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: replay.rs
    path of file: ./repos/aws-sdk-rust/examples/examples/testing/src
    
    the code of the file until where you have to start completion: // Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

// snippet-start:[testing.rust.replay-uses]
use aws_sdk_s3 as s3;
// snippet-end:[testing.rust.replay-uses]

#[allow(dead_code)]
// snippet-start:[testing.rust.replay]
pub async fn determine_prefix_file_size(
    // Now we take a reference to our trait object instead of the S3 client
    // s3_list: ListObjectsService,
    s3: s3::Client,
    bucket: &str,
    prefix: &str,
) -> Result<usize, s3::Error> {
    let mut next_token: Option<String> = None;
    let mut total_size_bytes = 0;
    loop {
        let result = s3
            .list_objects_v2()
            .prefix(prefix)
            .bucket(bucket)
            .set_continuation_token(next_token.take())
            .send()
            .await?;

        // Add up the file sizes we got back
        for object in result.contents() {
            total_size_bytes += object.size().unwrap_or(0) as usize;
        }

        // Handle pagination, and break the loop if there are no more pages
        next_token = result.next_continuation_token.clone();
        if next_token.is_none() {
            break;
        }
    }
    Ok(total_size_bytes)
}
// snippet-end:[testing.rust.replay]

#[allow(dead_code)]
// snippet-start:[testing.rust.replay-tests]
// snippet-start:[testing.rust.replay-make-credentials]
fn make_s3_test_credentials() -> s3::config::Credentials {
    s3::config::Credentials::new(
        "ATESTCLIENT",
        "astestsecretkey",
        Some("atestsessiontoken".to_string()),
        None,
        "",
    )
}
// snippet-end:[testing.rust.replay-make-credentials]

// snippet-start:[testing.rust.replay-test-module]
#[cfg(test)]
mod test {
    // snippet-start:[testing.rust.replay-test-single]
    use super::*;
  
    
    async fn test_multiple_pages() {
        // snippet-start:[testing.rust.replay-create-replay]
        let page_1 = ReplayEvent::new(
                http::Request::builder()
                    .method("GET")
                    .uri("https://test-bucket.s3.us-east-1.amazonaws.com/?list-type=2&prefix=test-prefix")
                    .body(SdkBody::empty())
                    .unwrap(),
                http::Response::builder()
                    .status(200)
                    .body(SdkBody::from(include_str!("./testing/response_multi_1.xml")))
                    .unwrap(),
            );
        let page_2 = ReplayEvent::new(
                http::Request::builder()
                    .method("GET")
                    .uri("https://test-bucket.s3.us-east-1.amazonaws.com/?list-type=2&prefix=test-prefix&continuation-token=next")
                    .body(SdkBody::empty())
                    .unwrap(),
                http::Response::builder()
                    .status(200)
                    .body(SdkBody::from(include_str!("./testing/response_multi_2.xml")))
                    .unwrap(),
            );
        let replay_client = StaticReplayClient::new(vec![page_1, page_2]);
        // snippet-end:[testing.rust.replay-create-replay]
        // snippet-start:[testing.rust.replay-create-client]
        let client: s3::Client = s3::Client::from_conf(
            s3::Config::builder()
                .behavior_version(BehaviorVersion::latest())
                .credentials_provider(make_s3_test_credentials())
                .region(s3::config::Region::new("us-east-1"))
                .http_client(replay_client.clone())
                .build(),
        );
        // snippet-end:[testing.rust.replay-create-client]

        // Run the code we want to test with it
        // snippet-start:[testing.rust.replay-test-and-verify]
        let size = determine_prefix_file_size(client, "test-bucket", "test-prefix")
            .await
            .unwrap();

        assert_eq!(19, size);

        replay_client.assert_requests_match(&[]);
        // snippet-end:[testing.rust.replay-test-and-verify]
    }