uutests: Change dir_exists to take a templated AsRef<Path>

Similar to what file_exists does, allows us to pass an OsStr to the
function.

Also change symlink_exists, for consistency.

tests/by-util/test_cp.rs

@@ -5837,7 +5837,7 @@ fn test_dir_perm_race_with_preserve_mode_and_ownership() {
                 start_time.elapsed() < timeout,
                 "timed out: cp took too long to create destination directory"
             );
-            if at.dir_exists(&format!("{DEST_DIR}/{SRC_DIR}")) {
+            if at.dir_exists(format!("{DEST_DIR}/{SRC_DIR}")) {
                 break;
             }
             sleep(Duration::from_millis(100));

tests/by-util/test_mv.rs

@@ -228,8 +228,8 @@ fn test_mv_multiple_folders() {
         .succeeds()
         .no_stderr();
 
-    assert!(at.dir_exists(&format!("{target_dir}/{dir_a}")));
-    assert!(at.dir_exists(&format!("{target_dir}/{dir_b}")));
+    assert!(at.dir_exists(format!("{target_dir}/{dir_a}")));
+    assert!(at.dir_exists(format!("{target_dir}/{dir_b}")));
 }
 
 #[test]
@@ -555,7 +555,7 @@ fn test_mv_hardlink_to_symlink() {
         .arg(hardlink_to_symlink_file)
         .succeeds();
     assert!(!at2.symlink_exists(symlink_file));
-    assert!(at2.symlink_exists(&format!("{hardlink_to_symlink_file}~")));
+    assert!(at2.symlink_exists(format!("{hardlink_to_symlink_file}~")));
 }
 
 #[test]
@@ -649,7 +649,7 @@ fn test_mv_simple_backup_for_directory() {
 
     assert!(!at.dir_exists(dir_a));
     assert!(at.dir_exists(dir_b));
-    assert!(at.dir_exists(&format!("{dir_b}~")));
+    assert!(at.dir_exists(format!("{dir_b}~")));
     assert!(at.file_exists(format!("{dir_b}/file_a")));
     assert!(at.file_exists(format!("{dir_b}~/file_b")));
 }
@@ -1353,7 +1353,7 @@ fn test_mv_backup_dir() {
 
     assert!(!at.dir_exists(dir_a));
     assert!(at.dir_exists(dir_b));
-    assert!(at.dir_exists(&format!("{dir_b}~")));
+    assert!(at.dir_exists(format!("{dir_b}~")));
 }
 
 #[test]
@@ -1572,7 +1572,7 @@ fn test_mv_dir_into_dir_with_source_name_a_prefix_of_target_name() {
 
     ucmd.arg(source).arg(target).succeeds().no_output();
 
-    assert!(at.dir_exists(&format!("{target}/{source}")));
+    assert!(at.dir_exists(format!("{target}/{source}")));
 }
 
 #[test]

tests/uutests/src/lib/util.rs

@@ -1243,14 +1243,14 @@ impl AtPath {
     }
 
     /// Decide whether the named symbolic link exists in the test directory.
-    pub fn symlink_exists(&self, path: &str) -> bool {
+    pub fn symlink_exists<P: AsRef<Path>>(&self, path: P) -> bool {
         match fs::symlink_metadata(self.plus(path)) {
             Ok(m) => m.file_type().is_symlink(),
             Err(_) => false,
         }
     }
 
-    pub fn dir_exists(&self, path: &str) -> bool {
+    pub fn dir_exists<P: AsRef<Path>>(&self, path: P) -> bool {
         match fs::metadata(self.plus(path)) {
             Ok(m) => m.is_dir(),
             Err(_) => false,