reqwest crate GET方法报错RelativeUrlWithoutBase的解决办法

问题背景 #

跟随《Zero to Production》书籍学习时，此前正常运行的健康检查测试，执行cargo test时抛出RelativeUrlWithoutBase错误。

相关代码 #

TestApp 定义与 spawn_app 函数 #

pub struct TestApp {
    pub address: String,
    pub pool: PgPool,
}

async fn spawn_app() -> TestApp {
    let listener = TcpListener::bind("127.0.0.1:0").expect("failed to bind to the port");
    let port = listener.local_addr().unwrap().port();
    let address = format!("127.0.0.1:{}", port);

    let configuration = get_configuration().expect("failed to read configuration");
    let connection_pool = PgPool::connect(&configuration.database.connection_string()).await.expect("failed to connect to postgres");
    let server = run(listener, connection_pool.clone()).expect("failed to bind to address");
    let _ = tokio::spawn(server);
    TestApp{
        address,
        pool: connection_pool,
    }
}

测试函数 #

#[tokio::test]
async fn health_check_works() {
    let app = spawn_app().await;
    let client = reqwest::Client::new();
    let response = client
        .get(&format!("{}/health_check",&app.address))
        .send()
        .await
        .expect("Failed to execute request.");
    assert!(response.status().is_success());
    assert_eq!(Some(0), response.content_length());
}

错误信息 #

thread 'health_check_works' panicked at 'Failed to execute request.: reqwest::Error { kind: Builder, source: RelativeUrlWithoutBase }', tests/health_check.rs:36:10

原因 #

reqwest 的 get 方法要求传入完整的绝对URL（必须包含协议前缀，如http://）。当前代码生成的address仅为127.0.0.1:xxxx格式，缺少协议前缀，导致reqwest无法识别为合法的基础URL，进而判定为相对路径，抛出该错误。

解决步骤 #

修改spawn_app函数中生成address的代码，添加http://前缀：

// 原代码
// let address = format!("127.0.0.1:{}", port);
// 修改后
let address = format!("http://127.0.0.1:{}", port);

修改后，测试函数拼接出的URL为http://127.0.0.1:xxxx/health_check，属于完整的绝对URL，reqwest可正常解析并发送请求。

内容的提问来源于stack exchange，提问作者Sarang Dutta