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Testing with Geode.Testing

Every Roblox service Geode uses sits behind an adapter with an in-memory mock, so game code built on Geode runs in Lune, without Roblox. Geode.Testing gives those mocks, with virtual time and fault injection.

A universe of servers​

A universe holds the data every mock server shares. Each server gets its own services, and stores take them through their services option. Time only moves when the test moves it, so tests that wait minutes run instantly and the same way every time.

local ReplicatedStorage = game:GetService("ReplicatedStorage")
local Geode = require(ReplicatedStorage.Packages.Geode)

local universe = Geode.Testing.universe()
local serverA = universe:server({ jobId = "A" })
local serverB = universe:server({ jobId = "B" })

local storeA = Geode.Profile.store({ name = "Players", template = { coins = 0 }, services = serverA })
local storeB = Geode.Profile.store({ name = "Players", template = { coins = 0 }, services = serverB })

universe.clock:run(function()
	local first = storeA:load("player_1")
	assert(first.ok)
	first.profile:increment("coins", 5)
	first.profile:release()

	local second = storeB:load("player_1")
	assert(second.ok and second.profile:get("coins") == 5)
	second.profile:release()
end)

universe.clock:run runs a function to completion on the virtual clock. universe.clock:advance(seconds) moves time forward and runs everything that came due, like autosaves.

Faults​

server:inject makes calls from one server fail, slow down, or race with another server's write, so error handling gets tested on purpose rather than by luck.

local ReplicatedStorage = game:GetService("ReplicatedStorage")
local Geode = require(ReplicatedStorage.Packages.Geode)

local universe = Geode.Testing.universe()
local server = universe:server()
local store = Geode.Profile.store({ name = "Players", template = { coins = 0 }, services = server })

-- The next two UpdateAsync calls are throttled, the scheduler retries them
server:inject({ method = "update", fault = "throttle", times = 2 })
-- The next one lands, then reports failure anyway, the way Roblox may
server:inject({ method = "update", fault = { landed = 501 }, times = 1 })

universe.clock:run(function()
	local result = store:load("player_1")
	assert(result.ok)
	result.profile:release()
end)

Other faults add latency, return any error code, or land another server's write first. server:setBudget caps a request budget, server:crash() kills a server mid flight, and server:shutdown() runs its BindToClose callbacks.

Players and clients​

Mock servers have players and clients too, so the beginner layer, purchases and replication can be tested end to end.

local ReplicatedStorage = game:GetService("ReplicatedStorage")
local Geode = require(ReplicatedStorage.Packages.Geode)

local universe = Geode.Testing.universe()
local server = universe:server()

local PlayerData = Geode.players({
	name = "TestPlayers",
	template = { coins = 0 },
	replicate = { coins = "owner" },
	services = server,
})

server:join(42)
local client = Geode.Client.start(server:client(42))
universe.clock:advance(1)
print(client:atom("coins"):get())

Live services​

The same adapter contract suites the mocks pass also run against live Roblox services, from Studio or headlessly through Open Cloud with lune run live. See tests/studio/README.md in the repository for the setup.