Return a copy of the respnse from cache (#3106)

Author: dvora-h

redis/_cache.py

@@ -1,3 +1,4 @@
+import copy
 import random
 import time
 from collections import OrderedDict, defaultdict
@@ -226,7 +227,7 @@ def get(self, command: str) -> ResponseT:
                 self.delete(command)
                 return
             self._update_access(command)
-            return self.cache[command]["response"]
+            return copy.deepcopy(self.cache[command]["response"])
 
     def delete(self, command: str):
         """

tests/test_asyncio/test_cache.py

@@ -131,6 +131,17 @@ async def test_cache_blacklist(self, r):
         assert cache.get(("LLEN", "mylist")) is None
         assert cache.get(("LINDEX", "mylist", 1)) == b"bar"
 
+    @pytest.mark.parametrize("r", [{"cache": _LocalCache()}], indirect=True)
+    async def test_cache_return_copy(self, r):
+        r, cache = r
+        await r.lpush("mylist", "foo", "bar", "baz")
+        assert await r.lrange("mylist", 0, -1) == [b"baz", b"bar", b"foo"]
+        res = cache.get(("LRANGE", "mylist", 0, -1))
+        assert res == [b"baz", b"bar", b"foo"]
+        res.append(b"new")
+        check = cache.get(("LRANGE", "mylist", 0, -1))
+        assert check == [b"baz", b"bar", b"foo"]
+
 
 @pytest.mark.skipif(HIREDIS_AVAILABLE, reason="PythonParser only")
 @pytest.mark.onlycluster

tests/test_cache.py

@@ -15,6 +15,7 @@ def r(request):
         redis.Redis, request, protocol=3, client_cache=cache, **kwargs
     ) as client:
         yield client, cache
+        # client.flushdb()
 
 
 @pytest.mark.skipif(HIREDIS_AVAILABLE, reason="PythonParser only")
@@ -134,6 +135,17 @@ def test_cache_blacklist(self, r):
         assert cache.get(("LLEN", "mylist")) is None
         assert cache.get(("LINDEX", "mylist", 1)) == b"bar"
 
+    @pytest.mark.parametrize("r", [{"cache": _LocalCache()}], indirect=True)
+    def test_cache_return_copy(self, r):
+        r, cache = r
+        r.lpush("mylist", "foo", "bar", "baz")
+        assert r.lrange("mylist", 0, -1) == [b"baz", b"bar", b"foo"]
+        res = cache.get(("LRANGE", "mylist", 0, -1))
+        assert res == [b"baz", b"bar", b"foo"]
+        res.append(b"new")
+        check = cache.get(("LRANGE", "mylist", 0, -1))
+        assert check == [b"baz", b"bar", b"foo"]
+
 
 @pytest.mark.skipif(HIREDIS_AVAILABLE, reason="PythonParser only")
 @pytest.mark.onlycluster