testers.testEqualDerivation: move from build-support/test-equal-derivation.nix

pkgs/applications/misc/hello/default.nix

@@ -3,7 +3,7 @@
 , fetchurl
 , nixos
 , testVersion
-, testEqualDerivation
+, testers
 , hello
 }:
 
@@ -22,7 +22,7 @@ stdenv.mkDerivation rec {
     version = testVersion { package = hello; };
 
     invariant-under-noXlibs =
-      testEqualDerivation
+      testers.testEqualDerivation
         "hello must not be rebuilt when environment.noXlibs is set."
         hello
         (nixos { environment.noXlibs = true; }).pkgs.hello;

pkgs/build-support/testers/default.nix

@@ -0,0 +1,4 @@
+{ pkgs, lib, callPackage }:
+{
+  testEqualDerivation = callPackage ./test-equal-derivation.nix { };
+}

pkgs/top-level/all-packages.nix

@@ -904,6 +904,8 @@ with pkgs;
   # lib functions depending on pkgs
   inherit (import ../pkgs-lib { inherit lib pkgs; }) formats;
 
+  testers = callPackage ../build-support/testers {};
+
   ### TOOLS
 
   _3llo = callPackage ../tools/misc/3llo { };
@@ -10650,8 +10652,6 @@ with pkgs;
 
   termplay = callPackage ../tools/misc/termplay { };
 
-  testEqualDerivation = callPackage ../build-support/test-equal-derivation.nix { };
-
   tetrd = callPackage ../applications/networking/tetrd { };
 
   tewisay = callPackage ../tools/misc/tewisay { };