Throw NotImplementedError for FAILOVER (#1911)

* unsupported failover

* add test and docstring

* fix docstring

Author: dvora-h

redis/commands/core.py

@@ -1087,6 +1087,15 @@ def wait(self, num_replicas, timeout, **kwargs):
         """
         return self.execute_command("WAIT", num_replicas, timeout, **kwargs)
 
+    def failover(self):
+        """
+        This function throws a NotImplementedError since it is intentionally
+        not supported.
+        """
+        raise NotImplementedError(
+            "FAILOVER is intentionally not implemented in the client."
+        )
+
 
 class BasicKeyCommands:
     """

tests/test_commands.py

@@ -647,6 +647,11 @@ def test_config_set(self, r):
         assert r.config_set("timeout", 0)
         assert r.config_get()["timeout"] == "0"
 
+    @skip_if_server_version_lt("6.0.0")
+    def test_failover(self, r):
+        with pytest.raises(NotImplementedError):
+            r.failover()
+
     @pytest.mark.onlynoncluster
     def test_dbsize(self, r):
         r["a"] = "foo"