path_info: check for and resolve symlink

tests/path_info.rs

@@ -1,6 +1,8 @@
 use nixcp::path_info::PathInfo;
 use std::path::PathBuf;
 
+use tempfile::TempDir;
+
 use crate::common::{HELLO, HELLO_DRV, HELLO_PATH};
 
 mod common;
@@ -25,6 +27,23 @@ async fn path_info_from_path() {
     assert_eq!(path_info.path.to_string(), HELLO_DRV);
 }
 
+#[tokio::test]
+async fn path_info_symlink() {
+    let ctx = common::context();
+
+    let temp_path = TempDir::new().unwrap();
+    let link_path = temp_path.path().join("result");
+
+    // symlink at ./result (like `nix build`)
+    std::os::unix::fs::symlink(HELLO_PATH, &link_path).unwrap();
+
+    // should resolve symlink
+    let path_info = PathInfo::from_derivation(&link_path, &ctx.store)
+        .await
+        .expect("get pathinfo from package");
+    assert_eq!(path_info.path.to_string(), HELLO_DRV);
+}
+
 #[tokio::test]
 async fn closure() {
     let ctx = common::context();