Merge pull request #430 from Jovian-Experiments/fix/no-op-oversight

.github/workflows/no-op.yml

@@ -0,0 +1,15 @@
+name: Module No-Op
+on:
+  pull_request:
+  push:
+jobs:
+  eval:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/[email protected]
+
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@v4
+
+      - name: Verify module is a No-Op
+        run: nix-instantiate ./support/nix-tests/check-no-ops.nix

modules/steamos/default.nix

@@ -1,4 +1,4 @@
-{ lib, ... }:
+{ lib, config, ... }:
 
 let
   inherit (lib)
@@ -19,7 +19,8 @@ in
     jovian.steamos = {
       useSteamOSConfig = mkOption {
         type = types.bool;
-        default = true;
+        default = config.jovian.steam.enable;
+        defaultText = "config.jovian.steam.enable";
         description = ''
           Whether to enable opinionated system configuration from SteamOS.
 

support/nix-tests/check-no-ops.nix

@@ -0,0 +1,50 @@
+#!/usr/bin/env nix-instantiate
+#
+# SPDX-License-Identifier: MIT
+#
+# Author: Samuel Dionne-Riel
+#
+# What's this? A shebang and +x in my Nix expression??
+# ¯\_(ツ)_/¯
+#
+# Test that eval for unconfigured modules are no-ops.
+#
+# Origin: https://gitlab.com/samueldr/nixos-configuration/-/blob/cb5c6a1671ebeb1250e4f00e89787f15f45a37f1/modules/tests/check-no-ops.nix
+#
+
+let nixpkgs = ../../nixpkgs.nix; in
+{ pkgs ? import nixpkgs {} }:
+
+let
+  baseCfg = {
+    # Prevent stray warnings
+    system.stateVersion = "00.00";
+    # Ignore bootloader asserts
+    boot.isContainer = true;
+    # Manual builds will differ since new options are added. This is okay.
+    documentation.nixos.enable = false;
+  };
+  compareEvals = a: b: a.config.system.build.toplevel == b.config.system.build.toplevel;
+  evalConfig = cfg: (import (pkgs.path + "/nixos")) { configuration = { imports = [ cfg baseCfg ]; }; };
+  evalModule = module: evalConfig { imports = [ module ]; };
+  virginEval = evalConfig {};
+  modules = [
+    ../../modules
+  ];
+in
+map (modulePath:
+  let
+    moduleEval = evalConfig modulePath;
+    toplevel = moduleEval.config.system.build.toplevel;
+    vToplevel = virginEval.config.system.build.toplevel;
+  in
+  if !(compareEvals moduleEval virginEval)
+  then
+    builtins.throw ''
+      Module '${toString modulePath}' is not a no-op.
+             ${toString modulePath} != virginEval
+             ${toplevel} != ${vToplevel}
+    ''
+    toplevel
+  else toplevel
+) modules