fix: ensure repeating benches return to initial run-dir (#1617)

crates/goose-bench/src/bench_work_dir.rs

@@ -11,6 +11,7 @@ pub static BUILTIN_EVAL_ASSETS: Dir = include_dir!("$CARGO_MANIFEST_DIR/src/asse
 
 pub struct BenchmarkWorkDir {
     pub base_path: PathBuf,
+    run_dir: PathBuf,
     cwd: PathBuf,
     run_name: String,
     suite: Option<String>,
@@ -24,6 +25,7 @@ impl Default for BenchmarkWorkDir {
 }
 impl BenchmarkWorkDir {
     pub fn new(work_dir_name: String, include_dirs: Vec<PathBuf>) -> Self {
+        let run_dir = std::env::current_dir().unwrap().canonicalize().unwrap();
         let base_path = PathBuf::from(format!("./benchmark-{}", work_dir_name));
         fs::create_dir_all(&base_path).unwrap();
 
@@ -54,6 +56,7 @@ impl BenchmarkWorkDir {
 
         BenchmarkWorkDir {
             base_path: base_path.clone(),
+            run_dir,
             cwd: base_path.clone(),
             run_name,
             suite: None,
@@ -178,3 +181,9 @@ impl BenchmarkWorkDir {
         }
     }
 }
+
+impl Drop for BenchmarkWorkDir {
+    fn drop(&mut self) {
+        std::env::set_current_dir(&self.run_dir).unwrap();
+    }
+}

crates/goose-bench/src/eval_suites/core/example.rs

@@ -20,15 +20,17 @@ impl Evaluation for ExampleEval {
         _work_dir: &mut BenchmarkWorkDir,
     ) -> anyhow::Result<Vec<(String, EvaluationMetric)>> {
         println!("ExampleEval - run");
-        // let f = work_dir.fs_get(String::from("./arbitrary_dir/arbitrary_file.txt"))?;
-        // let _contents = fs::read_to_string(f)?;
         let mut metrics = Vec::new();
+
         let _ = agent.prompt("What can you do?".to_string()).await;
+
         metrics.push((
             "example_metric".to_string(),
             EvaluationMetric::Boolean(true),
         ));
+
         metrics.push(("example_count".to_string(), EvaluationMetric::Integer(42)));
+
         Ok(metrics)
     }