refactoring: update definition of "register_driver" method

Before the commit the "register_driver" method was defined in two
places: abstract.lua and init.lua. This is not good. So, now it
has been fixed.

Author: LeonidVas

queue/abstract.lua

@@ -669,12 +669,4 @@ setmetatable(queue.stat, {
     }
 )
 
-queue.register_driver = function(driver_name, tube_ctr)
-    if type(tube_ctr.create_space) ~= 'function' or
-       type(tube_ctr.new) ~= 'function' then
-        error('tube control methods must contain functions "create_space" and "new"')
-    end
-    queue.driver[driver_name] = tube_ctr
-end
-
 return setmetatable(queue, { __index = method })

queue/init.lua

@@ -1,13 +1,17 @@
 local queue = nil
+
+local function register_driver(driver_name, tube_ctr)
+    if type(tube_ctr.create_space) ~= 'function' or
+        type(tube_ctr.new) ~= 'function' then
+        error('tube control methods must contain functions "create_space"'
+              .. ' and "new"')
+    end
+    queue.driver[driver_name] = tube_ctr
+end
+
 queue = setmetatable({
     driver = {},
-    register_driver = function(driver_name, tube_ctr)
-        if type(tube_ctr.create_space) ~= 'function' or
-           type(tube_ctr.new) ~= 'function' then
-            error('tube control methods must contain functions "create_space" and "new"')
-        end
-        queue.driver[driver_name] = tube_ctr
-    end,
+    register_driver = register_driver,
 }, { __index = function() print(debug.traceback()) error("Please run box.cfg{} first") end })
 
 if rawget(box, 'space') == nil then
@@ -34,6 +38,7 @@ if rawget(box, 'space') == nil then
     end
 else
     queue = require 'queue.abstract'
+    queue.register_driver = register_driver
     queue.start()
 end
 

t/140-register-driver-after-cfg.t

@@ -0,0 +1,43 @@
+#!/usr/bin/env tarantool
+local tap = require('tap')
+local tnt = require('t.tnt')
+
+local test = tap.test('test driver register')
+test:plan(2)
+
+local mock_tube = {
+    create_space = function() end,
+    new = function() end
+}
+
+-- As opposed to 001-tube-init.t, queue initialization
+-- and driver registration are done after cfg().
+local function check_driver_register()
+    tnt.cfg()
+    local queue = require('queue')
+    queue.register_driver('mock', mock_tube)
+    test:is(queue.driver.mock, mock_tube, 'driver has been registered')
+
+    local standart_drivers = {
+        'fifo',
+        'fifottl',
+        'limfifottl',
+        'utube',
+        'utubettl'
+    }
+    local check_standart_drivers = true
+
+    for _, v in pairs(standart_drivers) do
+        if queue.driver[v] == nil then
+            check_standart_drivers = false
+            break
+        end
+    end
+
+    test:ok(check_standart_drivers, 'standard drivers are defined')
+end
+
+check_driver_register()
+
+tnt.finish()
+os.exit(test:check() and 0 or 1)