add integration test for worker

nix/checks/flake-module.nix

@@ -10,6 +10,7 @@
         in
         {
           master = import ./master.nix checkArgs;
+          worker = import ./worker.nix checkArgs;
         };
     };
 }

nix/checks/worker.nix

@@ -0,0 +1,21 @@
+(import ./lib.nix) {
+  name = "from-nixos";
+  nodes = {
+    # `self` here is set by using specialArgs in `lib.nix`
+    node1 = { self, config, pkgs, ... }: {
+      imports = [
+        self.nixosModules.buildbot-worker
+      ];
+      services.buildbot-nix.worker = {
+        enable = true;
+        workerPasswordFile = pkgs.writeText "password" "password";
+      };
+    };
+  };
+  # This is the test code that will check if our service is running correctly:
+  testScript = ''
+    start_all()
+    # wait for our service to start
+    node1.wait_for_unit("buildbot-worker")
+  '';
+}