Add pathlib.Path support to `cmuarctic` (#1025)

test/torchaudio_unittest/datasets/cmuarctic_test.py

 import os
+from pathlib import Path
 
 from torchaudio.datasets import cmuarctic
 
@@ -54,8 +55,7 @@ class TestCMUARCTIC(TempDirMixin, TorchaudioTestCase):
                     txt.write(f'( {utterance_id} "{utterance}" )\n')
                     seed += 1
 
-    def test_cmuarctic(self):
-        dataset = cmuarctic.CMUARCTIC(self.root_dir)
+    def _test_cmuarctic(self, dataset):
         n_ite = 0
         for i, (waveform, sample_rate, utterance, utterance_id) in enumerate(dataset):
             expected_sample = self.samples[i]
@@ -65,3 +65,11 @@ class TestCMUARCTIC(TempDirMixin, TorchaudioTestCase):
             self.assertEqual(expected_sample[0], waveform, atol=5e-5, rtol=1e-8)
             n_ite += 1
         assert n_ite == len(self.samples)
+
+    def test_cmuarctic_str(self):
+        dataset = cmuarctic.CMUARCTIC(self.root_dir)
+        self._test_cmuarctic(dataset)
+
+    def test_cmuarctic_path(self):
+        dataset = cmuarctic.CMUARCTIC(Path(self.root_dir))
+        self._test_cmuarctic(dataset)

torchaudio/datasets/cmuarctic.py

 import os
-from typing import Tuple
+from pathlib import Path
+from typing import Tuple, Union
 
 import torchaudio
 from torch import Tensor
@@ -79,7 +80,7 @@ class CMUARCTIC(Dataset):
     """Create a Dataset for CMU_ARCTIC.
 
     Args:
-        root (str): Path to the directory where the dataset is found or downloaded.
+        root (str or Path): Path to the directory where the dataset is found or downloaded.
         url (str, optional):
             The URL to download the dataset from or the type of the dataset to dowload.
             (default: ``"aew"``)
@@ -98,7 +99,7 @@ class CMUARCTIC(Dataset):
     _folder_audio = "wav"
 
     def __init__(self,
-                 root: str,
+                 root: Union[str, Path],
                  url: str = URL,
                  folder_in_archive: str = FOLDER_IN_ARCHIVE,
                  download: bool = False) -> None:
@@ -130,6 +131,9 @@ class CMUARCTIC(Dataset):
 
             url = os.path.join(base_url, url + ext_archive)
 
+        # Get string representation of 'root' in case Path object is passed
+        root = os.fspath(root)
+
         basename = os.path.basename(url)
         root = os.path.join(root, folder_in_archive)
         if not os.path.isdir(root):