test: also lint the test helpers (#2252)

Close #2215
diff --git a/t/lib/server.lua b/t/lib/server.lua
index 68ba81a..c9e89e9 100644
--- a/t/lib/server.lua
+++ b/t/lib/server.lua
@@ -154,7 +154,8 @@
             ngx.exit(400)
         end
 
-        if span.localEndpoint.serviceName ~= 'APISIX' and span.localEndpoint.serviceName ~= 'apisix' then
+        if span.localEndpoint.serviceName ~= 'APISIX'
+          and span.localEndpoint.serviceName ~= 'apisix' then
             ngx.exit(400)
         end
 
@@ -205,7 +206,9 @@
     local args = ngx.req.get_uri_args()
     local resName = args.resName
     if resName == '/hello' or resName == '/wolf/rbac/custom/headers' then
-        ngx.say(json_encode({ok=true, data={ userInfo={nickname="administrator",username="admin", id="100"} }}))
+        ngx.say(json_encode({ok=true,
+                            data={ userInfo={nickname="administrator",
+                                username="admin", id="100"} }}))
     else
         ngx.status = 401
         ngx.say(json_encode({ok=false, reason="no permission to access"}))
@@ -220,7 +223,8 @@
         ngx.exit(0)
     end
 
-    ngx.say(json_encode({ok=true, data={ userInfo={nickname="administrator", username="admin", id="100"} }}))
+    ngx.say(json_encode({ok=true,
+                        data={ userInfo={nickname="administrator", username="admin", id="100"} }}))
 end
 
 function _M.wolf_rbac_change_pwd()
@@ -237,7 +241,8 @@
 
 function _M.wolf_rbac_custom_headers()
     local headers = ngx.req.get_headers()
-    ngx.say('id:' .. headers['X-UserId'] .. ',username:' .. headers['X-Username'] .. ',nickname:' .. headers['X-Nickname'])
+    ngx.say('id:' .. headers['X-UserId'] .. ',username:' .. headers['X-Username']
+            .. ',nickname:' .. headers['X-Nickname'])
 end
 
 function _M.websocket_handshake()
diff --git a/t/lib/test_admin.lua b/t/lib/test_admin.lua
index dc245c3..ac6d22e 100644
--- a/t/lib/test_admin.lua
+++ b/t/lib/test_admin.lua
@@ -16,6 +16,7 @@
 --
 local http              = require("resty.http")
 local json              = require("cjson.safe")
+local core              = require("apisix.core")
 local aes               = require "resty.aes"
 local ngx_encode_base64 = ngx.encode_base64
 local str_find          = string.find
diff --git a/utils/check-lua-code-style.sh b/utils/check-lua-code-style.sh
index 6cb80d3..2dfff59 100755
--- a/utils/check-lua-code-style.sh
+++ b/utils/check-lua-code-style.sh
@@ -19,7 +19,7 @@
 
 set -ex
 
-luacheck -q apisix
+luacheck -q apisix t/lib
 
 find apisix -name '*.lua' -exec ./utils/lj-releng {} + > \
     /tmp/check.log 2>&1 || (cat /tmp/check.log && exit 1)