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: http.rs
    path of file: ./repos/aws-sdk-rust/sdk/aws-smithy-checksums/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
 */

//! Checksum support for HTTP requests and responses.

use aws_smithy_types::base64;
use http::header::{HeaderMap, HeaderValue};

use crate::{
    Checksu
    
    fn test_trailer_value_of_sha1_checksum_body() {
        let checksum = SHA_1_NAME.parse::<ChecksumAlgorithm>().unwrap().into_impl();
        // The SHA1 of an empty string is da39a3ee5e6b4b0d3255bfef95601890afd80709
        let expected_value = Bytes::from_static(&[
            0xda, 0x39, 0xa3, 0xee, 0x5e, 0x6b, 0x4b, 0x0d, 0x32, 0x55, 0xbf, 0xef, 0x95, 0x60,
            0x18, 0x90, 0xaf, 0xd8, 0x07, 0x09,
        ]);
        let expected_value = base64::encode(&expected_value);
        let actual_value = checksum.header_value();
        assert_eq!(expected_value, actual_value)
    }