Inventory: Send dirty lists where appropriate (#8742)

This change reduces the amount of sent data towards clients. Inventory lists that are already known to the player are skipped, saving quite some data over time.

Raises protocol version to 38 to ensure correct backwards-compatible code.

16 files changed, 193 insertions, 160 deletions

diff --git a/src/client/client.cpp b/src/client/client.cpp
index e78b9bb8a..4c5485325 100644
--- a/src/client/client.cpp
+++ b/src/client/client.cpp
@@ -557,8 +557,8 @@ void Client::step(float dtime)
 		if (count_after != count_before) {
 			// Do this every <interval> seconds after TOCLIENT_INVENTORY
 			// Reset the locally changed inventory to the authoritative inventory
-			m_env.getLocalPlayer()->inventory = *m_inventory_from_server;
-			m_inventory_updated = true;
+			player->inventory = *m_inventory_from_server;
+			m_update_wielded_item = true;
 		}
 	}
 
@@ -1331,28 +1331,30 @@ void Client::setPlayerControl(PlayerControl &control)
 void Client::setPlayerItem(u16 item)
 {
 	m_env.getLocalPlayer()->setWieldIndex(item);
-	m_inventory_updated = true;
+	m_update_wielded_item = true;
 
 	NetworkPacket pkt(TOSERVER_PLAYERITEM, 2);
 	pkt << item;
 	Send(&pkt);
 }
 
-// Returns true if the inventory of the local player has been
-// updated from the server. If it is true, it is set to false.
-bool Client::getLocalInventoryUpdated()
+// Returns true once after the inventory of the local player
+// has been updated from the server.
+bool Client::updateWieldedItem()
 {
-	bool updated = m_inventory_updated;
-	m_inventory_updated = false;
-	return updated;
-}
+	if (!m_update_wielded_item)
+		return false;
+
+	m_update_wielded_item = false;
 
-// Copies the inventory of the local player to parameter
-void Client::getLocalInventory(Inventory &dst)
-{
 	LocalPlayer *player = m_env.getLocalPlayer();
 	assert(player);
-	dst = player->inventory;
+	if (auto *list = player->inventory.getList("main"))
+		list->setModified(false);
+	if (auto *list = player->inventory.getList("hand"))
+		list->setModified(false);
+
+	return true;
 }
 
 Inventory* Client::getInventory(const InventoryLocation &loc)
diff --git a/src/client/client.h b/src/client/client.h
index 3bfb1631e..85456fe4d 100644
--- a/src/client/client.h
+++ b/src/client/client.h
@@ -274,9 +274,7 @@ public:
 
 	// Returns true if the inventory of the local player has been
 	// updated from the server. If it is true, it is set to false.
-	bool getLocalInventoryUpdated();
-	// Copies the inventory of the local player to parameter
-	void getLocalInventory(Inventory &dst);
+	bool updateWieldedItem();
 
 	/* InventoryManager interface */
 	Inventory* getInventory(const InventoryLocation &loc) override;
@@ -504,7 +502,7 @@ private:
 	// If 0, server init hasn't been received yet.
 	u16 m_proto_ver = 0;
 
-	bool m_inventory_updated = false;
+	bool m_update_wielded_item = false;
 	Inventory *m_inventory_from_server = nullptr;
 	float m_inventory_from_server_age = 0.0f;
 	PacketCounter m_packetcounter;
diff --git a/src/client/game.cpp b/src/client/game.cpp
index 4d5fbfb97..5bf41bcd6 100644
--- a/src/client/game.cpp
+++ b/src/client/game.cpp
@@ -599,7 +599,6 @@ struct GameRunData {
 	bool dig_instantly;
 	bool digging_blocked;
 	bool left_punch;
-	bool update_wielded_item_trigger;
 	bool reset_jump_timer;
 	float nodig_delay_timer;
 	float dig_time;
@@ -1018,7 +1017,6 @@ bool Game::startup(bool *kill,
 	// Reinit runData
 	runData = GameRunData();
 	runData.time_from_last_punch = 10.0;
-	runData.update_wielded_item_trigger = true;
 
 	m_game_ui->initFlags();
 
@@ -3736,19 +3734,11 @@ void Game::updateFrame(ProfilerGraph *graph, RunStats *stats, f32 dtime,
 	if (player->getWieldIndex() != runData.new_playeritem)
 		client->setPlayerItem(runData.new_playeritem);
 
-	// Update local inventory if it has changed
-	if (client->getLocalInventoryUpdated()) {
-		//infostream<<"Updating local inventory"<<std::endl;
-		runData.update_wielded_item_trigger = true;
-	}
-
-	if (runData.update_wielded_item_trigger) {
+	if (client->updateWieldedItem()) {
 		// Update wielded tool
 		ItemStack selected_item, hand_item;
 		ItemStack &tool_item = player->getWieldedItem(&selected_item, &hand_item);
 		camera->wield(tool_item);
-
-		runData.update_wielded_item_trigger = false;
 	}
 
 	/*
diff --git a/src/inventory.cpp b/src/inventory.cpp
index f2cc2ede3..375f0f147 100644
--- a/src/inventory.cpp
+++ b/src/inventory.cpp
@@ -20,6 +20,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "inventory.h"
 #include "serialization.h"
 #include "debug.h"
+#include <algorithm>
 #include <sstream>
 #include "log.h"
 #include "itemdef.h"
@@ -382,27 +383,32 @@ void InventoryList::clearItems()
 		m_items.emplace_back();
 	}
 
-	//setDirty(true);
+	setModified();
 }
 
 void InventoryList::setSize(u32 newsize)
 {
-	if(newsize != m_items.size())
-		m_items.resize(newsize);
+	if (newsize == m_items.size())
+		return;
+
+	m_items.resize(newsize);
 	m_size = newsize;
+	setModified();
 }
 
 void InventoryList::setWidth(u32 newwidth)
 {
 	m_width = newwidth;
+	setModified();
 }
 
 void InventoryList::setName(const std::string &name)
 {
 	m_name = name;
+	setModified();
 }
 
-void InventoryList::serialize(std::ostream &os) const
+void InventoryList::serialize(std::ostream &os, bool incremental) const
 {
 	//os.imbue(std::locale("C"));
 
@@ -415,6 +421,9 @@ void InventoryList::serialize(std::ostream &os) const
 			os<<"Item ";
 			item.serialize(os);
 		}
+		// TODO: Implement this:
+		// if (!incremental || item.checkModified())
+		// os << "Keep";
 		os<<"\n";
 	}
 
@@ -424,8 +433,8 @@ void InventoryList::serialize(std::ostream &os) const
 void InventoryList::deSerialize(std::istream &is)
 {
 	//is.imbue(std::locale("C"));
+	setModified();
 
-	clearItems();
 	u32 item_i = 0;
 	m_width = 0;
 
@@ -439,12 +448,12 @@ void InventoryList::deSerialize(std::istream &is)
 		std::string name;
 		std::getline(iss, name, ' ');
 
-		if (name == "EndInventoryList")
-			return;
-
-		// This is a temporary backwards compatibility fix
-		if (name == "end")
+		if (name == "EndInventoryList" || name == "end") {
+			// If partial incremental: Clear leftover items (should not happen!)
+			for (size_t i = item_i; i < m_items.size(); ++i)
+				m_items[i].clear();
 			return;
+		}
 
 		if (name == "Width") {
 			iss >> m_width;
@@ -464,6 +473,8 @@ void InventoryList::deSerialize(std::istream &is)
 			if(item_i > getSize() - 1)
 				throw SerializationError("too many items");
 			m_items[item_i++].clear();
+		} else if (name == "Keep") {
+			++item_i; // Unmodified item
 		}
 	}
 
@@ -557,7 +568,7 @@ ItemStack InventoryList::changeItem(u32 i, const ItemStack &newitem)
 
 	ItemStack olditem = m_items[i];
 	m_items[i] = newitem;
-	//setDirty(true);
+	setModified();
 	return olditem;
 }
 
@@ -565,6 +576,7 @@ void InventoryList::deleteItem(u32 i)
 {
 	assert(i < m_items.size()); // Pre-condition
 	m_items[i].clear();
+	setModified();
 }
 
 ItemStack InventoryList::addItem(const ItemStack &newitem_)
@@ -612,8 +624,8 @@ ItemStack InventoryList::addItem(u32 i, const ItemStack &newitem)
 		return newitem;
 
 	ItemStack leftover = m_items[i].addItem(newitem, m_itemdef);
-	//if(leftover != newitem)
-	//	setDirty(true);
+	if (leftover != newitem)
+		setModified();
 	return leftover;
 }
 
@@ -682,8 +694,8 @@ ItemStack InventoryList::takeItem(u32 i, u32 takecount)
 		return ItemStack();
 
 	ItemStack taken = m_items[i].takeItem(takecount);
-	//if(!taken.empty())
-	//	setDirty(true);
+	if (!taken.empty())
+		setModified();
 	return taken;
 }
 
@@ -788,16 +800,6 @@ void Inventory::clear()
 	m_lists.clear();
 }
 
-void Inventory::clearContents()
-{
-	m_dirty = true;
-	for (InventoryList *list : m_lists) {
-		for (u32 j=0; j<list->getSize(); j++) {
-			list->deleteItem(j);
-		}
-	}
-}
-
 Inventory::Inventory(IItemDefManager *itemdef)
 {
 	m_dirty = false;
@@ -807,7 +809,6 @@ Inventory::Inventory(IItemDefManager *itemdef)
 Inventory::Inventory(const Inventory &other)
 {
 	*this = other;
-	m_dirty = false;
 }
 
 Inventory & Inventory::operator = (const Inventory &other)
@@ -838,11 +839,15 @@ bool Inventory::operator == (const Inventory &other) const
 	return true;
 }
 
-void Inventory::serialize(std::ostream &os) const
+void Inventory::serialize(std::ostream &os, bool incremental) const
 {
-	for (InventoryList *list : m_lists) {
-		os<<"List "<<list->getName()<<" "<<list->getSize()<<"\n";
-		list->serialize(os);
+	for (const InventoryList *list : m_lists) {
+		if (!incremental || list->checkModified()) {
+			os << "List " << list->getName() << " " << list->getSize() << "\n";
+			list->serialize(os, incremental);
+		} else {
+			os << "KeepList " << list->getName() << "\n";
+		}
 	}
 
 	os<<"EndInventory\n";
@@ -850,7 +855,8 @@ void Inventory::serialize(std::ostream &os) const
 
 void Inventory::deSerialize(std::istream &is)
 {
-	clear();
+	std::vector<InventoryList *> new_lists;
+	new_lists.reserve(m_lists.size());
 
 	while (is.good()) {
 		std::string line;
@@ -861,12 +867,20 @@ void Inventory::deSerialize(std::istream &is)
 		std::string name;
 		std::getline(iss, name, ' ');
 
-		if (name == "EndInventory")
-			return;
+		if (name == "EndInventory" || name == "end") {
+			// Remove all lists that were not sent
+			for (auto &list : m_lists) {
+				if (std::find(new_lists.begin(), new_lists.end(), list) != new_lists.end())
+					continue;
 
-		// This is a temporary backwards compatibility fix
-		if (name == "end")
+				delete list;
+				list = nullptr;
+				m_dirty = true;
+			}
+			m_lists.erase(std::remove(m_lists.begin(), m_lists.end(),
+					nullptr), m_lists.end());
 			return;
+		}
 
 		if (name == "List") {
 			std::string listname;
@@ -875,15 +889,33 @@ void Inventory::deSerialize(std::istream &is)
 			std::getline(iss, listname, ' ');
 			iss>>listsize;
 
-			InventoryList *list = new InventoryList(listname, listsize, m_itemdef);
+			InventoryList *list = getList(listname);
+			bool create_new = !list;
+			if (create_new)
+				list = new InventoryList(listname, listsize, m_itemdef);
+			else
+				list->setSize(listsize);
 			list->deSerialize(is);
 
-			m_lists.push_back(list);
-		}
-		else
-		{
-			throw SerializationError("invalid inventory specifier: " + name);
+			new_lists.push_back(list);
+			if (create_new)
+				m_lists.push_back(list);
+
+		} else if (name == "KeepList") {
+			// Incrementally sent list
+			std::string listname;
+			std::getline(iss, listname, ' ');
+
+			InventoryList *list = getList(listname);
+			if (list) {
+				new_lists.push_back(list);
+			} else {
+				errorstream << "Inventory::deSerialize(): Tried to keep list '" <<
+					listname << "' which is non-existent." << std::endl;
+			}
 		}
+		// Any additional fields will throw errors when received by a client
+		// older than PROTOCOL_VERSION 38
 	}
 
 	// Contents given to deSerialize() were not terminated properly: throw error.
diff --git a/src/inventory.h b/src/inventory.h
index 3f299993a..b7a93553d 100644
--- a/src/inventory.h
+++ b/src/inventory.h
@@ -194,7 +194,7 @@ public:
 	void setSize(u32 newsize);
 	void setWidth(u32 newWidth);
 	void setName(const std::string &name);
-	void serialize(std::ostream &os) const;
+	void serialize(std::ostream &os, bool incremental) const;
 	void deSerialize(std::istream &is);
 
 	InventoryList(const InventoryList &other);
@@ -265,12 +265,16 @@ public:
 	// also with optional rollback recording
 	void moveItemSomewhere(u32 i, InventoryList *dest, u32 count);
 
+	inline bool checkModified() const { return m_dirty; }
+	inline void setModified(bool dirty = true) { m_dirty = dirty; }
+
 private:
 	std::vector<ItemStack> m_items;
 	std::string m_name;
 	u32 m_size;
 	u32 m_width = 0;
 	IItemDefManager *m_itemdef;
+	bool m_dirty = true;
 };
 
 class Inventory
@@ -279,7 +283,6 @@ public:
 	~Inventory();
 
 	void clear();
-	void clearContents();
 
 	Inventory(IItemDefManager *itemdef);
 	Inventory(const Inventory &other);
@@ -290,7 +293,8 @@ public:
 		return !(*this == other);
 	}
 
-	void serialize(std::ostream &os) const;
+	// Never ever serialize to disk using "incremental"!
+	void serialize(std::ostream &os, bool incremental = false) const;
 	void deSerialize(std::istream &is);
 
 	InventoryList * addList(const std::string &name, u32 size);
@@ -301,28 +305,35 @@ public:
 	// A shorthand for adding items. Returns leftover item (possibly empty).
 	ItemStack addItem(const std::string &listname, const ItemStack &newitem)
 	{
-		m_dirty = true;
 		InventoryList *list = getList(listname);
 		if(list == NULL)
 			return newitem;
 		return list->addItem(newitem);
 	}
 
-	bool checkModified() const
+	inline bool checkModified() const
 	{
-		return m_dirty;
+		if (m_dirty)
+			return true;
+
+		for (const auto &list : m_lists)
+			if (list->checkModified())
+				return true;
+
+		return false;
 	}
 
-	void setModified(const bool x)
+	inline void setModified(bool dirty)
 	{
-		m_dirty = x;
+		m_dirty = dirty;
+		for (const auto &list : m_lists)
+			list->setModified(dirty);
 	}
-
 private:
 	// -1 if not found
 	const s32 getListIndex(const std::string &name) const;
 
 	std::vector<InventoryList*> m_lists;
 	IItemDefManager *m_itemdef;
-	bool m_dirty = false;
+	bool m_dirty = true;
 };
diff --git a/src/network/clientpackethandler.cpp b/src/network/clientpackethandler.cpp
index 520fcfa81..91829474e 100644
--- a/src/network/clientpackethandler.cpp
+++ b/src/network/clientpackethandler.cpp
@@ -333,7 +333,7 @@ void Client::handleCommand_Inventory(NetworkPacket* pkt)
 
 	player->inventory.deSerialize(is);
 
-	m_inventory_updated = true;
+	m_update_wielded_item = true;
 
 	delete m_inventory_from_server;
 	m_inventory_from_server = new Inventory(player->inventory);
diff --git a/src/network/networkprotocol.h b/src/network/networkprotocol.h
index 451518bbf..05737d0a9 100644
--- a/src/network/networkprotocol.h
+++ b/src/network/networkprotocol.h
@@ -195,9 +195,12 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 		ContentFeatures version 13
 		Add full Euler rotations instead of just yaw
 		Add TOCLIENT_PLAYER_SPEED
+	PROTOCOL VERSION 38:
+		Incremental inventory sending mode
+		Unknown inventory serialization fields no longer throw an error
 */
 
-#define LATEST_PROTOCOL_VERSION 37
+#define LATEST_PROTOCOL_VERSION 38
 #define LATEST_PROTOCOL_VERSION_STRING TOSTRING(LATEST_PROTOCOL_VERSION)
 
 // Server's supported network protocol range
diff --git a/src/network/serverpackethandler.cpp b/src/network/serverpackethandler.cpp
index 5ad60f48a..1965d87aa 100644
--- a/src/network/serverpackethandler.cpp
+++ b/src/network/serverpackethandler.cpp
@@ -732,7 +732,7 @@ void Server::handleCommand_InventoryAction(NetworkPacket* pkt)
 	// Eat the action
 	delete a;
 
-	SendInventory(playersao);
+	SendInventory(playersao, true);
 }
 
 void Server::handleCommand_ChatMessage(NetworkPacket* pkt)
@@ -1310,7 +1310,7 @@ void Server::handleCommand_Interact(NetworkPacket *pkt)
 
 			// Apply returned ItemStack
 			if (playersao->setWieldedItem(item)) {
-				SendInventory(playersao);
+				SendInventory(playersao, true);
 			}
 		}
 
@@ -1346,7 +1346,7 @@ void Server::handleCommand_Interact(NetworkPacket *pkt)
 				item, playersao, pointed)) {
 			// Apply returned ItemStack
 			if (playersao->setWieldedItem(item)) {
-				SendInventory(playersao);
+				SendInventory(playersao, true);
 			}
 		}
 
@@ -1364,7 +1364,7 @@ void Server::handleCommand_Interact(NetworkPacket *pkt)
 		if (m_script->item_OnSecondaryUse(
 				item, playersao)) {
 			if( playersao->setWieldedItem(item)) {
-				SendInventory(playersao);
+				SendInventory(playersao, true);
 			}
 		}
 	} // action == INTERACT_ACTIVATE
diff --git a/src/remoteplayer.h b/src/remoteplayer.h
index ea118e604..260504fb4 100644
--- a/src/remoteplayer.h
+++ b/src/remoteplayer.h
@@ -110,12 +110,7 @@ public:
 
 	bool checkModified() const { return m_dirty || inventory.checkModified(); }
 
-	void setModified(const bool x)
-	{
-		m_dirty = x;
-		if (!x)
-			inventory.setModified(x);
-	}
+	inline void setModified(const bool x) { m_dirty = x; }
 
 	void setLocalAnimations(v2s32 frames[4], float frame_speed)
 	{
diff --git a/src/script/lua_api/l_object.cpp b/src/script/lua_api/l_object.cpp
index be2172f1b..68cc1c0a9 100644
--- a/src/script/lua_api/l_object.cpp
+++ b/src/script/lua_api/l_object.cpp
@@ -355,7 +355,7 @@ int ObjectRef::l_set_wielded_item(lua_State *L)
 	ItemStack item = read_item(L, 2, getServer(L)->idef());
 	bool success = co->setWieldedItem(item);
 	if (success && co->getType() == ACTIVEOBJECT_TYPE_PLAYER) {
-		getServer(L)->SendInventory(((PlayerSAO*)co));
+		getServer(L)->SendInventory((PlayerSAO *)co, true);
 	}
 	lua_pushboolean(L, success);
 	return 1;
diff --git a/src/server.cpp b/src/server.cpp
index 871612e60..59bc12581 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -1057,7 +1057,7 @@ PlayerSAO* Server::StageTwoClientInit(session_t peer_id)
 	SendPlayerInventoryFormspec(peer_id);
 
 	// Send inventory
-	SendInventory(playersao);
+	SendInventory(playersao, false);
 
 	// Send HP or death screen
 	if (playersao->isDead())
@@ -1241,19 +1241,22 @@ void Server::setInventoryModified(const InventoryLocation &loc, bool playerSend)
 		break;
 	case InventoryLocation::PLAYER:
 	{
-		if (!playerSend)
-			return;
 
 		RemotePlayer *player = m_env->getPlayer(loc.name.c_str());
 
 		if (!player)
 			return;
 
+		player->setModified(true);
+
+		if (!playerSend)
+			return;
+
 		PlayerSAO *playersao = player->getPlayerSAO();
 		if(!playersao)
 			return;
 
-		SendInventory(playersao);
+		SendInventory(playersao, true);
 	}
 		break;
 	case InventoryLocation::NODEMETA:
@@ -1527,21 +1530,27 @@ void Server::SendNodeDef(session_t peer_id,
 	Non-static send methods
 */
 
-void Server::SendInventory(PlayerSAO* playerSAO)
+void Server::SendInventory(PlayerSAO *sao, bool incremental)
 {
-	UpdateCrafting(playerSAO->getPlayer());
+	RemotePlayer *player = sao->getPlayer();
+
+	// Do not send new format to old clients
+	incremental &= player->protocol_version >= 38;
+
+	UpdateCrafting(player);
 
 	/*
 		Serialize it
 	*/
 
-	NetworkPacket pkt(TOCLIENT_INVENTORY, 0, playerSAO->getPeerID());
-
-	std::ostringstream os;
-	playerSAO->getInventory()->serialize(os);
+	NetworkPacket pkt(TOCLIENT_INVENTORY, 0, sao->getPeerID());
 
-	std::string s = os.str();
+	std::ostringstream os(std::ios::binary);
+	sao->getInventory()->serialize(os, incremental);
+	sao->getInventory()->setModified(false);
+	player->setModified(true);
 
+	const std::string &s = os.str();
 	pkt.putRawString(s.c_str(), s.size());
 	Send(&pkt);
 }
@@ -2595,8 +2604,9 @@ void Server::sendDetachedInventory(const std::string &name, session_t peer_id)
 		// Serialization & NetworkPacket isn't a love story
 		std::ostringstream os(std::ios_base::binary);
 		inv_it->second->serialize(os);
+		inv_it->second->setModified(false);
 
-		std::string os_str = os.str();
+		const std::string &os_str = os.str();
 		pkt << static_cast<u16>(os_str.size()); // HACK: to keep compatibility with 5.0.0 clients
 		pkt.putRawString(os_str);
 	}
@@ -2822,6 +2832,11 @@ void Server::UpdateCrafting(RemotePlayer *player)
 	if (!clist || clist->getSize() == 0)
 		return;
 
+	if (!clist->checkModified()) {
+		verbosestream << "Skip Server::UpdateCrafting(): list unmodified" << std::endl;
+		return;
+	}
+
 	// Get a preview for crafting
 	ItemStack preview;
 	InventoryLocation loc;
diff --git a/src/server.h b/src/server.h
index 06adbad68..d1dcafac3 100644
--- a/src/server.h
+++ b/src/server.h
@@ -333,7 +333,7 @@ public:
 
 	void SendPlayerHPOrDie(PlayerSAO *player, const PlayerHPChangeReason &reason);
 	void SendPlayerBreath(PlayerSAO *sao);
-	void SendInventory(PlayerSAO* playerSAO);
+	void SendInventory(PlayerSAO *playerSAO, bool incremental);
 	void SendMovePlayer(session_t peer_id);
 	void SendPlayerSpeed(session_t peer_id, const v3f &added_vel);
 
diff --git a/src/unittest/test_inventory.cpp b/src/unittest/test_inventory.cpp
index 1a783afae..5f71636c4 100644
--- a/src/unittest/test_inventory.cpp
+++ b/src/unittest/test_inventory.cpp
@@ -33,8 +33,9 @@ public:
 
 	void testSerializeDeserialize(IItemDefManager *idef);
 
-	static const char *serialized_inventory;
-	static const char *serialized_inventory_2;
+	static const char *serialized_inventory_in;
+	static const char *serialized_inventory_out;
+	static const char *serialized_inventory_inc;
 };
 
 static TestInventory g_test_instance;
@@ -49,7 +50,7 @@ void TestInventory::runTests(IGameDef *gamedef)
 void TestInventory::testSerializeDeserialize(IItemDefManager *idef)
 {
 	Inventory inv(idef);
-	std::istringstream is(serialized_inventory, std::ios::binary);
+	std::istringstream is(serialized_inventory_in, std::ios::binary);
 
 	inv.deSerialize(is);
 	UASSERT(inv.getList("0"));
@@ -62,82 +63,64 @@ void TestInventory::testSerializeDeserialize(IItemDefManager *idef)
 
 	inv.getList("main")->setWidth(5);
 	std::ostringstream inv_os(std::ios::binary);
-	inv.serialize(inv_os);
-	UASSERTEQ(std::string, inv_os.str(), serialized_inventory_2);
+	inv.serialize(inv_os, false);
+	UASSERTEQ(std::string, inv_os.str(), serialized_inventory_out);
+
+	inv.setModified(false);
+	inv_os.str("");
+	inv_os.clear();
+	inv.serialize(inv_os, true);
+	UASSERTEQ(std::string, inv_os.str(), serialized_inventory_inc);
+
+	ItemStack leftover = inv.getList("main")->takeItem(7, 99 - 12);
+	ItemStack wanted = ItemStack("default:dirt", 99 - 12, 0, idef);
+	UASSERT(leftover == wanted);
+	leftover = inv.getList("main")->getItem(7);
+	wanted.count = 12;
+	UASSERT(leftover == wanted);
 }
 
-const char *TestInventory::serialized_inventory =
-	"List 0 32\n"
+const char *TestInventory::serialized_inventory_in =
+	"List 0 10\n"
 	"Width 3\n"
 	"Empty\n"
 	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
 	"Item default:cobble 61\n"
 	"Empty\n"
 	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
 	"Item default:dirt 71\n"
 	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
 	"Item default:dirt 99\n"
 	"Item default:cobble 38\n"
 	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
+	"EndInventoryList\n"
+	"List abc 1\n"
+	"Item default:stick 3\n"
+	"Width 0\n"
 	"EndInventoryList\n"
 	"EndInventory\n";
 
-const char *TestInventory::serialized_inventory_2 =
-	"List main 32\n"
+const char *TestInventory::serialized_inventory_out =
+	"List main 10\n"
 	"Width 5\n"
 	"Empty\n"
 	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
 	"Item default:cobble 61\n"
 	"Empty\n"
 	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
 	"Item default:dirt 71\n"
 	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
 	"Item default:dirt 99\n"
 	"Item default:cobble 38\n"
 	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
-	"Empty\n"
 	"EndInventoryList\n"
+	"List abc 1\n"
+	"Width 0\n"
+	"Item default:stick 3\n"
+	"EndInventoryList\n"
+	"EndInventory\n";
+
+const char *TestInventory::serialized_inventory_inc =
+	"KeepList main\n"
+	"KeepList abc\n"
 	"EndInventory\n";
diff --git a/src/unittest/test_servermodmanager.cpp b/src/unittest/test_servermodmanager.cpp
index 72ac7c6bf..0757323f4 100644
--- a/src/unittest/test_servermodmanager.cpp
+++ b/src/unittest/test_servermodmanager.cpp
@@ -20,6 +20,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "test.h"
 #include <algorithm>
 #include "server/mods.h"
+#include "settings.h"
 #include "test_config.h"
 
 class TestServerModManager : public TestBase
@@ -85,6 +86,10 @@ void TestServerModManager::runTests(IGameDef *gamedef)
 
 void TestServerModManager::testCreation()
 {
+	std::string path = std::string(TEST_WORLDDIR) + DIR_DELIM + "world.mt";
+	Settings world_config;
+	world_config.set("gameid", "minimal");
+	UASSERTEQ(bool, world_config.updateConfigFile(path.c_str()), true);
 	ServerModManager sm(TEST_WORLDDIR);
 }
 
diff --git a/src/unittest/test_world/do_not_remove.txt b/src/unittest/test_world/do_not_remove.txt
new file mode 100644
index 000000000..e69de29bb
--- /dev/null
+++ b/src/unittest/test_world/do_not_remove.txt
diff --git a/src/unittest/test_world/world.mt b/src/unittest/test_world/world.mt
deleted file mode 100644
index ab9b5413a..000000000
--- a/src/unittest/test_world/world.mt
+++ /dev/null
@@ -1 +0,0 @@
-gameid = minimal