src/lib/fuchsia-component/isolated_component_test/inner.rs

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

use {
    anyhow::Error,
    fidl_fuchsia_test_echos::{EchoExposedByParentMarker, EchoHiddenByParentMarker},
    fuchsia_async as fasync,
    fuchsia_component::client::connect_to_service,
    std::env,
    std::io::Read,
};

#[fasync::run_singlethreaded]
async fn main() -> Result<(), Error> {
    env::set_var("RUST_BACKTRACE", "full");

    // Check that only the service provided by the inner component is available,
    // and that we're connected to its implementation of the service which always
    // returns `42` rather than echoing.
    let echo = connect_to_service::<EchoExposedByParentMarker>()?;
    assert_eq!(42, echo.echo(1).await?);
    let echo = connect_to_service::<EchoHiddenByParentMarker>()?;
    match echo.echo(2).await {
        Err(e) if e.is_closed() => {}
        Ok(_) => panic!("inner nested component successfully echoed through parent"),
        Err(e) => panic!("Unexpected error connecting to hidden service: {:?}", e),
    }

    // Check that `dir_exposed_to_inner` is available.
    let mut buffer = String::new();
    std::fs::File::open("/dir_exposed_to_inner/it_works")
        .expect("open the exposed file")
        .read_to_string(&mut buffer)
        .expect("read from the exposed file");
    assert_eq!(buffer, "indeed");

    Ok(())
}