add lmove operation

fakeredis/_server.py

@@ -95,6 +95,10 @@ def __init__(self, value):
         assert isinstance(value, bytes)
         self.value = value
 
+    @classmethod
+    def decode(cls, value):
+        return value
+
 
 class SimpleError(Exception):
     """Exception that will be turned into a frontend-specific exception."""
@@ -1779,6 +1783,16 @@ def linsert(self, key, where, pivot, value):
     def llen(self, key):
         return len(key.value)
 
+    @command((Key(list, None), Key(list), SimpleString, SimpleString))
+    def lmove(self, first_list, second_list, src, dst):
+        if src not in [b'LEFT', b'RIGHT']:
+            raise SimpleError(SYNTAX_ERROR_MSG)
+        if dst not in [b'LEFT', b'RIGHT']:
+            raise SimpleError(SYNTAX_ERROR_MSG)
+        el = self.rpop(first_list) if src == b'RIGHT' else self.lpop(first_list)
+        self.lpush(second_list, el) if dst == b'LEFT' else self.rpush(second_list, el)
+        return el
+
     def _list_pop(self, get_slice, key, *args):
         """Implements lpop and rpop.
 

test/test_fakeredis.py

@@ -1256,6 +1256,57 @@ def test_linsert_wrong_type(r):
     with pytest.raises(redis.ResponseError):
         r.linsert('foo', 'after', 'bar', 'element')
 
+def test_lmove(r):
+    assert r.lmove('foo', 'bar', 'RIGHT', 'LEFT') is None
+    assert r.lpop('bar') is None
+    r.rpush('foo', 'one')
+    r.rpush('foo', 'two')
+    r.rpush('bar', 'one')
+
+    # RPOPLPUSH
+    assert r.lmove('foo', 'bar', 'RIGHT', 'LEFT') == b'two'
+    assert r.lrange('foo', 0, -1) == [b'one']
+    assert r.lrange('bar', 0, -1) == [b'two', b'one']
+    # LPOPRPUSH
+    assert r.lmove('bar', 'bar', 'LEFT', 'RIGHT') == b'two'
+    assert r.lrange('bar', 0, -1) == [b'one', b'two']
+    # RPOPRPUSH
+    r.rpush('foo', 'three')
+    assert r.lmove('foo', 'bar', 'RIGHT', 'RIGHT') == b'three'
+    assert r.lrange('foo', 0, -1) == [b'one']
+    assert r.lrange('bar', 0, -1) == [b'one', b'two', b'three']
+    # LPOPLPUSH
+    assert r.lmove('bar', 'foo', 'LEFT', 'LEFT') == b'one'
+    assert r.lrange('foo', 0, -1) == [b'one', b'one']
+    assert r.lrange('bar', 0, -1) == [b'two', b'three']
+
+    # Catch instances where we store bytes and strings inconsistently
+    # and thus bar = ['two', b'one']
+    assert r.lrem('bar', -1, 'two') == 1
+
+def test_lmove_to_nonexistent_destination(r):
+    r.rpush('foo', 'one')
+    assert r.lmove('foo', 'bar', 'RIGHT', 'LEFT') == b'one'
+    assert r.rpop('bar') == b'one'
+
+def test_lmove_expiry(r):
+    r.rpush('foo', 'one')
+    r.rpush('bar', 'two')
+    r.expire('bar', 10)
+    r.lmove('foo', 'bar', 'RIGHT', 'LEFT')
+    assert r.ttl('bar') > 0
+
+def test_lmove_wrong_type(r):
+    r.set('foo', 'bar')
+    r.rpush('list', 'element')
+    with pytest.raises(redis.ResponseError):
+        r.lmove('foo', 'list', 'RIGHT', 'LEFT')
+    assert r.get('foo') == b'bar'
+    assert r.lrange('list', 0, -1) == [b'element']
+    with pytest.raises(redis.ResponseError):
+        r.lmove('list', 'foo', 'RIGHT', 'LEFT')
+    assert r.get('foo') == b'bar'
+    assert r.lrange('list', 0, -1) == [b'element']
 
 def test_rpoplpush(r):
     assert r.rpoplpush('foo', 'bar') is None
@@ -5273,6 +5324,10 @@ def test_llen(self, r):
         with pytest.raises(redis.ConnectionError):
             r.llen('name')
 
+    def test_lmove(self, r):
+        with pytest.raises(redis.ConnectionError):
+            r.lmove(1, 2, 'LEFT', 'RIGHT')
+
     def test_lrem(self, r):
         with pytest.raises(redis.ConnectionError):
             r.lrem('name', 2, 2)