nixosTests: Add allDrivers for development purposes

nixos/tests/all-tests.nix

@@ -26,8 +26,22 @@ let
     featureFlags.minimalModules = {};
   };
   evalMinimalConfig = module: nixosLib.evalModules { modules = [ module ]; };
-in
-{
+
+  allDrivers = getDrivers tests;
+
+  getDrivers = ts:
+    if isDerivation ts
+    then ts.driver or null
+    else if isAttrs ts
+    then recurseIntoAttrs (mapAttrs (k: getDrivers) ts)
+    else null;
+
+  tests = {
+
+  # for typechecking of the scripts and evaluation of
+  # the nodes, without running VMs.
+  inherit allDrivers;
+
   _3proxy = handleTest ./3proxy.nix {};
   acme = handleTest ./acme.nix {};
   adguardhome = handleTest ./adguardhome.nix {};
@@ -620,4 +634,5 @@ in
   zookeeper = handleTest ./zookeeper.nix {};
   zrepl = handleTest ./zrepl.nix {};
   zsh-history = handleTest ./zsh-history.nix {};
-}
+};
+in tests