nixos/tests: add systemd-analyze test

nixos/tests/all-tests.nix

@@ -258,6 +258,7 @@ in
   syncthing-init = handleTest ./syncthing-init.nix {};
   syncthing-relay = handleTest ./syncthing-relay.nix {};
   systemd = handleTest ./systemd.nix {};
+  systemd-analyze = handleTest ./systemd-analyze.nix {};
   systemd-confinement = handleTest ./systemd-confinement.nix {};
   systemd-timesyncd = handleTest ./systemd-timesyncd.nix {};
   systemd-networkd-wireguard = handleTest ./systemd-networkd-wireguard.nix {};

nixos/tests/systemd-analyze.nix

@@ -0,0 +1,46 @@
+import ./make-test-python.nix ({ pkgs, latestKernel ? false, ... }:
+
+{
+  name = "systemd-analyze";
+  meta = with pkgs.stdenv.lib.maintainers; {
+    maintainers = [ raskin ];
+  };
+
+  machine =
+    { pkgs, lib, ... }:
+    { boot.kernelPackages = lib.mkIf latestKernel pkgs.linuxPackages_latest;
+      sound.enable = true; # needed for the factl test, /dev/snd/* exists without them but udev doesn't care then
+    };
+
+  testScript = ''
+    machine.wait_for_unit("multi-user.target")
+
+    # We create a special output directory to copy it as a whole
+    with subtest("Prepare output dir"):
+        machine.succeed("mkdir systemd-analyze")
+
+
+    # Save the output into a file with given name inside the common
+    # output directory
+    def run_systemd_analyze(args, name):
+        tgt_dir = "systemd-analyze"
+        machine.succeed(
+            "systemd-analyze {} > {}/{} 2> {}/{}.err".format(
+                " ".join(args), tgt_dir, name, tgt_dir, name
+            )
+        )
+
+
+    with subtest("Print statistics"):
+        run_systemd_analyze(["blame"], "blame.txt")
+        run_systemd_analyze(["critical-chain"], "critical-chain.txt")
+        run_systemd_analyze(["dot"], "dependencies.dot")
+        run_systemd_analyze(["plot"], "systemd-analyze.svg")
+
+    # We copy the main graph into the $out (toplevel), and we also copy
+    # the entire output directory with additional data
+    with subtest("Copying the resulting data into $out"):
+        machine.copy_from_vm("systemd-analyze/", "")
+        machine.copy_from_vm("systemd-analyze/systemd-analyze.svg", "")
+  '';
+})