diff --git a/doomdirs/test/config.el b/doomdirs/test/config.el
new file mode 100644
index 0000000..0de99da
--- /dev/null
+++ b/doomdirs/test/config.el
@@ -0,0 +1,27 @@
+;; -*- lexical-binding: t; -*-
+
+;; 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.
+
+;; Config file for integration tests.
+;;
+;; This tries to hook into startup as late as possible, write a sign of life
+;; (currently a string written to $out), and then exits.
+
+(defun test-doom ()
+  (let ((out (getenv "out")))
+    (write-region "Doom functions" nil out nil nil nil 'mustbenew))
+  (kill-emacs))
+
+(add-hook 'doom-after-init-hook 'test-doom)
diff --git a/doomdirs/test/init.el b/doomdirs/test/init.el
new file mode 100644
index 0000000..c99e78c
--- /dev/null
+++ b/doomdirs/test/init.el
@@ -0,0 +1,16 @@
+;; 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.
+
+;; Doom doesn't like a completely empty doom! block.
+(doom! :config default)
diff --git a/flake.nix b/flake.nix
index be93e7a..c09e1ea 100644
--- a/flake.nix
+++ b/flake.nix
@@ -59,6 +59,22 @@
             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 // {
@@ -73,6 +89,11 @@
             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 {