IMG_9177, from lassekoskela.

]]> http://www.marekj.com/2008/08/img_9177/feed/ http://www.marekj.com/2008/07/tinytutorial-yielding-value-back-to-block/ http://www.marekj.com/2008/07/tinytutorial-yielding-value-back-to-block/#comments Mon, 14 Jul 2008 22:43:19 +0000 marekj http://www.marekj.com/?p=118 UPDATE. I guess I will just write on gist.github.com

irb(main):003:0> class Bla; end
=> nil
irb(main):004:0> b = Bla.new
=> #
irb(main):005:0> b.class
=> Bla
irb(main):006:0> b.new
NoMethodError: undefined method `new' for #
irb(main):007:0> c = Class.new
=> #
irb(main):008:0> c.new
=> #<#:0x2b5f570>
irb(main):009:0> c.class
=> Class

So, an interesting thing happened here. The variable ‘c’ is an instance of a class Class and you can create another instance of ‘c’ by calling ‘c.new’ however ‘b’ instance of class Bla tells us ‘undefined method’ when we try to do b.new.

Consider this from Ruby for Rails book:

Classes are objects; specifically, they are instances of the class Class (…) When you instantiate the class Class—when you create an instance of it—you’ve created a class. That class, in turn, can create instances of its own (…) class objects are usually stored in constants (…) in the previous example, however, we’ve stored a class in a regular variable When we call the .new method, we send the message new to the class through that variable

And yes, there is a paradox here. The class Class is an instance of itself; that is, it’s a Class object. And there’s more. Remember the class Object? Well, Object is a class … but classes are objects. So Object is an object. And Class is a class. And Object is a class, and Class is an object.

Which came first? How can the class Class be created unless the class Object already exists? But how can there be a class Object (or any other class) until there’s a class Class of which there can be instances?

The best way to deal with this paradox, at least for now, is to ignore it. Ruby has to do some of this chicken-or-egg stuff in order to get the class and object system up and running—at which point the circularity and paradoxes don’t matter. In the course of programming, you just need to know that classes are objects, and the class of which class-objects are instances is the class called Class.

So Ruby 1.8.9-26 bundles gem 0.9.4. I did not update the gem system (I am not sure if I should or not) and then I did ‘gem install watir’. Here is what we get at the prompt.

C:\Users\marekj>gem -v
0.9.4

C:\Users\marekj>gem install watir
Bulk updating Gem source index for: http://gems.rubyforge.org
Install required dependency win32-process? [Yn]  Y
Install required dependency windows-pr? [Yn]  Y
Install required dependency windows-api? [Yn]  Y
Install required dependency win32-api? [Yn]  Y
Select which gem to install for your platform (i386-mswin32)
 1. win32-api 1.1.0 (ruby)
 2. win32-api 1.1.0 (x86-mswin32-60)
 3. win32-api 1.0.6 (ruby)
 4. win32-api 1.0.6 (x86-mswin32-60)
 5. Skip this gem
 6. Cancel installation
> 2
Install required dependency activesupport? [Yn]  Y
Successfully installed watir-1.5.6
Successfully installed win32-process-0.5.9
Successfully installed windows-pr-0.8.6
Successfully installed windows-api-0.2.3
Successfully installed win32-api-1.1.0-x86-mswin32-60
Successfully installed activesupport-2.1.0
Installing ri documentation for watir-1.5.6…
Installing ri documentation for win32-process-0.5.9…
Installing ri documentation for windows-pr-0.8.6…
Installing ri documentation for windows-api-0.2.3…
Installing ri documentation for win32-api-1.1.0-x86-mswin32-60…
Installing ri documentation for activesupport-2.1.0…
Installing RDoc documentation for watir-1.5.6…
Installing RDoc documentation for win32-process-0.5.9…
Installing RDoc documentation for windows-pr-0.8.6…
Installing RDoc documentation for windows-api-0.2.3…
Installing RDoc documentation for win32-api-1.1.0-x86-mswin32-60…
Installing RDoc documentation for activesupport-2.1.0…

C:\Users\marekj>

I am just not sure what activesupport is needed for here. which gem needs it? (I will look at gemspecs)

So to summarize - to install watir 1.5.6 I also needed to install 4 more gems: windows-pr-0.8.6, windows-api-0.2.3, win32-api-1.1.0 (x86-mswin32-60) and activesupport-2.1.0

we’ll dig deeper to make sure installation went great.
next unit tests.

and the first try ‘puch help I got the error: couldn’t find HOME environment — expanding `~’ (ArgumentError). Looks like windows problem… so on my machine I changed to:

Home = File.expand_path(ENV['USERPROFILE'])

# C:\ruby\lib\ruby\gems\1.8\gems\punch-0.0.2\bin\punch:313

all is well.

# lets say ARGV has 3 items [1, 2, 3]
# the following:
a, b, c = ARGV
# will make this
#=> a=1, b=2, c=3

I didn’t know you can do this. I just ready it in one of the examples somewhere and I can’t find it.
Nice way of procesing not only ARGV but other arrays.

#So, this is how I can ship my data in Watir scripts.
# Write out:
ARGV.clear
ARGV << 'a1' << 'b2' << 'c3' # 

# read from:
a, b, c = ARGV
# of course I could use main gem or other option parsers
# but ARGV is a good simple choice

class Person
  def say_hello
    puts 'how do you do.'
  end
end

class Student  Person
end

class Student    # reopening class
  # Assuming Person has a say_hello method...
  alias :say_hi :say_hello #this calls super
  def say_hello
    puts "Hi, there."
  end
  def formal_greeting
    # Say hello the way my superclass would.
    say_hi
  end
end
Student.new.formal_greeting

So positioning alias above say_hello definition ensures your call goes up to super class. Am I reading this correctly? if so then this is a nice strategy for designing watir tests depending on configurations needed for your test objects.

like this:

I like this solution for my test framework. I have been thinking of making a small change to my snagit screenshot.
Basically be default I want it to take a screenshot of a :desktop but I also want it to snag a webpage with scrolling.
I still need to understand why the how.class is compared to String and not to Symbol.

And on another note I need to start watir.testr.us page for all watir related info in one place. - The Place To Put Things is a constant challenge, it seems.

# Runtime Test Housekeeping place
module TestRun

  # at runtime takes a screenshot of the desktop and saves it in log dir.
  # you must install win32screenshot gem and RMagic package for this to work.
  def self.screenshot(context=nil)
    if $testrun[:screenshot] == true
      # prevent runtime error when screenshot gem and RMagic are not installed on client machine.
      begin
        require ‘win32screenshot’
        require ‘RMagick’
        width, height, bitmap = Win32::Screenshot.desktop
        imglist = Magick::ImageList.new
        imgl = imglist.from_blob(bitmap)
        time_stamp_s = Time.new.strftime(’%m%d_%H%M_%S’)
        screenshot_filename = context ? “#{time_stamp_s}_#{context}.png” : “#{time_stamp_s}.png”
        imgl.write(File.join(logpath,screenshot_filename))
        $log.info(”Screenshot captured: #{screenshot_filename}”)
      rescue Exception => ex
        $log.error(”TestRun.screenshot(#{context} — #{ex}”)
      end

    end

  end

end

#usage
TestRun.screenshot() # => makes a MMDD_HHMM_SS.png file
TestRun.screenshot(’blabla’) # appends the string to filename.

The above is an older solution, I’ve had it working for a while but now it has stopped after I upgraded rubygems system. It still works on my other test machines but not on my primary box.

Instead I have installed snagit 8 and I am using it for web page capture. it’s better, definitely better with the COM interface.
I just wanted to post the code here in case I need to refer to it again in the future. (note: logpath method returns path to log directory. The global $testrun hash holds runtime options for the test framework.

Thanks win32screenshot and thanks RMagick, it was fun using it, moving on to snagit OLE interface.

UPDATE:
Here is my current reimplementation using snagit

def self.screenshot(context=nil)
    if $testrun[:screenshot] == true #runtime options guard access

      begin
        require ‘win32ole’
        snagit = WIN32OLE.new(’Snagit.ImageCapture’)
        time_stamp_s = Time.new.strftime(’%m%d_%H%M_%S’)
        screenshot_filename = context ? “#{time_stamp_s}_#{context}” : “#{time_stamp_s}”
        # config input
        snagit.Input = 0 #desktop
        #configure output
        snagit.Output = 2 #file
        snagit.OutputImageFile2.FileType = 5 #:png
        snagit.OutputImageFile2.FileNamingMethod = 1 # fixed #
        #location
        snagit.OutputImageFile2.Directory = logpath   # set directy where filename will be saved
        snagit.OutputImageFile2.Filename = screenshot_filename
        # do the duty
        snagit.Capture
        # wait for capture to complete
        until snagit.IsCaptureDone do
          sleep 0.5
        end
        $log.info(”Screenshot captured: #{screenshot_filename}”)
      rescue Exception => ex
        $log.error(”TestRun.screenshot(#{context} — #{ex}”)
      end
    end
  end

The above works pretty well. my next thing is to implement taking a screenshot of a page with setting Input active window and scrolling it. It’ll be fun.

class ThreeStepTest
  attr_accessor :context

  # config context for the test
  def initizlie(context)
     @context = context
  end

  # act one
  def set_request
    # given context configure the page with data.
    # Delegate to watir implementer here to send data to the page.
  end

  # act two
  def submit_request
    # delegate to watir to click on a page to submit form or request next page
  end

  # act three
  def verify_response
    # get context
    @context =
  end
end

class Context
  attr_accessor :given, :expected, :actual

end

the set_request occurs in a Given Context which was created by the previous verify_response.

So a test scenario can be constructed a series of those 3 acts. Context has a :given as a precondition to start with, :expected and :actual.

Anyway, this is just some thinking about constructing Watir framework