[#16223] RESP JSON.MGET fixed arity check

Author: rigazilla

server/resp/src/main/java/org/infinispan/server/resp/commands/json/JSONMGET.java

@@ -32,10 +32,6 @@ public JSONMGET() {
    @Override
    public CompletionStage<RespRequestHandler> perform(Resp3Handler handler, ChannelHandlerContext ctx,
                                                       List<byte[]> arguments) {
-      if (arguments.size() < 3) {
-         handler.writer().wrongArgumentNumber(this);
-         return handler.myStage();
-      }
       List<byte[]> keys = arguments.subList(0, arguments.size() - 1);
       // Getting path as list to match get() signature
       List<byte[]> paths = arguments.subList(arguments.size() - 1, arguments.size());

server/resp/src/test/java/org/infinispan/server/resp/JsonCommandsTest.java

@@ -1894,6 +1894,22 @@ public void testJSONMGET() {
       // var result = redis.jsonMGet(jpRoot, "not-a-json", key1, key2);
    }
 
+   @Test
+   public void testJSONMGETSingleKey() {
+      // Test for issue #16223: JSON.MGET should accept single key
+      String key1 = k();
+      JsonPath jpRoot = new JsonPath("$");
+      JsonValue jv1 = defaultJsonParser.createJsonValue("""
+            {"a":1, "b": 2, "nested": {"a": 3}, "c": null}
+            """);
+      redis.jsonSet(key1, jpRoot, jv1);
+
+      // Test with single key and JSONPath
+      List<JsonValue> result = redis.jsonMGet(new JsonPath("$..a"), key1);
+      assertThat(result).hasSize(1);
+      assertThat(result.get(0).toString()).isEqualTo("[1,3]");
+   }
+
    // Lettuce Json object doesn't implement comparison. Implementing here
    private boolean compareJSONGet(JsonValue result, JsonValue expected, JsonPath... paths) {
       ObjectMapper mapper = new ObjectMapper();