feat: add tests for DaveGamble#842

Add some tests for setting NULL to deallocated pointers
releated to DaveGamble#842 and DaveGamble#833

tests/CMakeLists.txt

@@ -62,6 +62,7 @@ if(ENABLE_CJSON_TEST)
 
     option(ENABLE_VALGRIND OFF "Enable the valgrind memory checker for the tests.")
     if (ENABLE_VALGRIND)
+        add_compile_definitions(ENABLE_VALGRIND)
         find_program(MEMORYCHECK_COMMAND valgrind)
         if ("${MEMORYCHECK_COMMAND}" MATCHES "MEMORYCHECK_COMMAND-NOTFOUND")
             message(WARNING "Valgrind couldn't be found.")

tests/misc_tests.c

@@ -732,6 +732,23 @@ static void cjson_set_bool_value_must_not_break_objects(void)
     cJSON_Delete(sobj);
 }
 
+static void deallocated_pointers_should_be_set_to_null(void)
+{
+    /* deallocated pointers should be set to null */
+    /* however, valgrind on linux reports when attempting to access a freed memory, we have to skip it */
+#ifndef ENABLE_VALGRIND
+    cJSON *string = cJSON_CreateString("item");
+    cJSON *root = cJSON_CreateObject();
+
+    cJSON_Delete(string);
+    free(string->valuestring);
+
+    cJSON_AddObjectToObject(root, "object");
+    cJSON_Delete(root->child);
+    free(root->child->string);
+#endif
+}
+
 int CJSON_CDECL main(void)
 {
     UNITY_BEGIN();
@@ -762,6 +779,7 @@ int CJSON_CDECL main(void)
     RUN_TEST(cjson_delete_item_from_array_should_not_broken_list_structure);
     RUN_TEST(cjson_set_valuestring_to_object_should_not_leak_memory);
     RUN_TEST(cjson_set_bool_value_must_not_break_objects);
+    RUN_TEST(deallocated_pointers_should_be_set_to_null);
 
     return UNITY_END();
 }