Add test for clrs

tests/integration/test_keeper_four_word_command/test.py

@@ -679,3 +679,41 @@ def test_cmd_rqld(started_cluster):
                     + " does not become leader after 30s, maybe there is something wrong."
                 )
         assert keeper_utils.is_leader(cluster, node)
+
+
+def test_cmd_clrs(started_cluster):
+    def get_memory_purges():
+        return node1.query(
+            "SELECT value FROM system.events WHERE event = 'MemoryAllocatorPurge' SETTINGS system_events_show_zero_values = 1"
+        )
+
+    zk = None
+    try:
+        wait_nodes()
+
+        zk = get_fake_zk(node1.name, timeout=30.0)
+
+        paths = [f"/clrs_{i}" for i in range(10000)]
+
+        # we only count the events because we cannot reliably test memory usage of Keeper
+        # but let's create and delete nodes so the first purge needs to release some memory
+        create_transaction = zk.transaction()
+        for path in paths:
+            create_transaction.create(path)
+        create_transaction.commit()
+
+        delete_transaction = zk.transaction()
+        for path in paths:
+            delete_transaction.delete(path)
+        delete_transaction.commit()
+
+        # repeat multiple times to make sure MemoryAllocatorPurge isn't increased because of other reasons
+        for _ in range(5):
+            prev_purges = int(get_memory_purges())
+            keeper_utils.send_4lw_cmd(cluster, node1, cmd="clrs")
+            current_purges = int(get_memory_purges())
+            assert current_purges > prev_purges
+            prev_purges = current_purges
+
+    finally:
+        destroy_zk_client(zk)