Override inspect on ruby objects

inspector.rb

# When an RSpec test like this fails,
# 
#   @my_array.should == [@some_model, @some_model2]
# 
# RSpec will call inspect on each of the objects to "help" you figure out
# what went wrong. Well, inspect will usually dump a TON OF SHIT and make trying
# to figure out why `@my_array` is not made up of `@some_model` and `@some_model2`.
#
# This little module and technique helps get around that. It will redefine `inspect`
# if you include it in your model object. 
# 
# You can define a whitelist of methods that inspect will dump.
# It will always provide `object_id` at a minimum. 
# 
# To use it, drop it in spec/support/inspector.rb and class_eval the models to
# override `inspect`.
module Inspector
  
  def inspect
    string = "#<#{self.class.name}:#{self.object_id} "
    fields = self.class.inspector_fields.map{|field| "#{field}: #{self.send(field)}"}
    string << fields.join(", ") << ">"
  end
  
  def self.inspected
    @inspected ||= []
  end
  
  def self.included source
    # $stdout.puts "Overriding inspect on #{source}"
    inspected << source
    source.class_eval do
      def self.inspector *fields
        @inspector_fields = *fields
      end
      
      def self.inspector_fields
        @inspector_fields ||= []
      end
    end
  end
end

# Examples

# For use when testing you can class eval the model you want
# to override the inspect behavior on.
User.class_eval do
  include Inspector
  inspector :id, :email, :company_id
end

# There's also nothing stopping you from doing this in
# any ruby class
class User
  # ...
  include Inspector
  inspector :id, :email, :company_id
  #...
end

puts User.new.inspect
# => #<User:0x10c7a2f80 id: 1, email: "tyler@example.com", company_id: 1>

Nice one!
It'd be even better if you do self.send(field).inspect, so things that need quotation marks have them in the inspect.

Make it a gem!

Make it a gem!

💯