feat(WIP): add nixos tests - integration tests

outputs/x86_64-linux/nixos-tests/idols-ruby.nix

@@ -0,0 +1,37 @@
+{
+  inputs,
+  lib,
+  system,
+  genSpecialArgs,
+  nixos-modules,
+  # TODO: test home-manager too.
+  home-modules ? [],
+  myvars,
+  ...
+}: let
+  pkgs = import inputs.nixpkgs {
+    inherit system;
+    config.allowUnfree = true;
+  };
+in
+  pkgs.testers.runNixOSTest {
+    name = "NixOS Tests for Idols Ruby";
+
+    node = {
+      inherit pkgs;
+      specialArgs = genSpecialArgs system;
+      pkgsReadOnly = false;
+    };
+
+    nodes = {
+      ruby.imports = nixos-modules;
+    };
+
+    # Note that machine1 and machine2 are now available as
+    # Python objects and also as hostnames in the virtual network
+    testScript = ''
+      ruby.wait_for_unit("network-online.target")
+
+      ruby.succeed("curl https://baidu.com")
+    '';
+  }