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: body.rs
    path of file: ./repos/roa/roa/src
    
    the code of the file until where you have to start completion: //! This module provides a context extension `PowerBody`.
//!
//! ### Read/write body in a easier way.
//!
//! The `roa_core` provides several methods to read/write body.
//!
//! ```rust
//! use roa::{Context, Result};
//! use t
    
    async fn read_json() -> Result<(), Box<dyn Error>> {
        async fn test(ctx: &mut Context) -> crate::Result {
            let user: UserDto = ctx.read_json().await?;
            assert_eq!(USER, user);
            Ok(())
        }
        let (addr, server) = App::new().end(test).run()?;
        spawn(server);

        let client = reqwest::Client::new();
        let resp = client
            .get(&format!("http://{}", addr))
            .json(&USER)
            .send()
            .await?;
        assert_eq!(StatusCode::OK, resp.status());
        Ok(())
    }