ahab/tests/support/mod.rs

// enough scaffolding to run ahab against a throwaway repository, hand-rolled
// rather than pulled in: the crate has no dependencies it does not need, and a
// dev-dependency is still something to trust and keep current.

// each integration test file compiles this module separately, so a helper only
// one of them needs looks unused to the others
#![allow(dead_code)]
use std::ffi::OsStr;
use std::fmt::Write as _;
use std::os::unix::ffi::OsStrExt;
use std::path::{Path, PathBuf};
use std::process::{Command, Output};
use std::sync::atomic::{AtomicU32, Ordering};
use std::{env, fs};

// unique per case even with the suite running in parallel
static NEXT: AtomicU32 = AtomicU32::new(0);

pub const REMOTE: &str = "https://git.example.org/acme/proj.git";

pub struct Case {
    root: PathBuf,
    // the data home every checkout of a case shares, as one user's would
    xdg: PathBuf,
    pub repo: PathBuf,
    pub store: PathBuf,
    pub outside: PathBuf,
}

impl Case {
    // a repository with an origin remote, a store of its own, and one commit
    pub fn new(label: &str) -> Self {
        let root = env::temp_dir().join(format!(
            "ahab-{label}-{}-{}",
            std::process::id(),
            NEXT.fetch_add(1, Ordering::Relaxed)
        ));
        let _ = fs::remove_dir_all(&root);

        Self::checkout(root.clone(), root.join("xdg"))
    }

    // a second clone of the same remote, sharing the first one's data home
    pub fn second_checkout(&self) -> Self {
        Self::checkout(self.root.join("second"), self.xdg.clone())
    }

    fn checkout(root: PathBuf, xdg: PathBuf) -> Self {
        let repo = root.join("repo");
        let outside = root.join("outside");
        for dir in [&repo, &outside] {
            fs::create_dir_all(dir).expect("creating the case directories");
        }

        // `<dir>-<hash>` of the canonical checkout, as ahab spells it
        let canonical = fs::canonicalize(&repo).expect("resolving the repository");
        let store = xdg.join("ahab/git.example.org/acme/proj").join(format!(
            "repo-{}",
            fingerprint(canonical.as_os_str().as_bytes())
        ));

        let case = Self {
            root,
            xdg,
            repo,
            store,
            outside,
        };

        case.git(&["init", "-q", "."]);
        case.git(&["config", "user.email", "test@example.org"]);
        case.git(&["config", "user.name", "test"]);
        case.git(&["config", "commit.gpgsign", "false"]);
        case.git(&["remote", "add", "origin", REMOTE]);
        case.write("tracked.txt", b"tracked\n");
        case.git(&["add", "tracked.txt"]);
        case.git(&["commit", "-qm", "init"]);

        case
    }

    pub fn git<S: AsRef<OsStr>>(&self, args: &[S]) -> Output {
        let out = Command::new("git")
            .current_dir(&self.repo)
            .args(args)
            .output()
            .expect("running git");

        assert!(
            out.status.success(),
            "git {:?} failed: {}",
            args.iter()
                .map(|a| a.as_ref().to_string_lossy())
                .collect::<Vec<_>>(),
            String::from_utf8_lossy(&out.stderr)
        );
        out
    }

    // ahab, in the repository, with a store nothing else shares
    pub fn ahab<S: AsRef<OsStr>>(&self, args: &[S]) -> Run {
        let out = Command::new(env!("CARGO_BIN_EXE_ahab"))
            .current_dir(&self.repo)
            .env("XDG_DATA_HOME", &self.xdg)
            // the git commands ahab runs must not read the developer's own config
            .env("GIT_CONFIG_GLOBAL", "/dev/null")
            .env("GIT_CONFIG_SYSTEM", "/dev/null")
            .args(args)
            .output()
            .expect("running ahab");

        Run {
            code: out.status.code(),
            stdout: out.stdout,
            stderr: String::from_utf8_lossy(&out.stderr).into_owned(),
        }
    }

    pub fn path(&self, rel: &str) -> PathBuf {
        self.repo.join(rel)
    }

    pub fn write(&self, rel: &str, contents: &[u8]) {
        let path = self.path(rel);
        if let Some(parent) = path.parent() {
            fs::create_dir_all(parent).expect("creating a parent directory");
        }
        fs::write(path, contents).expect("writing a file");
    }

    pub fn mkdir(&self, rel: &str) {
        fs::create_dir_all(self.path(rel)).expect("creating a directory");
    }

    pub fn link(&self, at: &Path, to: &Path) {
        if let Some(parent) = at.parent() {
            fs::create_dir_all(parent).expect("creating a parent directory");
        }
        std::os::unix::fs::symlink(to, at).expect("creating a symlink");
    }

    pub fn gitignore(&self, lines: &str) {
        self.write(".gitignore", lines.as_bytes());
        self.git(&["add", ".gitignore"]);
        self.git(&["commit", "-qm", "ignore"]);
    }

    pub fn is_symlink(&self, rel: &str) -> bool {
        fs::symlink_metadata(self.path(rel)).is_ok_and(|meta| meta.is_symlink())
    }

    pub fn mode(&self, path: &Path) -> u32 {
        use std::os::unix::fs::PermissionsExt;

        fs::symlink_metadata(path)
            .expect("reading a mode")
            .permissions()
            .mode()
            & 0o777
    }
}

impl Drop for Case {
    fn drop(&mut self) {
        let _ = fs::remove_dir_all(&self.root);
    }
}

pub struct Run {
    pub code: Option<i32>,
    pub stdout: Vec<u8>,
    pub stderr: String,
}

impl Run {
    pub fn out(&self) -> String {
        String::from_utf8_lossy(&self.stdout).into_owned()
    }

    pub fn ok(&self) -> &Self {
        assert_eq!(self.code, Some(0), "{}", self.report());
        self
    }

    pub fn failed(&self) -> &Self {
        assert_ne!(self.code, Some(0), "{}", self.report());
        self
    }

    pub fn code_is(&self, want: i32) -> &Self {
        assert_eq!(self.code, Some(want), "{}", self.report());
        self
    }

    pub fn says(&self, needle: &str) -> &Self {
        assert!(
            self.out().contains(needle) || self.stderr.contains(needle),
            "expected {needle:?}\n{}",
            self.report()
        );
        self
    }

    pub fn silent_about(&self, needle: &str) -> &Self {
        assert!(
            !self.out().contains(needle) && !self.stderr.contains(needle),
            "did not expect {needle:?}\n{}",
            self.report()
        );
        self
    }

    fn report(&self) -> String {
        let mut out = String::new();
        let _ = write!(
            out,
            "exit: {:?}\n--- stdout\n{}--- stderr\n{}",
            self.code,
            self.out(),
            self.stderr
        );
        out
    }
}

// fnv-1a, as the store spells a checkout
pub fn fingerprint(bytes: &[u8]) -> String {
    let mut hash: u64 = 0xcbf2_9ce4_8422_2325;

    for byte in bytes {
        hash ^= u64::from(*byte);
        hash = hash.wrapping_mul(0x100_0000_01b3);
    }

    format!("{:08x}", hash as u32)
}