Add testcase for checking if the focus stack is correct when mapping/unmapping floating clients

testcases/t/08-focus-stack.t

@@ -0,0 +1,64 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+# Checks if the focus is correctly restored, when creating a floating client
+# over an unfocused tiling client and destroying the floating one again.
+
+use Test::More tests => 5;
+use Test::Deep;
+use X11::XCB qw(:all);
+use Data::Dumper;
+use Time::HiRes qw(sleep);
+use FindBin;
+use lib "$FindBin::Bin/lib";
+use i3test;
+
+BEGIN {
+    use_ok('IO::Socket::UNIX') or BAIL_OUT('Cannot load IO::Socket::UNIX');
+    use_ok('X11::XCB::Window') or BAIL_OUT('Could not load X11::XCB::Window');
+}
+
+X11::XCB::Connection->connect(':0');
+
+my $sock = IO::Socket::UNIX->new(Peer => '/tmp/i3-ipc.sock');
+isa_ok($sock, 'IO::Socket::UNIX');
+
+# Switch to the nineth workspace
+$sock->write(i3test::format_ipc_command("9"));
+
+sleep(0.25);
+
+
+my $tiled_left = i3test::open_standard_window;
+my $tiled_right = i3test::open_standard_window;
+
+sleep(0.25);
+
+$sock->write(i3test::format_ipc_command("ml"));
+
+# Get input focus before creating the floating window
+my $focus = X11::XCB::Connection->input_focus;
+
+# Create a floating window which is smaller than the minimum enforced size of i3
+my $original_rect = X11::XCB::Rect->new(x => 1, y => 1, width => 30, height => 30);
+
+my $window = X11::XCB::Window->new(
+    class => WINDOW_CLASS_INPUT_OUTPUT,
+    rect => $original_rect,
+    background_color => 12632256,
+    type => 'utility',
+);
+
+isa_ok($window, 'X11::XCB::Window');
+
+$window->create;
+$window->map;
+
+sleep(0.25);
+
+$window->unmap;
+
+sleep(0.25);
+
+is(X11::XCB::Connection->input_focus, $focus, 'Focus correctly restored');
+
+diag( "Testing i3, Perl $], $^X" );