macrotest 0.1.1

Test harness for macro expansion
Documentation 
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use difference::Changeset;

/// Prints the difference of the two snippets of expanded code.
pub fn message_different(name: &str, a: &[u8], b: &[u8]) {
    let a = String::from_utf8_lossy(&a);
    let b = String::from_utf8_lossy(&b);

    let changes = Changeset::new(&a, &b, "\n");

    eprintln!("{} - different!", name);

    eprintln!();
    eprintln!("--------------------------");
    eprintln!("{}", changes.to_string());
    eprintln!("--------------------------");

}

/// Prints an error from `cargo expand` invocation.
/// Makes some suggestions when possible.
pub fn message_expansion_error(msg: Vec<u8>) {
    let msg = String::from_utf8(msg);

    eprintln!("Expansion error:");
    if let Ok(msg) = msg {
        eprintln!("{}", msg);

        // No `cargo expand` subcommand installed, make a suggestion
        if msg.contains("no such subcommand: `expand`") {
            eprintln!("Perhaps, `cargo expand` is not installed?");
            eprintln!("Install it by running:");
            eprintln!();
            eprintln!("\tcargo install cargo-expand");
            eprintln!();
        }

        // No nightly installed, make a suggestion
        if msg.starts_with("error: toolchain '") && msg.ends_with("is not installed") {
            eprintln!("You have `cargo expand` installed but it requires *nightly* compiler to be installed as well.");
            eprintln!("To install it via rustup, run:");
            eprintln!();
            eprintln!("\trustup toolchain install nightly");
            eprintln!();
        }
    } else {
        eprintln!("<unprintable>");
    }
}