WIP: test: Set up service tests

modules/default.nix

@@ -1 +1,6 @@
-{ imports = [ ./crowdsec ]; }
+{
+  imports = [
+    ./crowdsec
+    ./serviceTests.nix
+  ];
+}

modules/serviceTests.nix

@@ -0,0 +1,20 @@
+/**
+  Module to make writing service-specific tests easy.
+*/
+{ lib, ... }:
+let
+  inherit (lib) mkOption types;
+in
+{
+  options = {
+    serviceTests = mkOption {
+      type = types.attrsOf types.package;
+
+      description = ''
+        NixOS tests to run.
+      '';
+
+      default = { };
+    };
+  };
+}