test for non-flake build regressions

this adds a nixos vm test doing a deploy on a nix which does not have
flakes enabled, to guard against this breaking as it has done before [1].

The existing test infrastructure is changed slightly to make enabling
flakes configurable inside the vm's config.

[1] https://github.com/serokell/deploy-rs/pull/272

1 files changed, 3 insertions, 2 deletions

diff --git a/nix/tests/common.nix b/nix/tests/common.nix
index 37abb5d..9e5f363 100644
--- a/nix/tests/common.nix
+++ b/nix/tests/common.nix
@@ -2,11 +2,12 @@
 #
 # SPDX-License-Identifier: MPL-2.0
 
-{inputs, pkgs, ...}: {
+{inputs, pkgs, flakes, ...}: {
   nix = {
     registry.nixpkgs.flake = inputs.nixpkgs;
+    nixPath = [ "nixpkgs=${inputs.nixpkgs}" ];
     extraOptions = ''
-      experimental-features = nix-command flakes
+      experimental-features = ${if flakes then "nix-command flakes" else "nix-command"}
     '';
     settings = {
       trusted-users = [ "root" "@wheel" ];