Chapter 07: Race condition in the tests

[jclin]

Hi,

Chapter 07's tests will intermittently fail because of how cargo test runs tests concurrently by default. Specifically, when unreadable_dir creates tests/inputs/cant-touch-this, other tests will unintentionally detect that dir and include it in its output.

As a workaround, the run function was modified to filter that directory out:

fn run(args: &[&str], expected_file: &str) -> Result<()> {
    let file = format_file_name(expected_file);
    let contents = fs::read_to_string(file.as_ref())?;
    let mut expected: Vec<&str> =
        contents.split('\n').filter(|s| !s.is_empty()).collect();
    expected.sort();

    let cmd = Command::cargo_bin(PRG)?.args(args).assert().success();
    let out = cmd.get_output();
    let stdout = String::from_utf8(out.stdout.clone())?;
    // unreadable_dir creates tests/inputs/cant-touch-this while tests run in
    // parallel; ignore it so tests scanning tests/inputs don't race with it.
    let mut lines: Vec<&str> = stdout
        .split('\n')
        .filter(|s| !s.is_empty() && !s.contains("cant-touch-this"))
        .collect();
    lines.sort();

    assert_eq!(lines, expected);

    Ok(())
}