MemoryPool calls the Allocator directly

extras/tests/Helpers/Allocators.hpp

@@ -0,0 +1,28 @@
+// ArduinoJson - https://arduinojson.org
+// Copyright © 2014-2023, Benoit BLANCHON
+// MIT License
+
+#pragma once
+
+#include <ArduinoJson/Memory/Allocator.hpp>
+
+struct FailingAllocator : ArduinoJson::Allocator {
+  static FailingAllocator* instance() {
+    static FailingAllocator allocator;
+    return &allocator;
+  }
+
+ private:
+  FailingAllocator() = default;
+  ~FailingAllocator() = default;
+
+  void* allocate(size_t) override {
+    return nullptr;
+  }
+
+  void deallocate(void*) override {}
+
+  void* reallocate(void*, size_t) override {
+    return nullptr;
+  }
+};