eval_magic/core/
runtime.rs

1//! Runtime helpers.
2//!
3//! The synchronous git invocation helper. No runtime asset locator lives here:
4//! the schemas are bundled into the binary at compile time (`include_str!`),
5//! `clap` owns argument parsing, and the `error: <msg>` + exit(1) contract
6//! lives in `src/main.rs`.
7
8use std::path::Path;
9use std::process::Command;
10
11/// Outcome of a git invocation.
12///
13/// `status` is `None` when git could not be spawned at all (e.g. ENOENT, a
14/// nonexistent cwd, permission denied); the reason is surfaced into `stderr`,
15/// so callers have one channel for both git's own errors and spawn failures.
16/// `stdout` and
17/// `stderr` are raw bytes — callers that read file contents out of git
18/// (`git show`) need the undecoded buffer, not a lossy UTF-8 string.
19#[derive(Debug)]
20pub struct GitOutput {
21    pub status: Option<i32>,
22    pub stdout: Vec<u8>,
23    pub stderr: Vec<u8>,
24}
25
26/// Synchronously invoke `git` with `args` in `cwd`, returning its status and raw
27/// output. A failure to spawn git is not an error here: it yields `status: None`
28/// with the spawn error surfaced into `stderr`, so callers can handle it
29/// alongside git's own failures.
30pub fn run_git(args: &[&str], cwd: &Path) -> GitOutput {
31    match Command::new("git").args(args).current_dir(cwd).output() {
32        Ok(out) => GitOutput {
33            status: out.status.code(),
34            stdout: out.stdout,
35            stderr: out.stderr,
36        },
37        Err(err) => GitOutput {
38            status: None,
39            stdout: Vec::new(),
40            stderr: format!("{err}").into_bytes(),
41        },
42    }
43}
44
45#[cfg(test)]
46mod tests {
47    use super::*;
48
49    /// A successful git command returns exit status 0 and writes to stdout.
50    /// Run against this crate's own repo, which has commit history.
51    #[test]
52    fn run_git_success_status_and_stdout() {
53        let res = run_git(
54            &["rev-parse", "--short", "HEAD"],
55            env!("CARGO_MANIFEST_DIR").as_ref(),
56        );
57        assert_eq!(res.status, Some(0));
58        assert!(String::from_utf8_lossy(&res.stdout).trim().len() > 3);
59    }
60
61    /// A git command that fails (bad ref) returns a non-zero status.
62    #[test]
63    fn run_git_failing_command_nonzero() {
64        let res = run_git(
65            &["rev-parse", "not-a-real-ref-xyz"],
66            env!("CARGO_MANIFEST_DIR").as_ref(),
67        );
68        assert_ne!(res.status, Some(0));
69    }
70
71    /// When git itself cannot be spawned (here, a nonexistent cwd), the status
72    /// is `None` and the spawn error is surfaced into stderr — the contract is
73    /// the null status plus a readable reason, not any particular error-code
74    /// spelling.
75    #[test]
76    fn run_git_spawn_error_surfaced() {
77        let res = run_git(
78            &["rev-parse", "HEAD"],
79            "/nonexistent-dir-for-rungit-test".as_ref(),
80        );
81        assert_eq!(res.status, None);
82        assert!(String::from_utf8_lossy(&res.stderr).contains("No such file or directory"));
83    }
84}
eval_magic/core/runtime.rs

eval_magic/core/
runtime.rs
