Start using Nix as a reproducible build tool

nix/tests/default.nix

@@ -0,0 +1,4 @@
+{ pkgs, makeTest, inputs }:
+{
+  vmTest = import ./nixos-module { inherit pkgs makeTest inputs; };
+}

nix/tests/nixos-module/default.nix

@@ -0,0 +1,25 @@
+{ pkgs, makeTest, inputs }:
+makeTest {
+  nodes = {
+    client = { config, pkgs, ... }: {
+      environment.systemPackages = [ pkgs.curl ];
+    };
+    lnbits = { ... }: {
+      imports = [ inputs.self.nixosModules.${pkgs.hostPlatform.system}.default ];
+      services.lnbits = {
+        enable = true;
+        openFirewall = true;
+        host = "0.0.0.0";
+      };
+    };
+  };
+  testScript = { nodes, ... }: ''
+    start_all()
+    lnbits.wait_for_open_port(${toString nodes.lnbits.config.services.lnbits.port})
+    client.wait_for_unit("multi-user.target")
+    with subtest("Check that the lnbits webserver can be reached."):
+        assert "<title>LNbits</title>" in client.succeed(
+            "curl -sSf http:/lnbits:8231/ | grep title"
+        )
+  '';
+}