add nixos test

checks/flake-module.nix

@@ -0,0 +1,15 @@
+{ self, ... }: {
+  perSystem =
+    { pkgs
+    , ...
+    }: {
+      checks =
+        let
+          # this gives us a reference to our flake but also all flake inputs
+          checkArgs = { inherit self pkgs; };
+        in
+        {
+          test = import ./test.nix checkArgs;
+        };
+    };
+}

checks/lib.nix

@@ -0,0 +1,20 @@
+# tests/lib.nix
+# The first argument to this function is the test module itself
+test:
+# These arguments are provided by `flake.nix` on import, see checkArgs
+{ pkgs, self }:
+let
+  inherit (pkgs) lib;
+  # this imports the nixos library that contains our testing framework
+  nixos-lib = import (pkgs.path + "/nixos/lib") { };
+in
+(nixos-lib.runTest {
+  hostPkgs = pkgs;
+  # This speeds up the evaluation by skipping evaluating documentation (optional)
+  defaults.documentation.enable = lib.mkDefault false;
+  # This makes `self` available in the NixOS configuration of our virtual machines.
+  # This is useful for referencing modules or packages from your own flake
+  # as well as importing from other flakes.
+  node.specialArgs = { inherit self; };
+  imports = [ test ];
+}).config.result

checks/test.nix

@@ -0,0 +1,35 @@
+(import ./lib.nix) {
+  name = "nixos-wiki";
+  nodes = {
+    # `self` here is set by using specialArgs in `lib.nix`
+    wiki = { self, pkgs, config, ... }: {
+      imports = [
+        self.nixosModules.nixos-wiki
+      ];
+      security.acme.defaults.email = "admin@example.com";
+      services.nixos-wiki = {
+        hostname = "nixos-wiki.example.com";
+        adminPasswordFile = pkgs.writeText "adminPasswordFile" "Creation-Fabric-Untrimmed3";
+        githubClientId = "Iv1.95ed182c83df1d22";
+        githubClientSecretFile = pkgs.writeText "githubClientSecretFile" "secret";
+        emergencyContact = "nixos-wiki@thalheim.io";
+        passwordSender = "nixos-wiki@thalheim.io";
+        noReplyAddress = "nixos-wiki-no-reply@thalheim.io";
+      };
+      services.nginx.virtualHosts.${config.services.mediawiki.nginx.hostName} = {
+        enableACME = false;
+        forceSSL = false;
+      };
+    };
+  };
+  # This is the test code that will check if our service is running correctly:
+  testScript = ''
+    start_all()
+
+    machine.wait_for_unit("phpfpm-mediawiki.service")
+    machine.wait_for_unit("nginx.service")
+
+    page = machine.succeed("curl -vL http://localhost/")
+    assert "MediaWiki has been installed" in page
+  '';
+}

flake.nix

@@ -34,6 +34,7 @@
         inputs.treefmt-nix.flakeModule
         ./targets/flake-module.nix
         ./modules/flake-module.nix
+        ./checks/flake-module.nix
       ];
       perSystem = { config, pkgs, ... }: {
         treefmt = {