Networking

The fake runtime supports Roblox-style RemoteEvent and RemoteFunction instances. They route calls between the server environment and fake client Player instances.

Functions, threads, and instances outside the fake data model are replaced with nil in remote event arguments.

RemoteEvent

RemoteEvent supports:

• FireServer(...)
• FireClient(player, ...)
• FireAllClients(...)
• OnServerEvent
• OnClientEvent

RemoteFunction

RemoteFunction supports:

• InvokeServer(...)
• InvokeClient(player, ...)
• OnServerInvoke
• OnClientInvoke

Client-to-Server

For these events, a LocalPlayer is created automatically by default.

RemoteEvent

local remote = Instance.new("RemoteEvent", game:GetService("ReplicatedStorage"))
remote.Name = "Ping"

local received
remote.OnServerEvent:Connect(function(player, value)
    received = { player = player, value = value }
end)

remote:FireServer("hello")

assert(received.player == game:GetService("Players").LocalPlayer)
assert(received.value == "hello")

RemoteFunction

local remote = Instance.new("RemoteFunction", game:GetService("ReplicatedStorage"))
remote.Name = "Add"

remote.OnServerInvoke = function(player, a, b)
    return a + b
end

assert(remote:InvokeServer(2, 3) == 5)

InvokeServer errors when OnServerInvoke is not set. InvokeClient errors when the target player has no client handler.

Creating players

Unlike client-to-server events, server-side event calls require player instances. To create a fake Player instance, use env:addPlayer(config). It returns a Player instance with a Character, Backpack, and PlayerScripts.

Config:

• name: string; defaults to a generated string.
• userId: number; defaults to a generated user ID.
• localPlayer: boolean; if true, sets it as the environment's active local player and allows access through Players.LocalPlayer. Overrides the default LocalPlayer.
• createCharacter: boolean; if true, creates a character model under workspace and assigns Player.Character.
• character: Model; if not nil, uses this model as the character instead of a new one.
• runHooks: boolean; defaults to true. If false, skips Players.PlayerAdded and Player.CharacterAdded hooks.

Server-to-Client

Single-player events

If you only need to test events with one player, simply use OnClientEvent or OnClientInvoke with a player that has localPlayer = true.

local player = env:addPlayer({
    name = "Player",
    localPlayer = true
})

local remote = Instance.new("RemoteEvent", game:GetService("ReplicatedStorage"))
local n = 0

remote.OnClientEvent:Connect(function(player, value)
    n += 1
end)

remote:FireClient(player)
assert(n == 1)

Multi-player events

LocalPlayer cannot be used for multi-player tests. Thus, you must bind the event to each player object manually. The fake signal API exposes a ConnectPlayer method, which allows for different handlers for each player. Note that this method does not exist in the real Roblox API.

local player1 = env:addPlayer({
    name = "Player1"
})

local player2 = env:addPlayer({
    name = "Player2"
})

local player1Count = 0
local player2Count = 0

local remote = Instance.new("RemoteEvent", game:GetService("ReplicatedStorage"))

remote.OnClientEvent:ConnectPlayer(player1, function(num)
    player1Count += num
end)
remote.OnClientEvent:ConnectPlayer(player2, function(num)
    player2Count += num
end)

remote:FireClient(player1, 1)
remote:FireClient(player2, 3)

assert(player1Count == 1)
assert(player2Count == 3)

Diagnostics

Remote calls are recorded on the environment and can be read with env:inspectRemoteTraffic().

local env = getEnvironment()
local remote = Instance.new("RemoteEvent", game:GetService("ReplicatedStorage"))
remote.Name = "LogMe"

remote:FireServer("payload")

local traffic = env:inspectRemoteTraffic()
assert(traffic[#traffic].kind == "FireServer")
assert(traffic[#traffic].remoteName == "LogMe")

env:inspectRemoteTraffic() records fake remote traffic for RemoteEvent and RemoteFunction.