Support unit testing AR models without loading all of rails

gistfile1.rb

require "active_record"

# Also highly recommended:
# require "active_support/dependencies"
# ActiveSupport::Dependencies.autoload_paths += [ "app/models" ]
# ..so you don't need to do manual requires, found it to be just as fast.

# Support unit testing AR models without loading all of rails.
connection_info = YAML.load(ERB.new(File.read("config/database.yml")).result)["test"]
ActiveRecord::Base.establish_connection(connection_info)

# For errors_on in tests
require 'rspec/rails/extensions/active_record/base'

# Disable write queries
module ActiveRecord
  UNIT_MESSAGE = "Persistance disabled in unit specs, if you want to test persistance put the example in spec (we want to keep unit tests fast)."

  class Base
    def readonly?
      true
    end
  end

  class ReadOnlyRecord
    def message
      UNIT_MESSAGE
    end
  end
end

# Disable read queries
connection = ActiveRecord::Base.connection

def connection.select_all(*)
  raise ActiveRecord::UNIT_MESSAGE
end

def connection.select_value(*)
  raise ActiveRecord::UNIT_MESSAGE
end

# Making uniqueness validations no-ops
class ActiveRecord::Validations::UniquenessValidator
  def validate_each(record, attribute, value)
    # no-op
  end
end