luau_coverage Module

Public Luau surface over the __luau_coverage Internal FFI namespace — LCOV-style coverage dump for Luau scripts.

Purpose

Wrap the raw __luau_coverage.* FFI namespace in a typed Luau table that gets auto-injected as _G.luau_coverage via the prelude. Only populated when the VM was constructed with coverage enabled (ZERO_LUAU_COVERAGE=1 or 2 at startup); otherwise the module returns a small stub so probing scripts don't crash on non-coverage builds.

Captures are written as LCOV with a sibling luau_sources/ directory containing source bytes and a manifest.json mapping chunk names to files — that's what the proxy /ui/coverage page renders.

Usage

if luau_coverage.level() > 0 then
    -- Exercise a scenario in isolation
    luau_coverage.reset()
    runScenario()
    local r = luau_coverage.dump_lcov("/tmp/scenario.lcov")
    print(r.records, "records,", r.bytes, "bytes,", r.sources_written, "sources")
end

Exports

• luau_coverage.dump_lcov(path) -> DumpResult — render LCOV + write.
• luau_coverage.level() -> number — compile-time coverage level.
• luau_coverage.reset() -> boolean — drop accumulated coverage.