Test::Unit GUI's fail for IO.popen?

I have come across a test case which breaks both GUI TestRunners, but
not the Console TestRunner.  The trouble appears to be the use of an
IO.pipe to capture output for testing.

The Fox runner will come up, but as soon as I hit the "run" button it
dies and I am left with,

  X Fatal error.
  Aborted

The Gtk runner begins running immediately(?!) and fails with

  Gdk-ERROR **: X connection to :0.0 broken (explicit kill or server shutdown).

I checked .xsession-errors and tried running in debug mode, but neither
provided any further diagnostics.

The following is a sample mobility test which demonstrates the failure -- at
least for my ruby-1.6.7/testunit-CVS/gtk-0.27/fxruby-1.0.3/i686-linux combination.
The test file will invoke the Console runner (via unit.rb's at_exit trick)
unless you pass it a command line argument, e.g., "f" or "g",

<file name="CmdLineOptsMT.rb">

 require 'test/unit'
 require 'CmdLineOpts'

 class CmdLineOptsMT < Test::Unit::TestCase
  def testUsage
   optionParser = CmdLineOpts.instance
   optionParser.addOption('unchangedParm', nil, -5, true){ |arg| arg.to_f }
   optionParser.processOptions
   inPipe,outPipe = IO.pipe
   if fork # parent process catches stdout from child
    outPipe.close
    usage = inPipe.read
    inPipe.close
    Process.wait
   else # child process throws usage to parent
    inPipe.close
    $stdout = outPipe
    optionParser.usage
    outPipe.close
    exit 0
   end
   assert(usage.include? " -h|--help\n")
   assert(usage.include? "--unchangedParm [-5]\n")
  end
 end

 if $0 == __FILE__ then
  case ARGV[0]
  when /^G/i
   require 'test/unit/ui/gtk/testrunner'
   Test::Unit::UI::GTK::TestRunner.run CmdLineOptsMT
  when /^F/i
   require 'test/unit/ui/fox/testrunner'
   Test::Unit::UI::Fox::TestRunner.run CmdLineOptsMT
  end
 end

</file>

The code under test is merely a convenient wrapper for getoptlong
inspired by the Pragmatic Programmer book, viz,

<file name="CmdLineOpts.rb">

 # In the spirit of "once and only once" we make a wrapper
 # to GetoptLong so that we only need to define options
 # in one spot.  The wrapper takes care of creating accessors,
 # setting default values, passing the options array to GetoptLong,
 # and creates a usage method.  -- Bill Wood and Bil Kleb

 require 'singleton'
 require 'getoptlong'

 class CmdLineOpts < Hash

  include Singleton

  def initialize
   super
   addOption('help', 'h'){CmdLineOpts.instance.usage; exit 1}
  end
  def addOption(longName, shortName=nil, defaultValue=nil,
                needsArgument=false, &action)
   store longName, Option.new(longName, shortName, defaultValue,
                              needsArgument, action)
  end
  def processOptions
   optionArray = Array.new
   each_value { |opt| optionArray.push opt.to_a }
   GetoptLong.new(*optionArray).each do |foundOption, arg|
    each{ |name, opt| opt.execute(arg) if foundOption.include? name }
   end
  end
  def usage
   puts "Usage: #{File.basename $0}"
   sort.each{ |key,opt| puts opt }
  end
  def [] (key)
   super(key).value
  end
  def []= (key, object)
   fetch(key).value = object
  end

 private

  class Option

   attr_reader :shortName
   attr_accessor :value

   def initialize( longName, shortName, defaultValue, needsArgument, action )
    @longName, @shortName = longName, shortName
    @needsArgument, @action = needsArgument, action
    @value = defaultValue
   end
   def execute(arg=nil)
    @value = @action.call arg
   end
   def to_s
    string = "       "
    string += (@shortName ? "-#@shortName|" : "   ") + "--#@longName"
    string += " [#{@value}]" if @value
    string
   end
   def to_a
    a = ['--'+@longName]
    a.push '-'+@shortName if @shortName
    a.push @needsArgument ?
           GetoptLong::REQUIRED_ARGUMENT : GetoptLong::NO_ARGUMENT
   end
  end
 end

</file>

-- 
Bil Kleb
NASA Langley Research Center
Hampton, Virginia, USA