anchor.diff:  
   A test is first initialized before it is "executed":#background.running-tests.exec. <xref #fig..ruby_init> illustrates the initialization process "described below":#proc..ruby_init.
   
  -# The Verilog simulator initializes the Ruby interpreter by invoking the @$ruby_init;@ system task/function, whose parameters represent the command-line invocation of the Ruby interpreter. For example, one would specify @$ruby_init("ruby", "-w");@ in Verilog to achieve the same effect as specifying <pre>ruby -w</pre> at a command-prompt.
  +# The Verilog simulator initializes the Ruby interpreter by invoking the @$ruby_init;@ system task/function, whose parameters represent the command-line invocation of the Ruby interpreter. For example, one would specify @$ruby_init("ruby", "-w");@ in Verilog to achieve the same effect as running <pre>ruby -w</pre> at a command-prompt.
   # The Verilog simulator is paused and the Ruby interpreter is initialized with the arguments of the @$ruby_init;@ system task/function.
   # When the Ruby interpreter invokes the @Vpi::relay_verilog@ method, it is paused and the Verilog simulator is given control.
   
  
positive.code: 
  * "ScriptSim":http://www.nelsim.com is a Perl, Python, and Tcl/Tk interface to PLI.
  * "Verilog::Pli":http://www.veripool.com/verilog-pli.html is a Perl interface to PLI.
  * "JPLI":http://www.time-rover.com/jpli/ is a Java interface to PLI.
  
  
  h1(#background). Background
  
negative.code: <% end %>
  
  <% important "Before we continue..." do %>
  # Replace the contents of the file named <tt>counter_rspec_spec.rb</tt> with the source code shown in <xref #fig..counter_rspec_spec.rb>.
  # Replace the contents of the file named <tt>counter_xunit_spec.rb</tt> with the source code shown in <xref #fig..counter_xunit_spec.rb>.
  # Replace the contents of the files named <tt>counter_rspec_design.rb</tt> and <tt>counter_xunit_design.rb</tt> with the following code. This code defines the reset! method which resets our Verilog design. <code>
  def Counter.reset!
    reset.intVal = 1
  