add test.open_world

dev/tests/example.lua

@@ -1,8 +1,20 @@
+-- Create/close/open/close world
+
+-- Open
 test.new_world("demo", "2019", "core:default")
 assert(world.is_open())
 assert(world.get_generator() == "core:default")
 test.sleep(1)
 assert(world.get_total_time() > 0.0)
 print(world.get_total_time())
+
+-- Close
 test.close_world(true)
 assert(not world.is_open())
+
+-- Reopen
+test.open_world("demo")
+assert(world.is_open())
+assert(world.get_total_time() > 0.0)
+test.tick()
+test.close_world(true)

res/scripts/stdlib.lua

@@ -13,6 +13,7 @@ if test then
     test.sleep = sleep
     test.name = __VC_TEST_NAME
     test.new_world = core.new_world
+    test.open_world = core.open_world
     test.close_world = core.close_world
     test.reconfig_packs = core.reconfig_packs
     test.tick = coroutine.yield

src/world/World.cpp

@@ -133,10 +133,12 @@ std::unique_ptr<Level> World::load(
         auto playerRoot = files::read_json(file);
         level->players->deserialize(playerRoot);
 
+        if (!playerRoot["players"].empty()) {
             if (!playerRoot["players"][0].has("id")) {
                 level->getWorld()->getInfo().nextPlayerId++;
             }
         }
+    }
     return level;
 }