nixos/tests/chromium: Run tests as normal user

The tests have failed because Chromium has started up displaying the
following error message in a dialog window:

Chromium can not be run as root.

Please start Chromium as a normal user. If you need to run as root for
development, rerun with the --no-sandbox flag.

So let's run as user "alice" and pass all commands using the small
helper function "ru" (to keep it short, it's for "Run as User").

Tested it by running the "stable" test on x86_64-linux.

Signed-off-by: aszlig <[e-mail]>
Reported-by: @globin

nixos/tests/chromium.nix

···
 
   enableOCR = true;
 
-  machine.imports = [ ./common/x11.nix ];
+  machine.imports = [ ./common/user-account.nix ./common/x11.nix ];
   machine.virtualisation.memorySize = 2047;
+  machine.services.xserver.displayManager.auto.user = "alice";
   machine.environment.systemPackages = [ chromiumPkg ];
 
   startupHTML = pkgs.writeText "chromium-startup.html" ''
···
       xdoScript = pkgs.writeText "${name}.xdo" text;
     in "${pkgs.xdotool}/bin/xdotool '${xdoScript}'";
   in ''
+    # Run as user alice
+    sub ru ($) {
+      my $esc = $_[0] =~ s/'/'\\${"'"}'/gr;
+      return "su - alice -c '$esc'";
+    }
+
     sub createNewWin {
       $machine->nest("creating a new Chromium window", sub {
-        $machine->execute("${xdo "new-window" ''
+        $machine->execute(ru "${xdo "new-window" ''
           search --onlyvisible --name "startup done"
           windowfocus --sync
           windowactivate --sync
         ''}");
-        $machine->execute("${xdo "new-window" ''
+        $machine->execute(ru "${xdo "new-window" ''
           key Ctrl+n
         ''}");
       });
···
 
     sub closeWin {
       Machine::retry sub {
-        $machine->execute("${xdo "close-window" ''
+        $machine->execute(ru "${xdo "close-window" ''
           search --onlyvisible --name "new tab"
           windowfocus --sync
           windowactivate --sync
         ''}");
-        $machine->execute("${xdo "close-window" ''
+        $machine->execute(ru "${xdo "close-window" ''
           key Ctrl+w
         ''}");
         for (1..20) {
-          my ($status, $out) = $machine->execute("${xdo "wait-for-close" ''
+          my ($status, $out) = $machine->execute(ru "${xdo "wait-for-close" ''
             search --onlyvisible --name "new tab"
           ''}");
           return 1 if $status != 0;
···
       my $ret = 0;
       $machine->nest("waiting for new Chromium window to appear", sub {
         for (1..20) {
-          my ($status, $out) = $machine->execute("${xdo "wait-for-window" ''
+          my ($status, $out) = $machine->execute(ru "${xdo "wait-for-window" ''
             search --onlyvisible --name "new tab"
             windowfocus --sync
             windowactivate --sync
···
     $machine->waitForX;
 
     my $url = "file://${startupHTML}";
-    my $args = "--user-data-dir=/tmp/chromium-${channel}";
-    $machine->execute(
-      "ulimit -c unlimited; ".
-      "chromium $args \"$url\" & disown"
-    );
+    $machine->execute(ru "ulimit -c unlimited; chromium \"$url\" & disown");
     $machine->waitForText(qr/startup done/);
-    $machine->waitUntilSucceeds("${xdo "check-startup" ''
+    $machine->waitUntilSucceeds(ru "${xdo "check-startup" ''
       search --sync --onlyvisible --name "startup done"
       # close first start help popup
       key -delay 1000 Escape
···
     $machine->screenshot("startup_done");
 
     testNewWin "check sandbox", sub {
-      $machine->succeed("${xdo "type-url" ''
+      $machine->succeed(ru "${xdo "type-url" ''
         search --sync --onlyvisible --name "new tab"
         windowfocus --sync
         type --delay 1000 "chrome://sandbox"
       ''}");
 
-      $machine->succeed("${xdo "submit-url" ''
+      $machine->succeed(ru "${xdo "submit-url" ''
         search --sync --onlyvisible --name "new tab"
         windowfocus --sync
         key --delay 1000 Return
···
 
       $machine->screenshot("sandbox_info");
 
-      $machine->succeed("${xdo "submit-url" ''
+      $machine->succeed(ru "${xdo "submit-url" ''
         search --sync --onlyvisible --name "sandbox status"
         windowfocus --sync
       ''}");
-      $machine->succeed("${xdo "submit-url" ''
+      $machine->succeed(ru "${xdo "submit-url" ''
         key --delay 1000 Ctrl+a Ctrl+c
       ''}");
 
-      my $clipboard = $machine->succeed("${pkgs.xclip}/bin/xclip -o");
+      my $clipboard = $machine->succeed(ru "${pkgs.xclip}/bin/xclip -o");
       die "sandbox not working properly: $clipboard"
       unless $clipboard =~ /namespace sandbox.*yes/mi
           && $clipboard =~ /pid namespaces.*yes/mi