Add cross version test

Signed-off-by: Harkrishn Patro <[email protected]>

tests/assets/minimal-cluster.conf

@@ -0,0 +1,8 @@
+# Minimal configuration for testing.
+always-show-logo yes
+daemonize no
+pidfile /var/run/valkey.pid
+loglevel verbose
+enable-debug-command yes
+cluster-enabled yes
+enable-module-command yes

tests/unit/moduleapi/cross-version-cluster.tcl

@@ -0,0 +1,61 @@
+# Test cross version compatibility of cluster.
+#
+# Use minimal.conf to make sure we don't use any configs not supported on the old version.
+
+# To disable `SELECT` command to be ran on the server.
+set ::singledb 1
+
+tags {external:skip cluster modules} {
+
+# To run this test use the `--other-server-path` parameter and pass in a compatible server path supporting
+# SendClusterMessage module API. 
+#
+# ./runtest-moduleapi --single unit/moduleapi/cross-version-cluster --other-server-path tests/tmp/valkey-8-0/valkey-server
+#
+# Test cross version compatibility of cluster module send message API.
+start_server {config "minimal-cluster.conf" start-other-server 1} {
+    set testmodule [file normalize tests/modules/cluster.so]
+    r MODULE LOAD $testmodule
+    set other_node_name [r CLUSTER MYID]
+
+    start_server {config "minimal-cluster.conf"} {
+        r MODULE LOAD $testmodule
+
+        test "set up cluster" {
+            r CLUSTER MEET [srv -1 host] [srv -1 port] 
+
+            # Link establishment requires few PING-PONG between two nodes
+            wait_for_condition 50 100 {
+                [string match {*handshake*} [r CLUSTER NODES]] eq 0 &&
+                [string match {*handshake*} [r -1 CLUSTER NODES]] eq 0
+            } else {
+                puts [r CLUSTER NODES]
+                puts [r -1 CLUSTER NODES]
+                fail "Cluster meet stuck in handshake state"
+            }
+        }
+
+        test "Send cluster message via module from latest to other server" {
+            assert_equal OK [r test.pingall]
+            assert_match "*cluster_stats_messages_module_sent:1*" [r CLUSTER INFO]
+            wait_for_condition 50 100 {
+                [string match {*cluster_stats_messages_module_received:1*} [r -1 CLUSTER INFO]]
+            } else {
+                fail "Node didn't receive the message"
+            }
+        }
+
+        test "Send cluster message via module from other server to latest" {
+            r CONFIG resetstat
+            r -1 CONFIG resetstat
+            assert_equal OK [r -1 test.pingall]
+            assert_match "*cluster_stats_messages_module_sent:1*" [r -1 CLUSTER INFO]
+            wait_for_condition 50 100 {
+                [string match {*cluster_stats_messages_module_received:1*} [r CLUSTER INFO]]
+            } else {
+                fail "Node didn't receive the message"
+            }
+        }
+    }
+}
+}