Ruby exception wrapping

base_wrapper_exception.rb

# A generic error that implementations can use to wrap their exceptions with
class BaseWrapperException < StandardError
  def initialize(e = nil)
    super e
    return self unless e.present? && e.is_a?(Exception)
    # Preserve the original exception's data
    set_backtrace e.backtrace
    message.prepend "#{e.class}: "
  end
end

require 'test_helper'

class BaseWrapperExceptionTest < ActiveSupport::TestCase
  should 'wrap exceptions' do
    class TestClass
      def self.some_test_method
        raise StandardError.new('you broke it!')
      end
    end

    original = assert_raises StandardError do
      TestClass.some_test_method
    end

    e = BaseWrapperException.new(original)

    # Should preserve all of the original exception's information
    assert e.message[/you broke it/], 'expected original exception message to be preserved'
    assert e.message[/StandardError/], 'expected original exception to be in message'
    assert e.backtrace.any? {|s| s[/some_test_method/]}, 'expected new exception to contain original backtrace'
  end
end