Add unittests for item movement code (#11885)

src/unittest/mock_activeobject.h

@@ -0,0 +1,31 @@
+/*
+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 <activeobject.h>
+
+class MockActiveObject : public ActiveObject
+{
+public:
+	MockActiveObject(u16 id) : ActiveObject(id) {}
+
+	virtual ActiveObjectType getType() const { return ACTIVEOBJECT_TYPE_TEST; }
+	virtual bool getCollisionBox(aabb3f *toset) const { return false; }
+	virtual bool getSelectionBox(aabb3f *toset) const { return false; }
+	virtual bool collideWithObjects() const { return false; }
+};