From 23b3177402dfc0ed8228bf9f5fecd1672d5f7ec3 Mon Sep 17 00:00:00 2001
From: Eman Resu <78693624+quatquatt@users.noreply.github.com>
Date: Sun, 21 Jun 2026 18:04:34 -0400
Subject: [PATCH] lib.attrsets.concatMapAttrs: add test for handling duplicates

(cherry picked from commit f3e6fa555f71f2a4c87e51d457a1eeabcde459a8)
---
 lib/tests/misc.nix | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/lib/tests/misc.nix b/lib/tests/misc.nix
index e2872dcafce9..eeba768a902f 100644
--- a/lib/tests/misc.nix
+++ b/lib/tests/misc.nix
@@ -2164,6 +2164,21 @@ runTests {
     };
   };
 
+  testConcatMapAttrsDuplicates = {
+    expr =
+      concatMapAttrs
+        (name: value: {
+          final = value;
+        })
+        {
+          a = 1;
+          b = 2;
+        };
+    expected = {
+      final = 2;
+    };
+  };
+
   testFilterAttrs = {
     expr = filterAttrs (n: v: n != "a" && (v.hello or false) == true) {
       a.hello = true;