Forward non-positive arg keys

This updates the helper loader and output handler loader to forward
non-positive command-line argument keys, that are automatically inserted
by the Lua interpreter, to the helper and output handler, respectively.

busted/modules/helper_loader.lua

@@ -1,11 +1,13 @@
 local path = require 'pl.path'
 local hasMoon, moonscript = pcall(require, 'moonscript')
+local utils = require 'busted.utils'
 
 return function()
   local loadHelper = function(busted, helper, options)
-    local old_arg = arg
+    local old_arg = _G.arg
     local success, err = pcall(function()
-      arg = options.arguments
+      utils.copy_interpreter_args(options.arguments)
+      _G.arg = options.arguments
       if helper:match('%.lua$') then
         dofile(path.normpath(helper))
       elseif hasMoon and helper:match('%.moon$') then

busted/modules/output_handler_loader.lua

@@ -1,10 +1,12 @@
 local path = require 'pl.path'
 local hasMoon, moonscript = pcall(require, 'moonscript')
+local utils = require 'busted.utils'
 
 return function()
   local loadOutputHandler = function(busted, output, options)
     local handler
 
+    utils.copy_interpreter_args(options.arguments)
     local success, err = pcall(function()
       if output:match('%.lua$') then
         handler = dofile(path.normpath(output))

busted/utils.lua

@@ -1,4 +1,15 @@
 return {
+  copy_interpreter_args = function(arguments)
+    -- copy non-positive command-line args auto-inserted by Lua interpreter
+    if arguments and _G.arg then
+      local i = 0
+      while _G.arg[i] do
+        arguments[i] = _G.arg[i]
+        i = i - 1
+      end
+    end
+  end,
+
   split = require 'pl.utils'.split,
 
   shuffle = function(t, seed)

spec/cl_spec.lua

@@ -301,7 +301,7 @@ describe('Test busted running standalone', function()
     assert.is_false(success)
   end)
 
-  it('tests running with via stdin', function()
+  it('tests running via stdin', function()
     local success, errcnt = executeLua('< spec/cl_standalone.lua')
     assert.is_false(success)
     assert.is_equal(3, errcnt)