printer json BUGFIX empty (leaf-)list print fixes

Tests included.

Author: michalvasko

src/printer_json.c

@@ -734,7 +734,9 @@ json_print_inner(struct jsonpr_ctx *pctx, const struct lyd_node *node)
         while (snode) {
             /* print an empty (leaf-)list */
             LY_CHECK_RET(json_print_leaf_list_empty(pctx, snode));
+            pctx->level_printed = pctx->level;
 
+            /* next iter */
             snode = json_print_next_empty_leaf_list(pctx, snode->next, NULL);
         }
     }
@@ -1083,6 +1085,7 @@ static LY_ERR
 json_print_node(struct jsonpr_ctx *pctx, const struct lyd_node *node)
 {
     const struct lysc_node *snode;
+    ly_bool last_inst = 0;
 
     if (!lyd_node_should_print(node, pctx->options)) {
         if (json_print_array_is_last_inst(pctx, node)) {
@@ -1118,6 +1121,13 @@ json_print_node(struct jsonpr_ctx *pctx, const struct lyd_node *node)
         }
 
         if (pctx->options & LYD_PRINT_EMPTY_LEAF_LIST) {
+            /* first check whether the last instance of a schema node has been printed */
+            if (!node->next || (node->schema != node->next->schema)) {
+                last_inst = 1;
+            }
+        }
+
+        if (last_inst) {
             snode = json_print_next_empty_leaf_list(pctx, node->schema->next, node);
             while (snode) {
                 /* print an empty (leaf-)list */

tests/utests/data/test_printer_json.c

@@ -1,9 +1,10 @@
 /**
  * @file test_printer_json.c
  * @author: Radek Krejci <[email protected]>
+ * @author Michal Vasko <[email protected]>
  * @brief unit tests for functions from printer_yang.c
  *
- * Copyright (c) 2019-2020 CESNET, z.s.p.o.
+ * Copyright (c) 2019 - 2025 CESNET, z.s.p.o.
  *
  * This source code is licensed under BSD 3-Clause License (the "License").
  * You may not use this file except in compliance with the License.
@@ -34,6 +35,12 @@ setup(void **state)
             "          type string;"
             "        }"
             "      }"
+            "      list l2 {"
+            "        key \"k2\";"
+            "        leaf k2 {"
+            "          type string;"
+            "        }"
+            "      }"
             "    }"
             "    leaf-list ll {"
             "      type string;"
@@ -96,7 +103,14 @@ test_empty_leaf_list(void **state)
     data = "{\"schema2:a\":{\"b\":{\"c\":\"val\"}}}";
     CHECK_PARSE_LYD_PARAM(data, LYD_JSON, 0, LYD_VALIDATE_PRESENT, LY_SUCCESS, tree);
     assert_int_equal(LY_SUCCESS, lyd_print_mem(&buffer, tree, LYD_JSON, LYD_PRINT_SHRINK | LYD_PRINT_EMPTY_LEAF_LIST));
-    CHECK_STRING(buffer, "{\"schema2:a\":{\"b\":{\"c\":\"val\",\"l\":[]},\"ll\":[]},\"schema2:tl\":[]}");
+    CHECK_STRING(buffer, "{\"schema2:a\":{\"b\":{\"c\":\"val\",\"l\":[],\"l2\":[]},\"ll\":[]},\"schema2:tl\":[]}");
+    free(buffer);
+    lyd_free_all(tree);
+
+    data = "{\"schema2:a\":{\"b\":{\"l\":[{\"k\":\"key1\"},{\"k\":\"key2\"}]}}}";
+    CHECK_PARSE_LYD_PARAM(data, LYD_JSON, 0, LYD_VALIDATE_PRESENT, LY_SUCCESS, tree);
+    assert_int_equal(LY_SUCCESS, lyd_print_mem(&buffer, tree, LYD_JSON, LYD_PRINT_SHRINK | LYD_PRINT_EMPTY_LEAF_LIST));
+    CHECK_STRING(buffer, "{\"schema2:a\":{\"b\":{\"l\":[{\"k\":\"key1\"},{\"k\":\"key2\"}],\"l2\":[]},\"ll\":[]},\"schema2:tl\":[]}");
     free(buffer);
     lyd_free_all(tree);
 
@@ -107,6 +121,8 @@ test_empty_leaf_list(void **state)
             "  \"schema2:a\": {\n"
             "    \"b\": {\n"
             "      \"l\": [\n"
+            "      ],\n"
+            "      \"l2\": [\n"
             "      ]\n"
             "    },\n"
             "    \"ll\": [\n"