Fix regression in package.yml metadata.owner key

As far as I can tell, this key was not intentionally removed and
its presence is missed. Based on issues reported, We're restoring
support rather than fix all the other things that depend on it.

Related to: rubyatscale/code_ownership#141

Author: martinemde

src/project.rs

@@ -111,6 +111,7 @@ pub mod deserializers {
     #[derive(Deserialize)]
     pub struct RubyPackage {
         pub owner: Option<String>,
+        pub metadata: Option<Metadata>,
     }
 
     #[derive(Deserialize)]

src/project_builder.rs

@@ -309,7 +309,17 @@ fn ruby_package_owner(path: &Path) -> Result<Option<String>, Error> {
     let file = File::open(path).change_context(Error::Io)?;
     let deserializer: deserializers::RubyPackage = serde_yaml::from_reader(file).change_context(Error::SerdeYaml)?;
 
-    Ok(deserializer.owner)
+    let top_level_owner = deserializer.owner;
+    let metadata_owner = deserializer.metadata.and_then(|metadata| metadata.owner);
+
+    // Error if both are present to avoid ambiguity
+    match (top_level_owner.as_ref(), metadata_owner.as_ref()) {
+        (Some(_), Some(_)) => Err(error_stack::report!(Error::Io).attach_printable(format!(
+            "Package at {} has both 'owner' and 'metadata.owner' defined. Please use only one.",
+            path.display()
+        ))),
+        _ => Ok(top_level_owner.or(metadata_owner)),
+    }
 }
 
 fn javascript_package_owner(path: &Path) -> Result<Option<String>, Error> {
@@ -334,4 +344,44 @@ mod tests {
     fn test_glob_match() {
         assert!(glob_match(OWNED_GLOB, "script/.eslintrc.js"));
     }
+
+    #[test]
+    fn test_ruby_package_owner_top_level() {
+        let yaml = "owner: TeamA\n";
+        let temp_file = tempfile::NamedTempFile::new().unwrap();
+        std::fs::write(temp_file.path(), yaml).unwrap();
+
+        let owner = ruby_package_owner(temp_file.path()).unwrap();
+        assert_eq!(owner, Some("TeamA".to_string()));
+    }
+
+    #[test]
+    fn test_ruby_package_owner_metadata() {
+        let yaml = "metadata:\n  owner: TeamB\n";
+        let temp_file = tempfile::NamedTempFile::new().unwrap();
+        std::fs::write(temp_file.path(), yaml).unwrap();
+
+        let owner = ruby_package_owner(temp_file.path()).unwrap();
+        assert_eq!(owner, Some("TeamB".to_string()));
+    }
+
+    #[test]
+    fn test_ruby_package_owner_errors_when_both_present() {
+        let yaml = "owner: TeamA\nmetadata:\n  owner: TeamB\n";
+        let temp_file = tempfile::NamedTempFile::new().unwrap();
+        std::fs::write(temp_file.path(), yaml).unwrap();
+
+        let result = ruby_package_owner(temp_file.path());
+        assert!(result.is_err());
+    }
+
+    #[test]
+    fn test_ruby_package_owner_no_owner() {
+        let yaml = "name: my_package\n";
+        let temp_file = tempfile::NamedTempFile::new().unwrap();
+        std::fs::write(temp_file.path(), yaml).unwrap();
+
+        let owner = ruby_package_owner(temp_file.path()).unwrap();
+        assert_eq!(owner, None);
+    }
 }