niczsoft

This article is indirect translation of Cucumber – obsluga kilku sesji – polish version (from andrzejsliwa.com devblog).

Most of standard testing related tasks can be achieved in a simple way using the default steps from Cucumber. By assumption Cucumber is for functional testing, but it can also be used to implement integration test. This is especially useful when we want test interaction between users, when they should get on-line notifications – and this should be tested without login/logout functionality, like in shout box which was popular some time ago.

When using integration tests you could use block open_session:

def login(user)
  open_session do |sess|
    sess.extend(CustomDsl)
    u = users(user)
    sess.https!
    sess.post "/login", :username => u.username, :password => u.password
    assert_equal '/welcome', path
    sess.https!(false)
  end
end

But in the case of cucumber which is based on the steps it was necessary to find a solution that is suited to the form in which scenarios are created.

So I have asked my friend Andrzej Sliwa to write an example code, this is the example:

module ActionController
  module Integration
    class Session
      def switch_session_by_name(name)
        if @sessions_by_name.nil?
          @sessions_by_name = { :default => @response.session.clone }
        end
        @sessions_by_name[name.to_sym] ||= @sessions_by_name[:default].clone
        @response.session = @sessions_by_name[name.to_sym]
      end
    end
  end
end

Given /^session name is "([^\"]*)"$/ do |name|
  switch_session_by_name(name)
end

Use of this mechanism is trivially easy to perform the following step:

Given session name is "guest no 1 session"

g

In this case, a named session is created which is not dependent on others (including the default). Access to default session is called by using the default name:

Given session name is "default"

You can always get back to named session using the same name as before, the state of it will be persisted for you.

More details on Integration tests: http://guides.rubyonrails.org/testing.html#integration-testing-examples

There are many ways to iterate in ruby, many methods, but going back to assembler roots of mine I found another one:

>> a=[1,2,3]
=> [1, 2, 3]
>> begin puts a.shift; raise unless a.blank?; rescue; retry; end
1
2
3
=> nil

This code is only prof of concept, it should not be used for iterations, by example if it would be used without prior initialization of “a” variable it would be an endless loop as on exception “NameError” it will retry in endless loop.

There are other places where this could be used, but even possible retry should not be used without some kind of endless loop protection like:

>> i=10; begin puts IO.read('some.file'); rescue; if i>0 then puts "#{i} ..."; i-=3; sleep 1; retry; end; end
10 ...
9 ...
8 ...
7 ...
some file created
=> nil

In this example a file was created during run of the command – on second console by just running “echo some file created > some.file”.

There are other ways to do the same, maybe not so cool like that above but probably most of developers will prefer something like:

>> 10.downto(1){|i| begin puts IO.read('some.file'); break; rescue; puts "#{i} ..."; sleep 3; end }
10 ...
9 ...
8 ...
some file created
=> nil

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There are few ways to have a class from a string, most know are:

• Kernel.const_get(‘User’)
• eval(‘User’)
• ‘User’.constantize

The order in which I have named them is important – a bit important, Kernel.const_get is 10 times faster then constantize and 5 times faster then eval.

The reason of such speed for Kernel.const_get is from it has to maintain list of all constants in the application, tests show it may even behave faster then storing names and Class mapping in a hash.

The difference is not big on simple calls to create just one or two classes, but on heavy loaded systems this might give some more percents of the hardware.

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Today I was coding just for fun … and wrote my own Capistrano script for deployment, during this I have found great way to invoke remote tasks.

The method is easy, add following code to your config/deploy.rb file:

set :sudo_call, ''
desc 'makes remote/rake calls to be executed with sudo'
task :use_sudo do
  set :sudo_call, 'sudo'
end

desc 'run rake task'
task :rake do
  ARGV.values_at(Range.new(ARGV.index('rake')+1,-1)).each do |task|
    run "cd #{current_path}; #{sudo_call} RAILS_ENV=production rake #{task}"
  end
  exit(0)
end

desc 'run remote command'
task :remote do
  command=ARGV.values_at(Range.new(ARGV.index('remote')+1,-1))
  run "cd #{current_path}; #{sudo_call} RAILS_ENV=production #{command*' '}"
  exit(0)
end

desc 'run specified rails code on server'
task :runner do
  command=ARGV.values_at(Range.new(ARGV.index('runner')+1,-1))
  run "cd #{current_path}; RAILS_ENV=production script/runner '#{command*' '}'"
  exit(0)
end

Now try your new tool with following commands:

cap rake db:migrate
cap use_sudo rake db:migrate
cap remote "tail -n 10 log/production.log"
cap use_sudo remote cat /etc/passwd
cap runner p User.all
cap runner "User.all.each{ |u| p u }"

In the third call I have used parentheses to hide “-n” form Capistrano, because it is its parameter, to see whole list of Capistrano parameters call it with “cap –help”. For the last command I have used parentheses again because now it contained bash special characters.

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Lately netbeans remainded me about something that makes great marketing for Ruby on Rails – ability to create application in 10 minutes.

By example you can have a look on the netbeans tutorial. Everything looks great, sometimes You can even create the application in 10 minutes …

Lets think what You will get in this 10 minutes:

• Scaffold of application … without head or legs

Thats all, the application generated in 10 minutes does not have authentication, it does not have administrative part. Of course there is a lot of plugins, that helps to add functionality to Yours application. But wait a minute, authors of this plugins cant catch up stable rails.

Each few months we have new rails version, and each version is requiring application changes, this is endless. After You finish migration to newest rails, after You find new plugins there is new rails version – and the  wheel spins again.

Comparing to other applications rails is getting new releases at least twice offten, that would be good if it would have one stable base, but not, the base is changing each few months.

And what is the plan, four months after rails 2.3 we will have rails 3.0, it will be more like rails or maybe more like merb? Hopefully it will start slowing down a bit, as it requires now very big efforts to maintain application and keep it up todate.

Somebody would say “You can freeze rails, gems and plugins” – yes I can, but I can not freeze my developers, they will learn new rails version, and after one year I will have a team of experienced developers in rails 4.0 or even rails 5.0 and application with frozen reail 2.3 … and try to migrate when the core was rewritten three times during last year.

Assuming having steady framewoirk with “broken tables” like Java or less broken DJango makes a lot more work on begining, but development stacks are available, the documentation is more complete, and the major version changes once for few years, this allows developer to understand and modify application code even after ten years.

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