#
# capturestdout.rb
# Capture StdOut from ruby functions/classes, e.g. TestCase messages.
#
# Author:: David Muir <david.muir@rockstarnorth.com>
# Date:: 30 January 2008
#
# References:
#   * http://stefankst.net/2007/06/05/capture-standard-output-in-ruby/
#

#-----------------------------------------------------------------------------
# Uses
#-----------------------------------------------------------------------------
require 'pipeline/log/log'
require 'stringio'

module Pipeline
module OS

    #
    # == Description
    # Yields Ruby block with stdout captured to a StringIO object and returns
    # the resulting string.
    #
    # == Example Usage
    #    out = Pipeline::OS.capture_stdout do
    #      puts "Hello, World!"
    #    end
    #    puts out
    #
    def self.capture_stdout
    
		rootlog = LogSystem::instance.rootlog
        rootlog.debug( "Pipeline::OS.capture_stdout : capturing $stdout." )
        
        # Save old $stdout IO stream, and create new String IO stream.
        old_stdout = $stdout
        out = StringIO.new()
        
        # Set $stdout to our new StringIO stream.
        $stdout = out
        begin
        
            # This invokes the calling scope's code block.
            yield
        
        rescue Exception => ex
            
            rootlog.error( "Pipeline::OS.capture_stdout exception: #{ex.message}." )
			rootlog.error( "  Backtrace: " )
			ex.backtrace.each do |msg|
				rootlog.error( "    #{msg}" )
            end
        ensure
        
            # Ensure that we restore $stdout to previous IO stream.
			rootlog.debug( "Pipeline::OS.capture_stdout : restoring $stdout." )
            $stdout = old_stdout
        end       
        
        out.string
    end

end # OS module
end # Pipeline module

# End of capturestdout.rb