From: Joe Van Dyk <joevandyk@...>
Date: 2005-06-09T07:21:35+09:00
Subject: Re: Test-Driven Development in GUIs

On 6/8/05, Joe Van Dyk <joevandyk@gmail.com> wrote:
> On 6/7/05, Joe Van Dyk <joevandyk@gmail.com> wrote:
> > Hi,
> >
> > Anyone have any tips for writing GUIs in Ruby (using Tk, for example)
> > using a TDD approach?
> >
> > A google search gave me
> > http://approximity.com/ruby/rubytk.html#testfirst, which claims that
> > some guy is writing a book on TDD for GUIs, using Ruby/Tk as preferred
> > language/toolkit.  That section links to
> > http://www.c2.com/cgi/wiki?TestFirstUserInterfaces, while informative,
> > doesn't contain any information that I can see on a book.
> >
> > Say, for the purposes of this discussion, say that you had a small Tk
> > application that monitored the status of ten websites.  If the website
> > was up and was active and performing well, the GUI would display a
> > "Working!" message and perhaps showed data about the site (latency,
> > bandwidth, whatever).  The GUI could also display graphs of
> > uptime/downtime, view history reports, and moderately complex GUI
> > stuff like that.
> >
> > How would you go about testing that GUI application?  There's a strong
> > chance that if I get some good ideas from my head and from this
> > discussion, that I'd write that application and also write a HOWTO on
> > TDD with GUIs.
> >
> > Thanks,
> > Joe
> >
> 
> Here's a very simple example of a quick UI app that's unit tested.
> Comments appreciated.
> 
> If you run the application like 'ruby file.rb test', the tests will
> get run.  If you run it like 'ruby file.rb', the gui will be
> displayed.  In a real application, the tests would be in their own
> file, of course.
> 
> As I do more research, I'll post more examples.

Here's another iteration, this time the result is being displayed to a
TkLabel.  The tests check to see if the label has the correct value.

So, when testing GUIs, is it good practice to have all the (tested)
widgets be available through attr_accessor (or attr_readers)?  How
else can you test them?

require 'tk'
require 'test/unit'

class App
  attr_accessor :sum, :inc_button, :display_button, :power_2_button, 
  :output_label

  def initialize
    @sum = TkVariable.new
    @sum.value = 0

    root = TkRoot.new :title => 'my app' 

    @inc_button = TkButton.new root
    @inc_button.text = "Increment"
    @inc_button.command = proc { inc }
    @inc_button.pack :expand => true

    @power_2_button = TkButton.new(root)
    @power_2_button.text = "Power of 2"
    @power_2_button.command = proc { power2 }
    @power_2_button.pack :expand => true

    description_label = TkLabel.new
    description_label.text = "Result:"
    description_label.pack :expand => true
    @output_label = TkLabel.new
    @output_label.textvariable = @sum
    @output_label.pack :expand => true
  end

  def inc
    @sum.value = @sum.value.to_i + 1
  end

  def power2
    @sum.value = @sum.value.to_i * @sum.value.to_i
  end
end


class TestApp < Test::Unit::TestCase
  def result(app)
    app.output_label.text.to_i
  end

  def testInc
    app = App.new

    assert_equal 0, result(app)

    app.inc_button.invoke
    assert_equal 1, result(app)

    app.inc_button.invoke
    assert_equal 2, result(app)
  end

  def testPower2
    app = App.new

    assert_equal 0, result(app)

    app.power_2_button.invoke
    assert_equal 0, result(app)

    app.inc_button.invoke
    assert_equal 1, result(app)

    app.power_2_button.invoke
    assert_equal 1, result(app)

    app.inc_button.invoke
    assert_equal 2, result(app)

    app.power_2_button.invoke
    app.power_2_button.invoke
    assert_equal 16, result(app)
  end
end

if ARGV[0] != 'test'
  App.new
  Tk.mainloop
  exit
end