Handle key expiry in _ExpiringDict.__iter__

Fixes #135 and #185.

fakeredis.py

@@ -142,6 +142,11 @@ def copy(self):
         new_copy.update(self._dict)
         return new_copy
 
+    # Not strictly necessary, but MutableMapping implements it by popping one
+    # item at a time, which may have odd effects in _ExpiringDict.
+    def clear(self):
+        self._dict.clear()
+
 
 class _ExpiringDict(_StrKeyDict):
     def __getitem__(self, key):
@@ -183,6 +188,15 @@ def persist(self, key):
     def expiring(self, key):
         return self._dict[to_bytes(key)][1]
 
+    def __iter__(self):
+        def generator():
+            for key, (value, expiration) in iteritems(self._dict):
+                if expiration is not None and datetime.now() > expiration:
+                    continue
+                yield key
+
+        return generator()
+
 
 class _ZSet(_StrKeyDict):
     redis_type = b'zset'

test_fakeredis.py

@@ -1294,6 +1294,13 @@ def test_scan_all_in_single_call(self):
         self.assertEqual(set(actual[1]), set(all_keys))
         self.assertEqual(actual[0], 0)
 
+    @attr('slow')
+    def test_scan_expired_key(self):
+        self.redis.set('expiringkey', 'value')
+        self.redis.pexpire('expiringkey', 1)
+        sleep(1)
+        self.assertEqual(self.redis.scan()[1], [])
+
     def test_scard(self):
         self.redis.sadd('foo', 'member1')
         self.redis.sadd('foo', 'member2')