Add unittests for item movement code (#11885)

src/unittest/mock_inventorymanager.h

@@ -0,0 +1,41 @@
+/*
+Minetest
+Copyright (C) 2022 Minetest core developers & community
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include <gamedef.h>
+#include <inventorymanager.h>
+
+class MockInventoryManager : public InventoryManager
+{
+public:
+	MockInventoryManager(IGameDef *gamedef) :
+		p1(gamedef->getItemDefManager()),
+		p2(gamedef->getItemDefManager())
+	{};
+
+	virtual Inventory* getInventory(const InventoryLocation &loc){
+		if (loc.type == InventoryLocation::PLAYER && loc.name == "p1")
+			return &p1;
+		if (loc.type == InventoryLocation::PLAYER && loc.name == "p2")
+			return &p2;
+		return nullptr;
+	}
+
+	Inventory p1;
+	Inventory p2;
+};