You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: websocket.rs
    path of file: ./repos/exonum/services/explorer/tests
    
    the code of the file until where you have to start completion: // Copyright 2020 The Exonum Team
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIO
    
async fn test_blocks_subscription() {
    let (mut testkit, api) = init_testkit();
    let url = api.public_url("api/explorer/v1/blocks/subscribe");
    let mut client = create_ws_client(&url).await;

    testkit.create_block();
    // Get the block notification.
    let notification: Notification = receive_message(&mut client).await.unwrap();
    assert_matches!(notification, Notification::Block(ref block) if block.height == Height(1));

    // Create one more block.
    testkit.create_block();
    let notification: Notification = receive_message(&mut client).await.unwrap();
    assert_matches!(notification, Notification::Block(ref block) if block.height == Height(2));
}