Extend test_async_metatable_registration

games/devtest/mods/unittests/async_env.lua

@@ -175,19 +175,34 @@ local function test_async_metatable_registration(cb)
 	if pcall(core.register_async_metatable, "__builtin:vector", {}) then
 		error("Illegal metatable overriding allowed")
 	end
+
+	local custom_metatable = {}
+	core.register_async_metatable("unittests:custom_metatable", custom_metatable)
+
+	core.handle_async(function(x)
+		-- unittests.custom_metatable is registered in inside_async_env.lua
+		return getmetatable(x) == unittests.custom_metatable, x
+	end, function(metatable_preserved_async, table_after_roundtrip)
+		if not metatable_preserved_async then
+			return cb("Custom metatable not preserved (main -> async)")
+		end
+		if getmetatable(table_after_roundtrip) ~= custom_metatable then
+			return cb("Custom metable not preserved (after roundtrip)")
+		end
+		cb()
+	end, setmetatable({}, custom_metatable))
 end
-unittests.register("test_async_metatable_registration", test_async_metatable_registration)
+unittests.register("test_async_metatable_registration", test_async_metatable_registration, {async=true})
 
 local function test_vector_preserve(cb)
 	local vec = vector.new(1, 2, 3)
 	core.handle_async(function(x)
 		return x[1]
 	end, function(ret)
-		if ret == vec then -- only succeeds if metatable was preserved
-			cb()
-		else
+		if ret ~= vec then -- fails if metatable was not preserved
 			return cb("Vector value mismatch")
 		end
+		cb()
 	end, {vec})
 end
 unittests.register("test_async_vector", test_vector_preserve, {async=true})

games/devtest/mods/unittests/inside_async_env.lua

@@ -2,6 +2,9 @@ unittests = {}
 
 core.log("info", "Hello World")
 
+unittests.custom_metatable = {}
+core.register_async_metatable("unittests:custom_metatable", unittests.custom_metatable)
+
 local function do_tests()
 	assert(core == minetest)
 	-- stuff that should not be here