lixPackageSets.*.lix: test the correct Lix in passthru.tests

Previously always the top-level lix package would be used, which is obviously
not what we want.

nixos/tests/installer.nix

@@ -632,6 +632,7 @@ let
       grubUseEfi ? false,
       enableOCR ? false,
       meta ? { },
+      passthru ? { },
       testSpecialisationConfig ? false,
       testFlakeSwitch ? false,
       testByAttrSwitch ? false,
@@ -644,7 +645,7 @@ let
       isEfi = bootLoader == "systemd-boot" || (bootLoader == "grub" && grubUseEfi);
     in
     makeTest {
-      inherit enableOCR;
+      inherit enableOCR passthru;
       name = "installer-" + name;
       meta = {
         # put global maintainers here, individuals go into makeInstallerTest fkt call
@@ -1109,10 +1110,12 @@ in
 
   # The (almost) simplest partitioning scheme: a swap partition and
   # one big filesystem partition.
-  simple = makeInstallerTest "simple" simple-test-config;
-  lix-simple = makeInstallerTest "simple" simple-test-config // {
-    selectNixPackage = pkgs: pkgs.lix;
-  };
+  simple = makeInstallerTest "simple" (
+    simple-test-config
+    // {
+      passthru.override = args: makeInstallerTest "simple" simple-test-config // args;
+    }
+  );
 
   switchToFlake = makeInstallerTest "switch-to-flake" simple-test-config-flake;
 

nixos/tests/nix/misc.nix

@@ -3,20 +3,16 @@
 
 let
   inherit (pkgs) lib;
-  tests = {
-    default = testsForPackage { nixPackage = pkgs.nix; };
-    lix = testsForPackage { nixPackage = pkgs.lix; };
-  };
+  tests.default = testsForPackage { nixPackage = pkgs.nix; };
 
-  testsForPackage =
-    args:
-    lib.recurseIntoAttrs {
-      # If the attribute is not named 'test'
-      # You will break all the universe on the release-*.nix side of things.
-      # `discoverTests` relies on `test` existence to perform a `callTest`.
-      test = testMiscFeatures args;
-      passthru.override = args': testsForPackage (args // args');
+  testsForPackage = args: {
+    # If the attribute is not named 'test'
+    # You will break all the universe on the release-*.nix side of things.
+    # `discoverTests` relies on `test` existence to perform a `callTest`.
+    test = testMiscFeatures args // {
+      passthru.override = args': (testsForPackage (args // args')).test;
     };
+  };
 
   testMiscFeatures =
     { nixPackage, ... }:

pkgs/tools/package-management/lix/common-lix.nix

@@ -347,8 +347,8 @@ stdenv.mkDerivation (finalAttrs: {
   passthru = {
     inherit aws-sdk-cpp boehmgc;
     tests = {
-      misc = nixosTests.nix-misc.lix;
-      installer = nixosTests.installer.lix-simple;
+      misc = nixosTests.nix-misc.default.passthru.override { nixPackage = finalAttrs.finalPackage; };
+      installer = nixosTests.installer.simple.override { selectNixPackage = _: finalAttrs.finalPackage; };
     };
   };