diff --git a/tests/system-test/2-query/function_diff.py b/tests/system-test/2-query/function_diff.py
index 7d49f875d1d8b6a464de6bf167dc054502f5c21e..5e95510c1d7337cfe81850249a375d35ba307c7c 100644
--- a/tests/system-test/2-query/function_diff.py
+++ b/tests/system-test/2-query/function_diff.py
@@ -370,17 +370,17 @@ class TDTestCase:
         tdSql.query("select diff(st1+c1) from stb1 partition by tbname")
         tdSql.checkRows(190)
 
-        # # bug need fix 
+        # # bug need fix
         # tdSql.query("select diff(st1+c1) from stb1 partition by tbname slimit 1 ")
         # tdSql.checkRows(19)
         # tdSql.error("select diff(st1+c1) from stb1 partition by tbname limit 1 ")
 
 
-        # bug need fix 
+        # bug need fix
         tdSql.query("select diff(st1+c1) from stb1 partition by tbname")
         tdSql.checkRows(190)
 
-        # bug need fix 
+        # bug need fix
         # tdSql.query("select tbname , diff(c1) from stb1 partition by tbname")
         # tdSql.checkRows(199)
         # tdSql.query("select tbname , diff(st1) from stb1 partition by tbname")
@@ -388,7 +388,7 @@ class TDTestCase:
         # tdSql.query("select tbname , diff(st1) from stb1 partition by tbname slimit 1")
         # tdSql.checkRows(19)
 
-        # partition by tags 
+        # partition by tags
         # tdSql.query("select st1 , diff(c1) from stb1 partition by st1")
         # tdSql.checkRows(199)
         # tdSql.query("select diff(c1) from stb1 partition by st1")
@@ -488,4 +488,4 @@ class TDTestCase:
         tdLog.success("%s successfully executed" % __file__)
 
 tdCases.addWindows(__file__, TDTestCase())
-tdCases.addLinux(__file__, TDTestCase())
\ No newline at end of file
+tdCases.addLinux(__file__, TDTestCase())