“If it’s not tested assume it’s broken.” This is one of the mantras in my company. Sometimes it’s easier said then done. If I always had to test everything I would be doing nothing but testing. So I employ different techniques to keep me programming and the computer to test the code I write.

One of the nice things about Rails is that you have a whole array of tools to automate testing and at least one very nice tool to let you know what’s tested and what’s not. Yes I am talking about Rcov.

Rcov has been “the bee’s knees” for code coverage awareness. Recently I have noticed Rcov has been doing more work then expected. When I ran the rcov command in a rails project it tested everything. I mean everything, including gems installed on the system.

Since everything is just a bit too much for my project I started looking for a way to limit the output. It appears I had to use -x option to stop the code coverage tool from traversing the gems. Here is the whole task:

desc 'Measures test coverage using rcov'
Rcov::RcovTask.new(:rcov) do |rcov|
  rcov.pattern    = "test/**/*_test.rb"
  rcov.rcov_opts  = [
    "-x 'gems/.*,rubygems/.*,rcov/.*'",
    "-T",
    "--rails" ]
  rcov.output_dir = “rcov/unified”
end

I hope this helps you.

While working on a research tool for my work I have noticed that my ruby solution rounds differently then the original c# .net code. It was not in every but about 10 percent of my tests failed due to the different rounding schemes.

Ruby uses the Symmetric Arithmetic Rounding while C# .net uses the Gaussian rounding otherwise known as the Banker’s routing.

I have looked for a quick solution for Ruby but Google did not return a result I could immediately use. I have found a javascript solution which I translated to Ruby.

Additionally I have added a “decimal” parameter to specify the precision of rounding.

Here is the code:

class Numeric
  def _round(val)
    sign = val < 0 ? -1 : 1
    return (val.abs.round * sign) if (val.abs - val.abs.floor) != 0.5
    return (val.abs.ceil  * sign) if val.abs.floor % 2 == 1
    return (val.abs.floor * sign)
  end

  def gaussian_round(decimals = 0)
    return (_round(self * (10**decimals))/((10**decimals).to_f))
  end
end

I have been looking into automating some of my development tasks in Cocoa/Xcode environment.  For the longest time I was using Subversion which would integrate quite well with Xcode. Recently, however, I have been exploring other version control systems.  Especially git.  Since it’s a much newer (D)VCS it does not have as much integration into systems as subversion.

I have managed to find some interesting solutions to include Git version number in Xcode project however the only actual solutions I have found are written in languages I don’t care for anymore.  Yes I can program in them but why would I want to.

So here is a quick solution written in MacRuby.

#!/usr/local/bin/macruby

git_output = `git show --abbrev-commit`
commit_version = git_output.split("\n").grep(/^commit/).first
version = commit_version.gsub(/^commit\s+(.*)\.{3}/, "\\1")
if version
  list = NSMutableDictionary.dictionaryWithContentsOfFile("Info.plist")
  list["CFBundleVersion"] = version
  list.writeToFile(’Info.plist’, :atomically => true)
end

In my final solution I intend to have an output in following format:

major.minor.revision (build)

where the “build” is going to correspond with the git commit version
and the other parts will reflect the marketing version numbers.

I have always been a fan of open source and wanted to contribute some code to a project or two. Somehow, I never found a project I would really enjoy and could directly benefit from as well. I was simply looking for an project that would scratch my itch.
Finally while working on an e-commerce system for my company I have decided to use active_merchant to connect to PayPal. The original implementation used by active_merchant was targeting and older xml based gateway and I have decided to re-implement the gateway using more recent NVP (name-value pair) interface. Hopefully this will allow for more modern features of the PayPal service.
A few days ago Cody has committed my patch and it is currently part of the active_merchant main code.

I have also created git repository where I can add more functionality as needed.
Here is the link for the interested:

git clone http://git.furmanek.net/active_merchant.git

Enjoy.

Dave Thomas shows how to make ruby into a beautiful meta-programming language. So if you want to know how things like has_many in Ruby on Rails works, here is your chance.

http://www.infoq.com/presentations/metaprogramming-ruby

My friend Brent (site) has been experimenting with some ruby code optimizations for joining strings. It appears you can squeeze quite a bit of more performance with a small change in code.

Here is the original code which took 13.8 seconds:

a = ''
(0..10000).each do |counter|
  a += 'a'
end

Now an alternative version that is a bit faster (0.127 seconds):

a = ''
(0..10000).each do |counter|
   a << 'a'
end

So if you want to join a lot of strings you may want to consider the alternate method. It may save you some time.