nixos/tests: add predictable-interface-names.nix (#34305)

nixos/tests/predictable-interface-names.nix

@@ -0,0 +1,27 @@
+{ system ? builtins.currentSystem
+, pkgs ? import ../.. { inherit system; }
+}:
+with import ../lib/testing.nix { inherit system; };
+let boolToString = x: if x then "yes" else "no"; in
+let testWhenSetTo = predictable: withNetworkd:
+makeTest {
+  name = "${if predictable then "" else "un"}predictableInterfaceNames${if withNetworkd then "-with-networkd" else ""}";
+  meta = {};
+
+  machine = { config, pkgs, ... }: {
+    networking.usePredictableInterfaceNames = pkgs.stdenv.lib.mkForce predictable;
+    networking.useNetworkd = withNetworkd;
+    networking.dhcpcd.enable = !withNetworkd;
+  };
+
+  testScript = ''
+    print $machine->succeed("ip link");
+    $machine->succeed("ip link show ${if predictable then "ens3" else "eth0"}");
+    $machine->fail("ip link show ${if predictable then "eth0" else "ens3"}");
+  '';
+}; in
+with pkgs.stdenv.lib.lists;
+with pkgs.stdenv.lib.attrsets;
+listToAttrs (map (drv: nameValuePair drv.name drv) (
+crossLists testWhenSetTo [[true false] [true false]]
+))