diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3eb975a..0d60d2a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,7 +7,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
-// Add your changes here and then delete this line
+### Added
+
+* Added `MemoryCacheHandler`, a cache handler that simply stores the token info in memory as an instance attribute of this class.
+
+### Fixed
+
+* Fixed a bug in `CacheFileHandler.__init__`: The documentation says that the username will be retrieved from the environment, but it wasn't.
 
 ## [2.18.0] - 2021-04-13
 
diff --git a/spotipy/cache_handler.py b/spotipy/cache_handler.py
index 3ba3987..544316b 100644
--- a/spotipy/cache_handler.py
+++ b/spotipy/cache_handler.py
@@ -1,8 +1,10 @@
-__all__ = ['CacheHandler', 'CacheFileHandler']
+__all__ = ['CacheHandler', 'CacheFileHandler', 'MemoryCacheHandler']
 
 import errno
 import json
 import logging
+import os
+from spotipy.util import CLIENT_CREDS_ENV_VARS
 
 logger = logging.getLogger(__name__)
 
@@ -53,6 +55,7 @@ class CacheFileHandler(CacheHandler):
             self.cache_path = cache_path
         else:
             cache_path = ".cache"
+            username = (username or os.getenv(CLIENT_CREDS_ENV_VARS["client_username"]))
             if username:
                 cache_path += "-" + str(username)
             self.cache_path = cache_path
@@ -82,3 +85,24 @@ class CacheFileHandler(CacheHandler):
         except IOError:
             logger.warning('Couldn\'t write token to cache at: %s',
                            self.cache_path)
+
+
+class MemoryCacheHandler(CacheHandler):
+    """
+    A cache handler that simply stores the token info in memory as an
+    instance attribute of this class. The token info will be lost when this
+    instance is freed.
+    """
+
+    def __init__(self, token_info=None):
+        """
+        Parameters:
+            * token_info: The token info to store in memory. Can be None.
+        """
+        self.token_info = token_info
+
+    def get_cached_token(self):
+        return self.token_info
+
+    def save_token_to_cache(self, token_info):
+        self.token_info = token_info
diff --git a/tests/unit/test_oauth.py b/tests/unit/test_oauth.py
index 9acdcc9..192daa6 100644
--- a/tests/unit/test_oauth.py
+++ b/tests/unit/test_oauth.py
@@ -6,7 +6,7 @@ import unittest
 import six.moves.urllib.parse as urllibparse
 
 from spotipy import SpotifyOAuth, SpotifyImplicitGrant, SpotifyPKCE
-from spotipy.cache_handler import CacheHandler
+from spotipy.cache_handler import MemoryCacheHandler
 from spotipy.oauth2 import SpotifyClientCredentials, SpotifyOauthError
 from spotipy.oauth2 import SpotifyStateError
 
@@ -51,18 +51,6 @@ def _make_pkceauth(*args, **kwargs):
     return SpotifyPKCE("CLID", "REDIR", "STATE", *args, **kwargs)
 
 
-class MemoryCache(CacheHandler):
-    def __init__(self, token_info=None):
-        self.token_info = token_info
-
-    def get_cached_token(self):
-        return self.token_info
-
-    def save_token_to_cache(self, token_info):
-        self.token_info = token_info
-        return None
-
-
 class OAuthCacheTest(unittest.TestCase):
 
     @patch.multiple(SpotifyOAuth,
@@ -161,7 +149,7 @@ class OAuthCacheTest(unittest.TestCase):
         scope = "playlist-modify-private"
         tok = _make_fake_token(1, 1, scope)
 
-        spot = _make_oauth(scope, cache_handler=MemoryCache())
+        spot = _make_oauth(scope, cache_handler=MemoryCacheHandler())
         spot.cache_handler.save_token_to_cache(tok)
         cached_tok = spot.cache_handler.get_cached_token()