From b2c87fbf98cf5d4a57cb4528cf60cabefc4d5282 Mon Sep 17 00:00:00 2001
From: Shea Levy <shea@shealevy.com>
Date: Wed, 12 Apr 2017 12:40:24 -0400
Subject: [PATCH] lib: Add test for composeExtensions

---
 lib/tests.nix | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/tests.nix b/lib/tests.nix
index 1a9a5accd1c..d93cadf2533 100644
--- a/lib/tests.nix
+++ b/lib/tests.nix
@@ -277,4 +277,14 @@ runTests {
     expected = [ "2001" "db8" "0" "0042" "" "8a2e" "370" "" ];
   };
 
+  testComposeExtensions = {
+    expr = let obj = makeExtensible (self: { foo = self.bar; });
+               f = self: super: { bar = false; baz = true; };
+               g = self: super: { bar = super.baz or false; };
+               f_o_g = composeExtensions f g;
+               composed = obj.extend f_o_g;
+           in composed.foo;
+    expected = true;
+  };
+
 }