exceptions are displayed in the console when integration testing with capybara

test_helper.rb

# Given an application, yield to a block to handle exceptions
class ExceptionRaiserApp
  def initialize(app, &block)
    @app = app
    @block = block
  end

  def call(env)
    @app.call(env)
  rescue => e
    @block.call(e)
  end
end

# Wrap ShortmailApp with the exception raiser
Capybara.app = ExceptionRaiserApp.new(ShortmailApp::Application) do |exception|
  # Write to standard error
  $stderr.write [
    # The name of the exception and its message
    exception.to_s + ": "+ exception.message,
    # And a nice clean rails backtrace
    Rails.backtrace_cleaner.clean(exception.backtrace, :silent),
    nil
  ].join("\n\t")+"\n"
  # Then re-raise so capybara gets a 500 and knows what's up
  raise exception
end