neo4j: add neo4j test

nixos/tests/all-tests.nix

@@ -142,6 +142,7 @@ in
   nat.firewall = handleTest ./nat.nix { withFirewall = true; };
   nat.firewall-conntrack = handleTest ./nat.nix { withFirewall = true; withConntrackHelpers = true; };
   nat.standalone = handleTest ./nat.nix { withFirewall = false; };
+  neo4j = handleTest ./neo4j.nix {};
   netdata = handleTest ./netdata.nix {};
   networking.networkd = handleTest ./networking.nix { networkd = true; };
   networking.scripted = handleTest ./networking.nix { networkd = false; };

nixos/tests/neo4j.nix

@@ -0,0 +1,20 @@
+import ./make-test.nix {
+  name = "neo4j";
+
+  nodes = {
+    master =
+      { ... }:
+
+      {
+        services.neo4j.enable = true;
+      };
+  };
+
+  testScript = ''
+    startAll;
+
+    $master->waitForUnit("neo4j");
+    $master->sleep(20); # Hopefully this is long enough!!
+    $master->succeed("curl http://localhost:7474/");
+  '';
+}