Improve the Debug implementation of Command

[nwalfield]

In my project, I build up a command to run dynamically. For instance, I have a test where I check that it is possible to specify the input on the command line or via stdin. It looks something like this:

for stdin in [false, true] {
        let mut cmd = Command::cargo_bin("sq")?;
        cmd.args(&["revoke",
                   "certificate",
                   "compromised", "oh no!"]);

        if let Some(dir) = tmp_dir.as_ref() {
            let alice_pgp = dir.path().join("alice.pgp");
            let mut file = File::create(&alice_pgp)?;
            file.write_all(&alice_tsk)?;

            cmd.args(&["--certificate", &*alice_pgp.to_string_lossy()]);
        } else {
            cmd.write_stdin(alice_tsk);
        }
}

I wanted to print out what is going to be run, so I added: eprintln!("Running: {:?}", cmd);. That prints:

Running: Command { cmd: "/tmp/sequoia-build/debug/sq" "revoke" "certificate" "compromised" "xyzzy" "--certificate" "/tmp/.tmpSZuU4h/alice.pgp", stdin: None, timeout: None }
Running: Command { cmd: "/tmp/sequoia-build/debug/sq" "revoke" "certificate" "compromised" "xyzzy", stdin: Some([197, 88, 4, 97, 224, 39, 221, 22, 9, 43, 6, 1, 4, 1, 218, 71, 15, 1, 1, 7, 64, 10, 134, ... pages and pages of numbers ...

In the case where I feed the data via stdin, that is very noisy. (I would have been happy to just print the command, but cmd is private and I didn't find a getter. Perhaps it makes sense to add one.) I think it would be better to do something like the following:

• If stdin is, say, only printable ascii characters print it as such
• Otherwise, print it as nicely formatted hex similar to xxd:

$ echo foobar | xxd 
00000000: 666f 6f62 6172 0a                        foobar.

Thanks for the great project!

[nwalfield]

Thanks a lot for the quick response!

I just tried it, and it works much better. It's not great for binary data:

 stdin: Some("\xC5X\x04a\xE0p\x97\x16\t+\x06\x01\x04\x01\xDAG\x0f\x01\x01\x07@\xD1\xDBH\xB...

but it's a definite improvement!