Just happened to stumble upon the following article at caboo.se: Handy dynamic rspec tip.

I immediately found a way of simplifying a test case that involves testing that an ever increasing number of videos can be transcoded:

   1  require File.dirname(__FILE__) + '/helper'
   2  require File.dirname(__FILE__) + '/../lib/transcoder.rb'
   3  
   4  context "Transcoder" do
   5    
   6    Dir.glob('videos/*').each do |video|
   7      it "should support #{video}" do
   8        Transcoder.convert(video, "site/#{video}.flv")[:file_size].should > 0
   9      end
  10    end
  11  end

You can also use it to test model validations:

   1  require File.expand_path(File.dirname(__FILE__) + '/../spec_helper')
   2  
   3  
   4  describe "Product" do
   5    @@valid_product_attributes = { 
   6        :name         => 'WTF',
   7        :description  => 'LOL',
   8        :price        => '10.0',
   9        :tax          => '22.0'  }
  10  
  11    
  12    before(:each) do
  13  
  14    end
  15  
  16    it "should create a new instance given valid attributes" do
  17      Product.create!(@@valid_product_attributes)
  18    end
  19    
  20    @@valid_product_attributes.each do |name, value|
  21      it "should not allow blank #{name}" do
  22        lambda do
  23          Product.create!(@@valid_product_attributes.except(name))
  24        end.should raise_error(ActiveRecord::RecordInvalid)
  25      end
  26    end
  27  end

You can easily extract video metadata into a hash with mplayer and Ruby:

   1  class Metadata
   2    
   3    def self.get(file)
   4      command  = "mplayer -vo null -ao null -frames 0 -identify #{file}"
   5      metadata = nil
   6      
   7      Open3.popen3(command) do |input, output, error|
   8        metadata = output.readlines.grep(/ID_.*/).collect {|name| name[3..name.length].split('=')}
   9        metadata = metadata.inject({}) {|hash, (key, value)| hash[key.to_sym] = value.chomp; hash}
  10      end
  11      
  12      return metadata
  13    end
  14    
  15  end

Then in an RSpec test do:

   1  it "should support 3gp" do
   2      metadata = Metadata.get("videos/sony_ericsson_k850i.3gp")
   3      
   4      metadata[:DEMUXER].should == 'mov'
   5      metadata[:VIDEO_FORMAT].should == 's263'
   6      metadata[:VIDEO_WIDTH].should == '176'
   7      metadata[:VIDEO_HEIGHT].should == '144'
   8    end

Note to self: metadata.demuxer would perhaps be a slightly better syntax.

   1  mplayer 123.avi -ss 1 -nosound -vo jpeg:outdir=. -frames 2

We use the -ss switch to jump to the first second of the video; specify the time in either seconds or hh:mm:ss. We tell mplayer that we want two frames with the -frames switch.

Make sure jpeg is in the list of supported video output formats:

   1  mplayer -vo help

First install the RSpec and ZenTest gem:

   1  $ sudo gem install rspec zentest

Next create the spec folder:

   1  $ cd project_folder
   2  $ mkdir spec

Save the following to spec/helper.rb:

   1  $LOAD_PATH.unshift File.dirname(__FILE__) + '/..'
   2  
   3  require 'rubygems'
   4  require 'spec'
   5  #require 'spec/rake/spectask' not needed, because ZenTest supports rspec now

Now create spec/transcoder_spec.rb, and add the following test to it:

   1  require File.dirname(__FILE__) + '/helper'
   2  require File.dirname(__FILE__) + '/../transcoder.rb'
   3  
   4  context "Transcoder" do
   5    setup do
   6      # Setup your stuff here
   7    end
   8    
   9    it "should support 3gp format" do
  10      Transcoder.convert("me_and_you.3gp").should == true
  11    end
  12  end

Let’s not forget the class we’re testing, put this code in lib/transcoder.rb:

   1  class Transcoder
   2    def initialize
   3    end
   4    
   5    def self.convert(file)
   6      return true
   7    end
   8  end

Note that autotest automatically looks for your code in the lib folder.

Now run the test with the zentest command:

   1  autotest

Change your files and autotest will run the test again.

Tip: Read Getting started with Autotest – Continuous Testing and Setting up autotest to use Growl on OSX for more information on how to increase your productivity.

First install Jabber::Simple:

   1  $sudo gem install xmpp4r-simple -y

On OSX you might get this error when installing xmpp4r-simple and the rdoc dependency:

   1  make
   2  gcc -I. -I/usr/local/lib/ruby/1.8/i686-darwin8.10.3 -I/usr/local/lib/ruby/1.8/i686-darwin8.10.3 -I.  -fno-common -g -O2  -fno-common -pipe -fno-common  -c callsite.c
   3  gcc -I. -I/usr/local/lib/ruby/1.8/i686-darwin8.10.3 -I/usr/local/lib/ruby/1.8/i686-darwin8.10.3 -I.  -fno-common -g -O2  -fno-common -pipe -fno-common  -c rcovrt.c
   4  cc -dynamic -bundle -undefined suppress -flat_namespace  -L"/usr/local/lib" -o rcovrt.bundle callsite.o rcovrt.o  -lruby  -lpthread -ldl -lobjc  
   5  /usr/bin/ld: /usr/lib/gcc/i686-apple-darwin8/4.0.1/../../../libpthread.dylib unknown flags (type) of section 6 (__TEXT,__dof_plockstat) in load command 0
   6  /usr/bin/ld: /usr/lib/gcc/i686-apple-darwin8/4.0.1/../../../libdl.dylib unknown flags (type) of section 6 (__TEXT,__dof_plockstat) in load command 0
   7  /usr/bin/ld: /usr/lib/gcc/i686-apple-darwin8/4.0.1/../../../libobjc.dylib load command 9 unknown cmd field
   8  /usr/bin/ld: /usr/lib/gcc/i686-apple-darwin8/4.0.1/../../../libSystem.dylib unknown flags (type) of section 6 (__TEXT,__dof_plockstat) in load command 0
   9  /usr/bin/ld: /usr/lib/libSystem.B.dylib unknown flags (type) of section 6 (__TEXT,__dof_plockstat) in load command 0
  10  collect2: ld returned 1 exit status
  11  make: *** [rcovrt.bundle] Error 1

Simply install XCode 3 to make the error go away, then run this code to start the bot—warning the bot will execute the message body, for example “ls -la”, on the system:

   1  require 'rubygems'
   2  require 'xmpp4r-simple'
   3  
   4  include Jabber
   5  #Jabber::debug = true
   6  
   7  jid = 'user@server.com'
   8  pass = 'password'
   9  
  10  jabber = Simple.new(jid, pass)
  11  
  12  loop do
  13    messages = jabber.received_messages
  14    messages.each do |message| 
  15      body = message.body if message.type == :chat
  16      
  17      process = IO.popen(body)
  18      result = process.readlines
  19      
  20      jabber.deliver('some.user@gmail.com', result)
  21    end
  22        
  23    sleep 1
  24  end

To use GTalk from another domain than gmail, you need to edit the Jabber::Simple source code…