Add support for EVAL_RO (redis#1862)

* add sort_ro

* mark test as onlynon cluster

* delete mark test as onlynoncluster

* add eval_ro

* fix linters

* delete sort_ro

* fix pr comment

* add type hints

* add type hints

* linters

Author: dvora-h

redis/commands/core.py

@@ -3917,7 +3917,12 @@ class ScriptCommands:
     https://redis.com/ebook/part-3-next-steps/chapter-11-scripting-redis-with-lua/
     """
 
-    def eval(self, script, numkeys, *keys_and_args):
+    def _eval(
+        self, command: str, script: str, numkeys: int, *keys_and_args: list
+    ) -> str:
+        return self.execute_command(command, script, numkeys, *keys_and_args)
+
+    def eval(self, script: str, numkeys: int, *keys_and_args: list) -> str:
         """
         Execute the Lua ``script``, specifying the ``numkeys`` the script
         will touch and the key names and argument values in ``keys_and_args``.
@@ -3928,7 +3933,19 @@ def eval(self, script, numkeys, *keys_and_args):
 
         For more information check  https://redis.io/commands/eval
         """
-        return self.execute_command("EVAL", script, numkeys, *keys_and_args)
+        return self._eval("EVAL", script, numkeys, *keys_and_args)
+
+    def eval_ro(self, script: str, numkeys: int, *keys_and_args: list) -> str:
+        """
+        The read-only variant of the EVAL command
+
+        Execute the read-only Lue ``script`` specifying the ``numkeys`` the script
+        will touch and the key names and argument values in ``keys_and_args``.
+        Returns the result of the script.
+
+        For more information check  https://redis.io/commands/eval_ro
+        """
+        return self._eval("EVAL_RO", script, numkeys, *keys_and_args)
 
     def evalsha(self, sha, numkeys, *keys_and_args):
         """

tests/test_scripting.py

@@ -1,5 +1,6 @@
 import pytest
 
+import redis
 from redis import exceptions
 from tests.conftest import skip_if_server_version_lt
 
@@ -31,6 +32,13 @@ def test_eval(self, r):
         # 2 * 3 == 6
         assert r.eval(multiply_script, 1, "a", 3) == 6
 
+    # @skip_if_server_version_lt("7.0.0") turn on after redis 7 release
+    def test_eval_ro(self, unstable_r):
+        unstable_r.set("a", "b")
+        assert unstable_r.eval_ro("return redis.call('GET', KEYS[1])", 1, "a") == b"b"
+        with pytest.raises(redis.ResponseError):
+            unstable_r.eval_ro("return redis.call('DEL', KEYS[1])", 1, "a")
+
     @skip_if_server_version_lt("6.2.0")
     def test_script_flush_620(self, r):
         r.set("a", 2)