vault: add nixos test

nixos/release.nix

···
   tests.taskserver = callTest tests/taskserver.nix {};
   tests.tomcat = callTest tests/tomcat.nix {};
   tests.udisks2 = callTest tests/udisks2.nix {};
+  tests.vault = callTest tests/vault.nix {};
   tests.virtualbox = callSubTests tests/virtualbox.nix { system = "x86_64-linux"; };
   tests.wordpress = callTest tests/wordpress.nix {};
   tests.xfce = callTest tests/xfce.nix {};

nixos/tests/vault.nix

···
+import ./make-test.nix ({ pkgs, ... }:
+{
+  name = "vault";
+  meta = with pkgs.stdenv.lib.maintainers; {
+    maintainers = [ lnl7 ];
+  };
+  machine = { config, pkgs, ... }: {
+    environment.systemPackages = [ pkgs.vault ];
+    environment.variables.VAULT_ADDR = "http://127.0.0.1:8200";
+    services.vault.enable = true;
+  };
+
+  testScript =
+    ''
+      startAll;
+
+      $machine->waitForUnit('multi-user.target');
+      $machine->waitForUnit('vault.service');
+      $machine->waitForOpenPort(8200);
+      $machine->succeed('vault init');
+      $machine->succeed('vault status | grep "Sealed: true"');
+    '';
+})