test(infra): test the path resoltion error variants (#2210)

* test(infra): test the path resoltion error variants

* test(infra): simplify resolve project relative path tests

crates/infra_utils/src/path.rs

@@ -4,11 +4,17 @@ use std::sync::LazyLock;
 
 use thiserror::Error;
 
+#[cfg(test)]
+#[path = "path_test.rs"]
+mod path_test;
+
 #[derive(Debug, Error)]
 pub enum PathResolutionError {
     // TODO(Arni): Handle manifest dir not exist here?
     #[error("No file exists at '{path}'")]
     PathDoesNotExist { path: PathBuf },
+    /// This error is raised when file existence can be neither confirmed nor denied. See
+    /// [`std::path::Path::try_exists`] for more information.
     #[error(transparent)]
     IoError(#[from] std::io::Error),
 }

crates/infra_utils/src/path_test.rs

@@ -0,0 +1,24 @@
+use crate::path::{path_of_project_root, resolve_project_relative_path, PathResolutionError};
+
+// TODO: Add a test for PathResolutionError::IoError.
+#[test]
+fn resolve_project_relative_path_on_non_existent_path() {
+    let relative_path = "does_not_exist.txt";
+    let expected_path = path_of_project_root().join(relative_path);
+    assert!(!expected_path.exists());
+    let result = resolve_project_relative_path(relative_path);
+
+    if let Err(PathResolutionError::PathDoesNotExist { path }) = result {
+        assert_eq!(path, expected_path);
+    } else {
+        panic!("Expected PathDoesNotExist error, got {:?}", result);
+    }
+}
+
+#[test]
+fn resolve_project_relative_path_success() {
+    let relative_path = std::file!();
+    let result = resolve_project_relative_path(relative_path);
+
+    assert!(result.unwrap().ends_with(relative_path));
+}