diff --git a/expression/expr_to_pb_test.go b/expression/expr_to_pb_test.go
index 3c95869076a5b..30cdf5599181b 100644
--- a/expression/expr_to_pb_test.go
+++ b/expression/expr_to_pb_test.go
@@ -853,10 +853,6 @@ func TestExprPushDownToFlash(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, tipb.ScalarFuncSig_SubDateDatetimeInt, function.(*ScalarFunction).Function.PbCode())
 	exprs = append(exprs, function)
-	function, err = NewFunction(mock.NewContext(), ast.DateSub, types.NewFieldType(mysql.TypeDatetime), stringColumn, intColumn, stringColumn)
-	require.NoError(t, err)
-	require.Equal(t, tipb.ScalarFuncSig_SubDateStringInt, function.(*ScalarFunction).Function.PbCode())
-	exprs = append(exprs, function)
 	function, err = NewFunction(mock.NewContext(), ast.SubDate, types.NewFieldType(mysql.TypeDatetime), datetimeColumn, intColumn, stringColumn)
 	require.NoError(t, err)
 	require.Equal(t, tipb.ScalarFuncSig_SubDateDatetimeInt, function.(*ScalarFunction).Function.PbCode())