Split checks off to their own file

To make it easier to add more.

checks.nix

@@ -0,0 +1,65 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+{
+  emacs29,
+  runCommand,
+  testers,
+  tmux,
+  writeText,
+  makeDoomPackages,
+}:
+let
+  common = {
+    # TODO: drop after NixOS 24.05 release.
+    emacs = emacs29;
+    doomLocalDir = "~/.local/share/nix-doom-unstraightened";
+  };
+  mkDoom = args: (makeDoomPackages (common // args)).doomEmacs;
+  doomTest = assertion: args: testers.testEqualContents {
+    inherit assertion;
+    expected = writeText "doom-expected" "Doom functions";
+    # Runs Doom in tmux, waiting (by polling) until its window disappears.
+    actual = runCommand "interactive" {
+      nativeBuildInputs = [ tmux (mkDoom args) ];
+    } ''
+      tmux new-session -s doom-testing -d
+      tmux new-window -n doom-window doom-emacs
+      for ((i = 0; i < 100; i++)); do
+        tmux list-windows -a | grep -q doom-window || break
+        sleep .1
+      done
+      tmux kill-session -t doom-testing
+      '';
+  };
+in {
+  minimal = mkDoom { doomDir = ./doomdirs/minimal; };
+  minimalEmacs = (makeDoomPackages (common // {
+    doomDir = ./doomdirs/minimal;
+  })).emacsWithDoom;
+  full = mkDoom {
+    full = true;
+    doomDir = ./doomdirs/minimal;
+  };
+  example = mkDoom { doomDir = ./doomdirs/example; };
+  example-without-loader = mkDoom {
+    doomDir = ./doomdirs/example;
+    profileName = "";
+  };
+  interactive = doomTest "minimal doom starts" { doomDir = ./doomdirs/test; };
+  interactive-without-loader = doomTest "minimal doom (without loader) starts" {
+    doomDir = ./doomdirs/test;
+    profileName = "";
+  };
+}

flake.nix

@@ -51,49 +51,8 @@
     in
       pkgs.callPackages self mergedArgs;
     in {
-      checks = perSystemPackages (pkgs:
+      checks = perSystemPackages (pkgs: pkgs.callPackages ./checks.nix {
-        let
+        makeDoomPackages = doomFromPackages pkgs;
-          common = {
-            # TODO: drop after NixOS 24.05 release.
-            emacs = pkgs.emacs29;
-            doomLocalDir = "~/.local/share/nix-doom-unstraightened";
-          };
-          mkDoom = args: (doomFromPackages pkgs (common // args)).doomEmacs;
-          doomTest = assertion: args: pkgs.testers.testEqualContents {
-            inherit assertion;
-            expected = pkgs.writeText "doom-expected" "Doom functions";
-            # Runs Doom in tmux, waiting (by polling) until its window disappears.
-            actual = pkgs.runCommand "interactive" {
-              nativeBuildInputs = [ pkgs.tmux (mkDoom args) ];
-            } ''
-              tmux new-session -s doom-testing -d
-              tmux new-window -n doom-window doom-emacs
-              for ((i = 0; i < 100; i++)); do
-                tmux list-windows -a | grep -q doom-window || break
-                sleep .1
-              done
-              tmux kill-session -t doom-testing
-            '';
-          };
-        in {
-          minimal = mkDoom { doomDir = ./doomdirs/minimal; };
-          minimalEmacs = (doomFromPackages pkgs (common // {
-            doomDir = ./doomdirs/minimal;
-          })).emacsWithDoom;
-          full = mkDoom {
-            full = true;
-            doomDir = ./doomdirs/minimal;
-          };
-          example = mkDoom { doomDir = ./doomdirs/example; };
-          example-without-loader = mkDoom {
-            doomDir = ./doomdirs/example;
-            profileName = "";
-          };
-          interactive = doomTest "minimal doom starts" { doomDir = ./doomdirs/test; };
-          interactive-without-loader = doomTest "minimal doom (without loader) starts" {
-            doomDir = ./doomdirs/test;
-            profileName = "";
-          };
       });
       packages = perSystemPackages (pkgs: {
         doom-example = (doomFromPackages pkgs {