test: fix the excess upvalues: yaml error in helpers

storage_wait_follow_f() function from luatest_helpers/vtest.lua
mentioned globally defined yaml library.

Fix it.

NO_DOC=test

Author: sergepetrenko

.luacheckrc

@@ -36,6 +36,7 @@ local test_rules = {
         '113/ivtest',
         '113/ivutil',
         '113/iwait_timeout',
+        '113/iyaml',
     }
 }
 

test/instances/router.lua

@@ -13,6 +13,7 @@ _G.ivtest = require('test.luatest_helpers.vtest')
 _G.ivconst = require('vshard.consts')
 _G.iverror = require('vshard.error')
 _G.iwait_timeout = _G.ivtest.wait_timeout
+_G.iyaml = require('yaml')
 
 -- Do not load entire vshard into the global namespace to catch errors when code
 -- relies on that.

test/instances/storage.lua

@@ -13,6 +13,7 @@ _G.ivconst = require('vshard.consts')
 _G.ivutil = require('vshard.util')
 _G.iverror = require('vshard.error')
 _G.ivtest = require('test.luatest_helpers.vtest')
+_G.iyaml = require('yaml')
 
 _G.iwait_timeout = _G.ivtest.wait_timeout
 

test/luatest_helpers/vtest.lua

@@ -4,7 +4,6 @@ local cluster = require('test.luatest_helpers.cluster')
 local fio = require('fio')
 local fiber = require('fiber')
 local uuid = require('uuid')
-local yaml = require('yaml')
 local vcfg = require('vshard.cfg')
 local vrepset = require('vshard.replicaset')
 local log = require('log')
@@ -552,7 +551,7 @@ local function storage_wait_follow_f(id)
         do return end
     ::retry::
         if ifiber.clock() > deadline or status == 'stopped' then
-            ilt.fail(yaml.encode({
+            ilt.fail(iyaml.encode({
                 err = last_err,
                 dst_id = id,
                 replication_info = box.info.replication,