new: scaffold new Debian source packages (non-interactive core)

src/new/git.rs

@@ -0,0 +1,64 @@
+//! Git handling for `pkh new`: initialize a repository in the scaffolded
+//! tree unless it is already inside one (the `.gitignore`s are written
+//! regardless).
+
+use std::path::Path;
+
+/// Ensure `dir` has a git repository when it should: when `dir` is already
+/// inside a work tree (its own or a parent's), nothing is initialized and
+/// `Ok(false)` is returned with an info log; otherwise a repository is
+/// initialized in `dir` when `init` is set (the `--no-git` case passes
+/// `init = false`).
+pub fn ensure_repository(dir: &Path, init: bool) -> Result<bool, Box<dyn std::error::Error>> {
+    match git2::Repository::discover(dir) {
+        Ok(_) => {
+            log::info!(
+                "Already inside a git repository; skipping git init \
+                 (the .gitignore files are written anyway)"
+            );
+            Ok(false)
+        }
+        Err(_) if init => {
+            git2::Repository::init(dir)?;
+            log::info!("Initialized empty git repository in {}", dir.display());
+            Ok(true)
+        }
+        // --no-git: gitignores only.
+        Err(_) => Ok(false),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tempfile::tempdir;
+
+    #[test]
+    fn init_skipped_with_no_git() {
+        let dir = tempdir().unwrap();
+        assert!(!ensure_repository(dir.path(), false).unwrap());
+        assert!(!dir.path().join(".git").exists());
+    }
+
+    #[test]
+    fn init_creates_repository() {
+        let dir = tempdir().unwrap();
+        assert!(ensure_repository(dir.path(), true).unwrap());
+        assert!(dir.path().join(".git").exists());
+
+        // A second call discovers the fresh repository and skips init.
+        assert!(!ensure_repository(dir.path(), true).unwrap());
+    }
+
+    #[test]
+    fn parent_repository_is_discovered() {
+        let dir = tempdir().unwrap();
+        let sub = dir.path().join("sub");
+        std::fs::create_dir_all(&sub).unwrap();
+        git2::Repository::init(dir.path()).unwrap();
+
+        // The subdirectory is already inside the parent work tree.
+        assert!(!ensure_repository(&sub, true).unwrap());
+        assert!(!sub.join(".git").exists());
+    }
+}