diff --git a/lua/apisix/core/id.lua b/lua/apisix/core/id.lua
index ac3e368e..27042733 100644
--- a/lua/apisix/core/id.lua
+++ b/lua/apisix/core/id.lua
@@ -1,6 +1,7 @@
 local log = require("apisix.core.log")
 local uuid = require('resty.jit-uuid')
 local smatch = string.match
+local open = io.open
 
 
 local prefix = ngx.config.prefix()
@@ -15,7 +16,7 @@ end
 
 
 local function read_file(path)
-    local file = io.open(path, "rb") -- r read mode and b binary mode
+    local file = open(path, "rb") -- r read mode and b binary mode
     if not file then
         return nil
     end
@@ -27,7 +28,7 @@ end
 
 
 local function write_file(path, data)
-    local file = io.open(path ,"w+")
+    local file = open(path ,"w+")
     if not file then
         return nil, "failed to open file[" .. path .. "] for writing"
     end
@@ -46,7 +47,7 @@ function _M.init()
     end
 
     apisix_uid = uuid.generate_v4()
-    log.warn("not found apisix uid, generate a new one: ", apisix_uid)
+    log.notice("not found apisix uid, generate a new one: ", apisix_uid)
 
     local ok, err = write_file(uid_file_path, apisix_uid)
     if not ok then
diff --git a/lua/apisix/core/utils.lua b/lua/apisix/core/utils.lua
index 2d9bc500..2e243f77 100644
--- a/lua/apisix/core/utils.lua
+++ b/lua/apisix/core/utils.lua
@@ -1,4 +1,3 @@
-local log = require("apisix.core.log")
 local open = io.open
 
 
diff --git a/t/core-id.t b/t/core-id.t
new file mode 100644
index 00000000..576ccb87
--- /dev/null
+++ b/t/core-id.t
@@ -0,0 +1,26 @@
+use t::APISix 'no_plan';
+
+repeat_each(1);
+no_long_string();
+no_root_location();
+log_level("info");
+
+run_tests;
+
+__DATA__
+
+=== TEST 1: sanity
+--- config
+    location /t {
+        content_by_lua_block {
+            local core = require("apisix.core")
+
+            ngx.say("uid: ", core.id.get())
+        }
+    }
+--- request
+GET /t
+--- response_body_like eval
+qr/uid: [0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}/
+--- error_log
+not found apisix uid, generate a new one
diff --git a/t/core-utils.t b/t/core-utils.t
new file mode 100644
index 00000000..de570b25
--- /dev/null
+++ b/t/core-utils.t
@@ -0,0 +1,25 @@
+use t::APISix 'no_plan';
+
+repeat_each(1);
+no_long_string();
+no_root_location();
+log_level("info");
+
+run_tests;
+
+__DATA__
+
+=== TEST 1: sanity
+--- config
+    location /t {
+        content_by_lua_block {
+            local get_seed = require("apisix.core.utils").get_seed_from_urandom
+
+            ngx.say("random seed ", get_seed())
+            ngx.say("twice: ", get_seed() == get_seed())
+        }
+    }
+--- request
+GET /t
+--- response_body_like eval
+qr/random seed \d+\ntwice: false/