'
    return result
  end

  def description
    "find selector in JSON"
  end

  def failure_message
    @actual.present? ? actual : closest
  end

  def closest
    "Closest node found: #{@closest}.\n"
  end

  def actual
    "Test: \"#{@test}\" Actual: #{@actual}\n"
  end

  def negative_failure_message
    "Found: #{@selector} in JSON string. Expected nil."
  end

private
  def traverse(json, path, depth=0)
    if path.size == 0
      @actual << json
      return @test.nil? || json.include?(@test)
    end

    if json.class == Array
      return json.map{|j| dig(j, path, depth+1)}.include? true
    else
      return dig(json, path, depth+1)
    end
  end

  def dig(json, path, depth)
    key, *rest = *path #pop current key
    if json.include? key
      @depths << depth
      return traverse(json[key], rest, depth)
    else
      return false
    end
  end
end

def have_json(selector)
  HaveJson.new(selector)
end