The Command's stdin and simulating piped input

The behaviour of Stdin of the Command can be changed, almost the same way as the Stdin of a std::process::Command with the only difference, that we use the enums gungraun::Stdin and gungraun::Stdio. These enums provide the variants Inherit (the equivalent of std::process::Stdio::inherit), Pipe (the equivalent of std::process::Stdio::piped) and so on. There's also File which takes a PathBuf to the file which is used as Stdin for the Command. This corresponds to a redirection in the shell as in my-foo < path/to/file.

Moreover, gungraun::Stdin provides the Stdin::Setup variant specific to Gungraun:

Applications may change their behaviour if the input or the Stdin of the Command is coming from a pipe as in echo "some content" | my-foo. To be able to benchmark such cases, it is possible to use the output of setup to Stdout or Stderr as Stdin for the Command.

extern crate gungraun;
macro_rules! env { ($m:tt) => {{ "/some/path" }} }
use gungraun::{binary_benchmark, binary_benchmark_group, main, Stdin, Pipe};

fn setup_pipe() {
    println!(
        "The output to `Stdout` here will be the input or `Stdin` of the `Command`"
    );
}

#[binary_benchmark]
#[bench::foo(setup = setup_pipe())]
fn bench_binary() -> gungraun::Command {
    gungraun::Command::new(env!("CARGO_BIN_EXE_my-foo"))
        .stdin(Stdin::Setup(Pipe::Stdout))
        .build()
}

binary_benchmark_group!(name = my_group; benchmarks = bench_binary);
fn main() {
main!(binary_benchmark_groups = my_group);
}

Usually, setup then the Command and then teardown are executed sequentially, each waiting for the previous process to exit successfully (See also Configure the exit code of the Command). If the Command::stdin changes to Stdin::Setup, setup and the Command are executed in parallel and Gungraun waits first for the Command to exit, then setup. After the successful exit of setup, teardown is executed.

Since setup and Command are run in parallel if Stdin::Setup is used, it is sometimes necessary to delay the execution of the Command. Please see the delay chapter for more details.