/** One TCP port a child binds, on the address it binds it to. */
export interface PortBinding {
    port: number;
    host: string;
}
/**
 * Resolve when `binding` can be bound right now; reject, naming the port and the
 * OS error code, when it cannot. Binds briefly and closes again at once.
 *
 * Any bind error counts as "unavailable", not just `EADDRINUSE`: on Windows a
 * port held with `SO_EXCLUSIVEADDRUSE` (which libuv sets on every TCP bind) can
 * answer `EACCES` instead, and a child launched onto a port that fails either way
 * would die on it.
 */
export declare function assertPortFree(binding: PortBinding): Promise<void>;