1 files changed, 58 insertions, 3 deletions
diff --git a/nixpkgs/nixos/modules/misc/nixpkgs/test.nix b/nixpkgs/nixos/modules/misc/nixpkgs/test.nix
index ec5fab9fb4a5..9e8851707f8f 100644
--- a/nixpkgs/nixos/modules/misc/nixpkgs/test.nix
+++ b/nixpkgs/nixos/modules/misc/nixpkgs/test.nix
@@ -1,8 +1,63 @@
 { evalMinimalConfig, pkgs, lib, stdenv }:
+let
+  eval = mod: evalMinimalConfig {
+    imports = [ ../nixpkgs.nix mod ];
+  };
+  withHost = eval {
+    nixpkgs.hostPlatform = "aarch64-linux";
+  };
+  withHostAndBuild = eval {
+    nixpkgs.hostPlatform = "aarch64-linux";
+    nixpkgs.buildPlatform = "aarch64-darwin";
+  };
+  ambiguous = {
+    _file = "ambiguous.nix";
+    nixpkgs.hostPlatform = "aarch64-linux";
+    nixpkgs.buildPlatform = "aarch64-darwin";
+    nixpkgs.system = "x86_64-linux";
+    nixpkgs.localSystem.system = "x86_64-darwin";
+    nixpkgs.crossSystem.system = "i686-linux";
+    imports = [
+      { _file = "repeat.nix";
+        nixpkgs.hostPlatform = "aarch64-linux";
+      }
+    ];
+  };
+  getErrors = module:
+    let
+      uncheckedEval = lib.evalModules { modules = [ ../nixpkgs.nix module ]; };
+    in map (ass: ass.message) (lib.filter (ass: !ass.assertion) uncheckedEval.config.assertions);
+in
 lib.recurseIntoAttrs {
   invokeNixpkgsSimple =
-    (evalMinimalConfig ({ config, modulesPath, ... }: {
-      imports = [ (modulesPath + "/misc/nixpkgs.nix") ];
+    (eval {
       nixpkgs.system = stdenv.hostPlatform.system;
-    }))._module.args.pkgs.hello;
+    })._module.args.pkgs.hello;
+  assertions =
+    assert withHost._module.args.pkgs.stdenv.hostPlatform.system == "aarch64-linux";
+    assert withHost._module.args.pkgs.stdenv.buildPlatform.system == "aarch64-linux";
+    assert withHostAndBuild._module.args.pkgs.stdenv.hostPlatform.system == "aarch64-linux";
+    assert withHostAndBuild._module.args.pkgs.stdenv.buildPlatform.system == "aarch64-darwin";
+    assert builtins.trace (lib.head (getErrors ambiguous))
+      getErrors ambiguous ==
+        [''
+          Your system configures nixpkgs with the platform parameters:
+          nixpkgs.hostPlatform, with values defined in:
+            - repeat.nix
+            - ambiguous.nix
+          nixpkgs.buildPlatform, with values defined in:
+            - ambiguous.nix
+
+          However, it also defines the legacy options:
+          nixpkgs.system, with values defined in:
+            - ambiguous.nix
+          nixpkgs.localSystem, with values defined in:
+            - ambiguous.nix
+          nixpkgs.crossSystem, with values defined in:
+            - ambiguous.nix
+
+          For a future proof system configuration, we recommend to remove
+          the legacy definitions.
+        ''];
+    pkgs.emptyFile;
 }