add test

tests/queries/0_stateless/02813_system_events_and_metrics_add_alias.reference

@@ -0,0 +1,4 @@
+CREATE TABLE system.metrics\n(\n `metric` String,\n `value` Int64,\n `description` String,\n `name` String\n)\nENGINE = SystemMetrics\nCOMMENT \'SYSTEM TABLE is built on the fly.\'
+1
+CREATE TABLE system.events\n(\n `event` String,\n `value` UInt64,\n `description` String,\n `name` String\n)\nENGINE = SystemEvents\nCOMMENT \'SYSTEM TABLE is built on the fly.\'
+1

tests/queries/0_stateless/02813_system_events_and_metrics_add_alias.sql

@@ -0,0 +1,4 @@
+show create table system.metrics;
+select equals((select count() from system.metrics where name=metric) as r1, (select count() from system.metrics) as r2);
+show create table system.events;
+select equals((select count() from system.events where name=event) as r1, (select count() from system.events) as r2);