"Printf" testing in Rails

Question

Hi, I'm new to Rails and I'm aware it has things such as unit-testing built in. But I'm interested in doing some more simple tests that are equivalent to your "printf" in C. So I'm testing a login page I've written and want to trace the code to see what each line like my find methods are returning. I try outputting with "puts" but I don't get anything in the command-line.

Answer 1

Are you familiar with ruby-debug?

1. Install the ruby-debug gem.

2. Start your server with the -u option.

   script/server -u

3. Put a debugger statement in your code where you want to stop.
4. You will have console access to your variables as well as the ability to step through your code.

Check the ruby-debug documentation for more details.

Answer 2

User something like this:

logger.info "method called with #{params.inspect}"

(you can put any variable inside the #{})

Once you're having fun with that, check out ./script/console and ruby-debug

Answer 3

I use puts statements all the time as well as the ruby debugger! It's great.

In rails you can do a couple things. I put "puts" in my code and when I run script/server at the command line, the output appears in my Terminal.app. I am running a Mac, but I am sure that there is a similar way to trace the activity of your app on your platform of choice.

The other option is to use the logger statement. you can call

logger.debug("My #{variable}")

and find these statements right in your log/development.log file.

Also, if you are running on a *nix system, you can use the "tail" command to trace the last statement written to your log one at a time.

tail -f log/development.log

This way you could write your statements and see them as they are happening. There are several levels of logging:

logger.warn
logger.info
logger.debug
logger.fatal

each environment (development, testing, production) will determine what "level" of logging will be called, so you may write log statements willy nilly with logger.debug while in development, but those log statements won't be written when you deploy based on the default log levels.

Answer 4

I've done this before - with Passenger, you don't have script/server's output, so I wrote this:

# extras/sexy_logging.rb
module SexyLogging
  def log(text)
    return true if RAILS_ENV == 'production'

    string = "\e[0;32mLog:\e[m #{text}"

    (100 - string.length).times do 
      string << ' '
    end
    string << "(#{caller.first})"

    logger.debug string
  end
end

ActiveRecord::Base.send               :include, SexyLogging
ActionController::Base.send           :include, SexyLogging

Then you can write

log variable

or

log 'Testing user'

tail -f log/development.log |grep Log:

and only see what you're logging, line by line and with colours.