A Hash differ that needs to be cleaned and wrapped as a real gem imo.

gistfile1.rb

class Hash
  def diff(other)
    result = {}
    union = keys | other.keys
    
    result[:not_in_other] = (union - keys).inject({}) { |memo, k| memo[k] = other[k]; memo }
    result[:not_in_self] = (union - other.keys).inject({}) { |memo, k| memo[k] = self[k]; memo }
    
    result[:not_equal] = {}
    each do |key, value|
      result[:not_equal][key] = { :self => value, :other => other[key] } unless value == other[key]
    end
    
    result
  end
end