clippy: tests: Fix clippy warnings. (#710)

tests/criterion_tests.rs

@@ -52,7 +52,7 @@ impl Default for Counter {
     }
 }
 
-fn verify_file(dir: &PathBuf, path: &str) -> PathBuf {
+fn verify_file(dir: &Path, path: &str) -> PathBuf {
     let full_path = dir.join(path);
     assert!(
         full_path.is_file(),
@@ -64,36 +64,36 @@ fn verify_file(dir: &PathBuf, path: &str) -> PathBuf {
     full_path
 }
 
-fn verify_json(dir: &PathBuf, path: &str) {
+fn verify_json(dir: &Path, path: &str) {
     let full_path = verify_file(dir, path);
     let f = File::open(full_path).unwrap();
     serde_json::from_reader::<File, Value>(f).unwrap();
 }
 
 #[cfg(feature = "html_reports")]
-fn verify_svg(dir: &PathBuf, path: &str) {
+fn verify_svg(dir: &Path, path: &str) {
     verify_file(dir, path);
 }
 
 #[cfg(feature = "html_reports")]
-fn verify_html(dir: &PathBuf, path: &str) {
+fn verify_html(dir: &Path, path: &str) {
     verify_file(dir, path);
 }
 
-fn verify_stats(dir: &PathBuf, baseline: &str) {
+fn verify_stats(dir: &Path, baseline: &str) {
     verify_json(dir, &format!("{}/estimates.json", baseline));
     verify_json(dir, &format!("{}/sample.json", baseline));
     verify_json(dir, &format!("{}/tukey.json", baseline));
     verify_json(dir, &format!("{}/benchmark.json", baseline));
     #[cfg(feature = "csv_output")]
-    verify_file(&dir, &format!("{}/raw.csv", baseline));
+    verify_file(dir, &format!("{}/raw.csv", baseline));
 }
 
-fn verify_not_exists(dir: &PathBuf, path: &str) {
+fn verify_not_exists(dir: &Path, path: &str) {
     assert!(!dir.join(path).exists());
 }
 
-fn latest_modified(dir: &PathBuf) -> SystemTime {
+fn latest_modified(dir: &Path) -> SystemTime {
     let mut newest_update: Option<SystemTime> = None;
     for entry in WalkDir::new(dir) {
         let entry = entry.unwrap();