Clarify dbm.dumb bytearray handling and cover with test

Author: furkanonder

Doc/library/dbm.rst

@@ -130,7 +130,10 @@ Key and Value Types
 The accepted types for keys and values vary by backend. Keys and values are
 handled identically:
 
-* **Traditional backends**: :mod:`dbm.gnu`, :mod:`dbm.ndbm`, and :mod:`dbm.dumb` accept :class:`str` and :class:`bytes` objects.
+* **Traditional backends**:
+
+  * :mod:`dbm.gnu` and :mod:`dbm.ndbm`: Accept :class:`str` and :class:`bytes` objects.
+  * :mod:`dbm.dumb`: Accepts :class:`str` and :class:`bytes` objects; :class:`bytearray` is acceptable as a value, but not as a key.
 * **SQLite backend** (:mod:`dbm.sqlite3`): Accepts :class:`str`, :class:`bytes`,
   :class:`int`, :class:`float`, :class:`bool`, :class:`bytearray`,
   :class:`memoryview`, and :class:`array.array` objects.
@@ -151,8 +154,6 @@ type stored.
 * ``db['key'] = False`` stored as ``b'0'`` (:mod:`dbm.sqlite3` only)
 * ``db['key'] = memoryview(b'data')`` stored as ``b'data'`` (:mod:`dbm.sqlite3` only)
 * ``db['key'] = array.array('i', [1, 2, 3])`` stored as bytes (e.g. on little-endian: ``b'\x01\x00\x00\x00\x02\x00\x00\x00\x03\x00\x00\x00'``) (:mod:`dbm.sqlite3` only)
-* ``db['key'] = None`` fails on all backends
-* ``db['key'] = [1, 2, 3]`` fails on all backends
 
 
 The following example records some hostnames and a corresponding title,  and

Lib/test/test_dbm_dumb.py

@@ -31,6 +31,7 @@ class DumbDBMTestCase(unittest.TestCase):
              b'd': b'way',
              b'f': b'Guido',
              b'g': b'intended',
+             b'h': bytearray(b'bytearray_value'),
              '\u00fc'.encode('utf-8') : b'!',
              }
 
@@ -368,6 +369,14 @@ def test_nonascii_filename(self):
             self.assertTrue(b'key' in db)
             self.assertEqual(db[b'key'], b'value')
 
+    def test_bytearray(self):
+        self.init_db()
+        with contextlib.closing(dumbdbm.open(_fname, 'r')) as f:
+            self.assertEqual(f[b'h'], b'bytearray_value')
+        with contextlib.closing(dumbdbm.open(_fname)) as f:
+            with self.assertRaises(TypeError):
+                f[bytearray(b'bytearray_key')] = b'value'
+
     def test_open_with_pathlib_path(self):
         dumbdbm.open(os_helper.FakePath(_fname), "c").close()