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How to use Luau with Lux

This guide shows you how to create, run, and test a Luau project with Lux.

Declare the language​

Set lua = "luau" in your lux.toml:

lux.toml
package = "my-luau-project"
lua = "luau"

Install a runtime​

Install the Luau runtime:

lx --lua-version luau install-lua

Lux uses a luau or lune binary from your PATH when available, and builds luau from source otherwise. To prefer lune or a custom binary, set the LUAU variable:

lx --variables LUAU=lune --lua-version luau install-lua

Run the project​

Declare an entry point under [run], then run it:

lux.toml
[run]
args = ["src/main.luau"]
lx run

Under Luau, Lux resolves dependencies through a generated .luaurc rather than LUA_PATH. See How Lux supports Luau for the details.

Test the project​

lx test uses the tiniest framework by default for Luau projects. Place *.spec.luau (or *.spec.lua) files under test/ or tests/:

tests/greeting.spec.luau
return function(tiniest)
    local expect = tiniest.expect

    tiniest.test("says hello", function()
        expect(require("../src/greeting").hello("luau")).is("hello from luau")
    end)
end
lx test

Format, lint, and check​

lx fmt
lx lint
lx check

lx fmt formats Luau sources with stylua. lx lint and lx check run luau-analyze instead of luacheck.

Consume Luau packages from a Lua project​

Lux transpiles Luau packages to Lua when they are installed for a Lua runtime, so a Lua project can depend on them. Native dependencies are not supported in this case.

Use packages in a Roblox project​

See How to use Lux packages in a Roblox project to build a Rojo-servable Packages/ layout with lx build --preset rojo.