Fix discover::upwards when working dir is the repo

The upwards search for the repository directory takes a directory as
input and then walks through the parents. It turns out that it was
broken when the repository was the same as the working directory.

The code checked when the directory components had been stripped to "", in
case the directory was replaced with `cwd.parent()`, so the loop missed
to check `cwd` itself. If the input directory was "./something", then
"." was checked which then succeeded.

Author: moroten

gix-discover/src/upwards/mod.rs

@@ -168,11 +168,12 @@ pub(crate) mod function {
                     }
                 }
             }
-            if cursor.parent().is_some_and(|p| p.as_os_str().is_empty()) {
-                cursor = cwd.to_path_buf();
-                dir_made_absolute = true;
-            }
-            if !cursor.pop() {
+            if cursor.pop() {
+                if cursor.as_os_str().is_empty() {
+                    cursor = cwd.to_path_buf();
+                    dir_made_absolute = true;
+                }
+            } else {
                 if dir_made_absolute
                     || matches!(
                         cursor.components().next(),

gix-discover/tests/isolated.rs

@@ -3,6 +3,23 @@ use std::path::{Path, PathBuf};
 use gix_discover::upwards::Options;
 use serial_test::serial;
 
+#[test]
+#[serial]
+fn in_cwd_upwards_from_nested_dir() -> gix_testtools::Result {
+    let repo = gix_testtools::scripted_fixture_read_only("make_basic_repo.sh")?;
+
+    let _keep = gix_testtools::set_current_dir(repo)?;
+    for dir in ["subdir", "some/very/deeply/nested/subdir"] {
+        let (repo_path, _trust) = gix_discover::upwards(Path::new(dir))?;
+        assert_eq!(
+            repo_path.kind(),
+            gix_discover::repository::Kind::WorkTree { linked_git_dir: None },
+        );
+        assert_eq!(repo_path.as_ref(), Path::new("."));
+    }
+    Ok(())
+}
+
 #[test]
 #[serial]
 fn upwards_bare_repo_with_index() -> gix_testtools::Result {