diff --git a/nixos/tests/virtualbox.nix b/nixos/tests/virtualbox.nix
index d07272360dde..45d31b6f2ab0 100644
--- a/nixos/tests/virtualbox.nix
+++ b/nixos/tests/virtualbox.nix
@@ -15,7 +15,7 @@
 
 assert use64bitGuest -> useKvmNestedVirt;
 
-with import ../lib/testing.nix { inherit system pkgs; };
+with import ../lib/testing-python.nix { inherit system pkgs; };
 with pkgs.lib;
 
 let
@@ -99,7 +99,7 @@ let
     rotated = map (i: "${logfile}.${toString i}") (range 1 9);
     all = concatMapStringsSep " " (f: "\"${f}\"") ([logfile] ++ rotated);
     logcmd = "tail -F ${all} 2> /dev/null | logger -t \"${tag}\"";
-  in optionalString debug "$machine->execute(ru '${logcmd} & disown');";
+  in if debug then "machine.execute(ru('${logcmd} & disown'))" else "pass";
 
   testVM = vmName: vmScript: let
     cfg = (import ../lib/eval-config.nix {
@@ -207,96 +207,105 @@ let
     };
 
     testSubs = ''
-      my ${"$" + name}_sharepath = '${sharePath}';
 
-      sub checkRunning_${name} {
-        my $cmd = 'VBoxManage list runningvms | grep -q "^\"${name}\""';
-        my ($status, $out) = $machine->execute(ru $cmd);
-        return $status == 0;
-      }
 
-      sub cleanup_${name} {
-        $machine->execute(ru "VBoxManage controlvm ${name} poweroff")
-          if checkRunning_${name};
-        $machine->succeed("rm -rf ${sharePath}");
-        $machine->succeed("mkdir -p ${sharePath}");
-        $machine->succeed("chown alice.users ${sharePath}");
-      }
+      ${name}_sharepath = "${sharePath}"
 
-      sub createVM_${name} {
-        vbm("createvm --name ${name} ${createFlags}");
-        vbm("modifyvm ${name} ${vmFlags}");
-        vbm("setextradata ${name} VBoxInternal/PDM/HaltOnReset 1");
-        vbm("storagectl ${name} ${controllerFlags}");
-        vbm("storageattach ${name} ${diskFlags}");
-        vbm("sharedfolder add ${name} ${sharedFlags}");
-        vbm("sharedfolder add ${name} ${nixstoreFlags}");
-        cleanup_${name};
 
-        ${mkLog "$HOME/VirtualBox VMs/${name}/Logs/VBox.log" "HOST-${name}"}
-      }
+      def check_running_${name}():
+          cmd = "VBoxManage list runningvms | grep -q '^\"${name}\"'"
+          (status, _) = machine.execute(ru(cmd))
+          return status == 0
 
-      sub destroyVM_${name} {
-        cleanup_${name};
-        vbm("unregistervm ${name} --delete");
-      }
 
-      sub waitForVMBoot_${name} {
-        $machine->execute(ru(
-          'set -e; i=0; '.
-          'while ! test -e ${sharePath}/boot-done; do '.
-          'sleep 10; i=$(($i + 10)); [ $i -le 3600 ]; '.
-          'VBoxManage list runningvms | grep -q "^\"${name}\""; '.
-          'done'
-        ));
-      }
+      def cleanup_${name}():
+          if check_running_${name}():
+              machine.execute(ru("VBoxManage controlvm ${name} poweroff"))
+          machine.succeed("rm -rf ${sharePath}")
+          machine.succeed("mkdir -p ${sharePath}")
+          machine.succeed("chown alice.users ${sharePath}")
 
-      sub waitForIP_${name} ($) {
-        my $property = "/VirtualBox/GuestInfo/Net/$_[0]/V4/IP";
-        my $getip = "VBoxManage guestproperty get ${name} $property | ".
-                    "sed -n -e 's/^Value: //p'";
-        my $ip = $machine->succeed(ru(
-          'for i in $(seq 1000); do '.
-          'if ipaddr="$('.$getip.')" && [ -n "$ipaddr" ]; then '.
-          'echo "$ipaddr"; exit 0; '.
-          'fi; '.
-          'sleep 1; '.
-          'done; '.
-          'echo "Could not get IPv4 address for ${name}!" >&2; '.
-          'exit 1'
-        ));
-        chomp $ip;
-        return $ip;
-      }
 
-      sub waitForStartup_${name} {
-        for (my $i = 0; $i <= 120; $i += 10) {
-          $machine->sleep(10);
-          return if checkRunning_${name};
-          eval { $_[0]->() } if defined $_[0];
-        }
-        die "VirtualBox VM didn't start up within 2 minutes";
-      }
+      def create_vm_${name}():
+          # fmt: off
+          vbm(f"createvm --name ${name} ${createFlags}")
+          vbm(f"modifyvm ${name} ${vmFlags}")
+          vbm(f"setextradata ${name} VBoxInternal/PDM/HaltOnReset 1")
+          vbm(f"storagectl ${name} ${controllerFlags}")
+          vbm(f"storageattach ${name} ${diskFlags}")
+          vbm(f"sharedfolder add ${name} ${sharedFlags}")
+          vbm(f"sharedfolder add ${name} ${nixstoreFlags}")
+          cleanup_${name}()
 
-      sub waitForShutdown_${name} {
-        for (my $i = 0; $i <= 120; $i += 10) {
-          $machine->sleep(10);
-          return unless checkRunning_${name};
-        }
-        die "VirtualBox VM didn't shut down within 2 minutes";
-      }
+          ${mkLog "$HOME/VirtualBox VMs/${name}/Logs/VBox.log" "HOST-${name}"}
+          # fmt: on
 
-      sub shutdownVM_${name} {
-        $machine->succeed(ru "touch ${sharePath}/shutdown");
-        $machine->execute(
-          'set -e; i=0; '.
-          'while test -e ${sharePath}/shutdown '.
-          '        -o -e ${sharePath}/boot-done; do '.
-          'sleep 1; i=$(($i + 1)); [ $i -le 3600 ]; '.
-          'done'
-        );
-        waitForShutdown_${name};
-      }
+
+      def destroy_vm_${name}():
+          cleanup_${name}()
+          vbm("unregistervm ${name} --delete")
+
+
+      def wait_for_vm_boot_${name}():
+          machine.execute(
+              ru(
+                  "set -e; i=0; "
+                  "while ! test -e ${sharePath}/boot-done; do "
+                  "sleep 10; i=$(($i + 10)); [ $i -le 3600 ]; "
+                  "VBoxManage list runningvms | grep -q '^\"${name}\"'; "
+                  "done"
+              )
+          )
+
+
+      def wait_for_ip_${name}(interface):
+          property = f"/VirtualBox/GuestInfo/Net/{interface}/V4/IP"
+          # fmt: off
+          getip = f"VBoxManage guestproperty get ${name} {property} | sed -n -e 's/^Value: //p'"
+          # fmt: on
+
+          ip = machine.succeed(
+              ru(
+                  "for i in $(seq 1000); do "
+                  f'if ipaddr="$({getip})" && [ -n "$ipaddr" ]; then '
+                  'echo "$ipaddr"; exit 0; '
+                  "fi; "
+                  "sleep 1; "
+                  "done; "
+                  "echo 'Could not get IPv4 address for ${name}!' >&2; "
+                  "exit 1"
+              )
+          ).strip()
+          return ip
+
+
+      def wait_for_startup_${name}(nudge=lambda: None):
+          for _ in range(0, 130, 10):
+              machine.sleep(10)
+              if check_running_${name}():
+                  return
+              nudge()
+          raise Exception("VirtualBox VM didn't start up within 2 minutes")
+
+
+      def wait_for_shutdown_${name}():
+          for _ in range(0, 130, 10):
+              machine.sleep(10)
+              if not check_running_${name}():
+                  return
+          raise Exception("VirtualBox VM didn't shut down within 2 minutes")
+
+
+      def shutdown_vm_${name}():
+          machine.succeed(ru("touch ${sharePath}/shutdown"))
+          machine.execute(
+              "set -e; i=0; "
+              "while test -e ${sharePath}/shutdown "
+              "        -o -e ${sharePath}/boot-done; do "
+              "sleep 1; i=$(($i + 1)); [ $i -le 3600 ]; "
+              "done"
+          )
+          wait_for_shutdown_${name}()
     '';
   };
 
@@ -367,26 +376,31 @@ let
     };
 
     testScript = ''
-      sub ru ($) {
-        my $esc = $_[0] =~ s/'/'\\${"'"}'/gr;
-        return "su - alice -c '$esc'";
-      }
-
-      sub vbm {
-        $machine->succeed(ru("VBoxManage ".$_[0]));
-      };
-
-      sub removeUUIDs {
-        return join("\n", grep { $_ !~ /^UUID:/ } split(/\n/, $_[0]))."\n";
-      }
-
+      from shlex import quote
       ${concatStrings (mapAttrsToList (_: getAttr "testSubs") vms)}
 
-      $machine->waitForX;
+      def ru(cmd: str) -> str:
+          return f"su - alice -c {quote(cmd)}"
 
+
+      def vbm(cmd: str) -> str:
+          return machine.succeed(ru(f"VBoxManage {cmd}"))
+
+
+      def remove_uuids(output: str) -> str:
+          return "\n".join(
+              [line for line in (output or "").splitlines() if not line.startswith("UUID:")]
+          )
+
+
+      machine.wait_for_x()
+
+      # fmt: off
       ${mkLog "$HOME/.config/VirtualBox/VBoxSVC.log" "HOST-SVC"}
+      # fmt: on
 
       ${testScript}
+      # (keep black happy)
     '';
 
     meta = with pkgs.stdenv.lib.maintainers; {
@@ -396,133 +410,129 @@ let
 
   unfreeTests = mapAttrs (mkVBoxTest true vboxVMsWithExtpack) {
     enable-extension-pack = ''
-      createVM_testExtensionPack;
-      vbm("startvm testExtensionPack");
-      waitForStartup_testExtensionPack;
-      $machine->screenshot("cli_started");
-      waitForVMBoot_testExtensionPack;
-      $machine->screenshot("cli_booted");
+      create_vm_testExtensionPack()
+      vbm("startvm testExtensionPack")
+      wait_for_startup_testExtensionPack()
+      machine.screenshot("cli_started")
+      wait_for_vm_boot_testExtensionPack()
+      machine.screenshot("cli_booted")
 
-      $machine->nest("Checking for privilege escalation", sub {
-        $machine->fail("test -e '/root/VirtualBox VMs'");
-        $machine->fail("test -e '/root/.config/VirtualBox'");
-        $machine->succeed("test -e '/home/alice/VirtualBox VMs'");
-      });
+      with machine.nested("Checking for privilege escalation"):
+          machine.fail("test -e '/root/VirtualBox VMs'")
+          machine.fail("test -e '/root/.config/VirtualBox'")
+          machine.succeed("test -e '/home/alice/VirtualBox VMs'")
 
-      shutdownVM_testExtensionPack;
-      destroyVM_testExtensionPack;
+      shutdown_vm_testExtensionPack()
+      destroy_vm_testExtensionPack()
     '';
   };
 
 in mapAttrs (mkVBoxTest false vboxVMs) {
   simple-gui = ''
-    createVM_simple;
-    $machine->succeed(ru "VirtualBox &");
-    $machine->waitUntilSucceeds(
-      ru "xprop -name 'Oracle VM VirtualBox Manager'"
-    );
-    $machine->sleep(5);
-    $machine->screenshot("gui_manager_started");
     # Home to select Tools, down to move to the VM, enter to start it.
-    $machine->sendKeys("home");
-    $machine->sendKeys("down");
-    $machine->sendKeys("ret");
-    $machine->screenshot("gui_manager_sent_startup");
-    waitForStartup_simple (sub {
-      $machine->sendKeys("home");
-      $machine->sendKeys("down");
-      $machine->sendKeys("ret");
-    });
-    $machine->screenshot("gui_started");
-    waitForVMBoot_simple;
-    $machine->screenshot("gui_booted");
-    shutdownVM_simple;
-    $machine->sleep(5);
-    $machine->screenshot("gui_stopped");
-    $machine->sendKeys("ctrl-q");
-    $machine->sleep(5);
-    $machine->screenshot("gui_manager_stopped");
-    destroyVM_simple;
+    def send_vm_startup():
+        machine.send_key("home")
+        machine.send_key("down")
+        machine.send_key("ret")
+
+
+    create_vm_simple()
+    machine.succeed(ru("VirtualBox &"))
+    machine.wait_until_succeeds(ru("xprop -name 'Oracle VM VirtualBox Manager'"))
+    machine.sleep(5)
+    machine.screenshot("gui_manager_started")
+    send_vm_startup()
+    machine.screenshot("gui_manager_sent_startup")
+    wait_for_startup_simple(send_vm_startup)
+    machine.screenshot("gui_started")
+    wait_for_vm_boot_simple()
+    machine.screenshot("gui_booted")
+    shutdown_vm_simple()
+    machine.sleep(5)
+    machine.screenshot("gui_stopped")
+    machine.send_key("ctrl-q")
+    machine.sleep(5)
+    machine.screenshot("gui_manager_stopped")
+    destroy_vm_simple()
   '';
 
   simple-cli = ''
-    createVM_simple;
-    vbm("startvm simple");
-    waitForStartup_simple;
-    $machine->screenshot("cli_started");
-    waitForVMBoot_simple;
-    $machine->screenshot("cli_booted");
+    create_vm_simple()
+    vbm("startvm simple")
+    wait_for_startup_simple()
+    machine.screenshot("cli_started")
+    wait_for_vm_boot_simple()
+    machine.screenshot("cli_booted")
 
-    $machine->nest("Checking for privilege escalation", sub {
-      $machine->fail("test -e '/root/VirtualBox VMs'");
-      $machine->fail("test -e '/root/.config/VirtualBox'");
-      $machine->succeed("test -e '/home/alice/VirtualBox VMs'");
-    });
+    with machine.nested("Checking for privilege escalation"):
+        machine.fail("test -e '/root/VirtualBox VMs'")
+        machine.fail("test -e '/root/.config/VirtualBox'")
+        machine.succeed("test -e '/home/alice/VirtualBox VMs'")
 
-    shutdownVM_simple;
-    destroyVM_simple;
+    shutdown_vm_simple()
+    destroy_vm_simple()
   '';
 
   headless = ''
-    createVM_headless;
-    $machine->succeed(ru("VBoxHeadless --startvm headless & disown %1"));
-    waitForStartup_headless;
-    waitForVMBoot_headless;
-    shutdownVM_headless;
-    destroyVM_headless;
+    create_vm_headless()
+    machine.succeed(ru("VBoxHeadless --startvm headless & disown %1"))
+    wait_for_startup_headless()
+    wait_for_vm_boot_headless()
+    shutdown_vm_headless()
+    destroy_vm_headless()
   '';
 
   host-usb-permissions = ''
-    my $userUSB = removeUUIDs vbm("list usbhost");
-    print STDERR $userUSB;
-    my $rootUSB = removeUUIDs $machine->succeed("VBoxManage list usbhost");
-    print STDERR $rootUSB;
+    user_usb = remove_uuids(vbm("list usbhost"))
+    print(user_usb, file=sys.stderr)
+    root_usb = remove_uuids(machine.succeed("VBoxManage list usbhost"))
+    print(root_usb, file=sys.stderr)
 
-    die "USB host devices differ for root and normal user"
-      if $userUSB ne $rootUSB;
-    die "No USB host devices found" if $userUSB =~ /<none>/;
+    if user_usb != root_usb:
+        raise Exception("USB host devices differ for root and normal user")
+    if "<none>" in user_usb:
+        raise Exception("No USB host devices found")
   '';
 
   systemd-detect-virt = ''
-    createVM_detectvirt;
-    vbm("startvm detectvirt");
-    waitForStartup_detectvirt;
-    waitForVMBoot_detectvirt;
-    shutdownVM_detectvirt;
-    my $result = $machine->succeed("cat '$detectvirt_sharepath/result'");
-    chomp $result;
-    destroyVM_detectvirt;
-    die "systemd-detect-virt returned \"$result\" instead of \"oracle\""
-      if $result ne "oracle";
+    create_vm_detectvirt()
+    vbm("startvm detectvirt")
+    wait_for_startup_detectvirt()
+    wait_for_vm_boot_detectvirt()
+    shutdown_vm_detectvirt()
+    result = machine.succeed(f"cat '{detectvirt_sharepath}/result'").strip()
+    destroy_vm_detectvirt()
+    if result != "oracle":
+        raise Exception(f'systemd-detect-virt returned "{result}" instead of "oracle"')
   '';
 
   net-hostonlyif = ''
-    createVM_test1;
-    createVM_test2;
+    create_vm_test1()
+    create_vm_test2()
 
-    vbm("startvm test1");
-    waitForStartup_test1;
-    waitForVMBoot_test1;
+    vbm("startvm test1")
+    wait_for_startup_test1()
+    wait_for_vm_boot_test1()
 
-    vbm("startvm test2");
-    waitForStartup_test2;
-    waitForVMBoot_test2;
+    vbm("startvm test2")
+    wait_for_startup_test2()
+    wait_for_vm_boot_test2()
 
-    $machine->screenshot("net_booted");
+    machine.screenshot("net_booted")
 
-    my $test1IP = waitForIP_test1 1;
-    my $test2IP = waitForIP_test2 1;
+    test1_ip = wait_for_ip_test1(1)
+    test2_ip = wait_for_ip_test2(1)
 
-    $machine->succeed("echo '$test2IP' | nc -N '$test1IP' 1234");
-    $machine->succeed("echo '$test1IP' | nc -N '$test2IP' 1234");
+    machine.succeed(f"echo '{test2_ip}' | nc -N '{test1_ip}' 1234")
+    machine.succeed(f"echo '{test1_ip}' | nc -N '{test2_ip}' 1234")
 
-    $machine->waitUntilSucceeds("nc -N '$test1IP' 5678 < /dev/null >&2");
-    $machine->waitUntilSucceeds("nc -N '$test2IP' 5678 < /dev/null >&2");
+    machine.wait_until_succeeds(f"nc -N '{test1_ip}' 5678 < /dev/null >&2")
+    machine.wait_until_succeeds(f"nc -N '{test2_ip}' 5678 < /dev/null >&2")
 
-    shutdownVM_test1;
-    shutdownVM_test2;
+    shutdown_vm_test1()
+    shutdown_vm_test2()
 
-    destroyVM_test1;
-    destroyVM_test2;
+    destroy_vm_test1()
+    destroy_vm_test2()
   '';
 } // (if enableUnfree then unfreeTests else {})