From 00f5ae0602cb0b82fca5916fb1b68b6b2f4ea531 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <joerg@thalheim.io>
Date: Fri, 20 Mar 2026 12:23:35 +0100
Subject: [PATCH] nixos/testing: fix testScript eval for functions without
 `...`

The nspawn container support (23f1e6370d1e) added a `containers`
argument to the testScript caller. This breaks tests whose testScript
uses strict pattern matching without ellipsis, e.g. `{ nodes }:`,
since Nix rejects unexpected arguments.

Use `builtins.intersectAttrs` to only pass arguments the function
actually expects, making the caller forward-compatible with future
argument additions.

Fixes: 23f1e6370d1e ("nixos/test-driver: add support for nspawn containers")
---
 nixos/lib/testing/testScript.nix | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/nixos/lib/testing/testScript.nix b/nixos/lib/testing/testScript.nix
index bde7b78607b4..fe417c4a624c 100644
--- a/nixos/lib/testing/testScript.nix
+++ b/nixos/lib/testing/testScript.nix
@@ -14,6 +14,13 @@ in
   options = {
     testScript = mkOption {
       type = either str (functionTo str);
+      apply =
+        v:
+        if lib.isFunction v then
+          # Only pass args the testScript function expects.
+          args: v (builtins.intersectAttrs (lib.functionArgs v) args)
+        else
+          v;
       description = ''
         A series of python declarations and statements that you write to perform
         the test.