Bugfix: with one ws per output, don’t crash on cross-output moves (Thanks moju)

fixes #827

testcases/t/507-workspace-move-crash.t

@@ -0,0 +1,48 @@
+#!perl
+# vim:ts=4:sw=4:expandtab
+#
+# Please read the following documents before working on tests:
+# • http://build.i3wm.org/docs/testsuite.html
+#   (or docs/testsuite)
+#
+# • http://build.i3wm.org/docs/lib-i3test.html
+#   (alternatively: perldoc ./testcases/lib/i3test.pm)
+#
+# • http://build.i3wm.org/docs/ipc.html
+#   (or docs/ipc)
+#
+# • http://onyxneon.com/books/modern_perl/modern_perl_a4.pdf
+#   (unless you are already familiar with Perl)
+#
+# Tests whether i3 crashes on cross-output moves with one workspace per output.
+# Ticket: #827
+# Bug still in: 4.3-78-g66b389c
+#
+use List::Util qw(first);
+use i3test i3_autostart => 0;
+
+# Ensure the pointer is at (0, 0) so that we really start on the first
+# (the left) workspace.
+$x->root->warp_pointer(0, 0);
+
+my $config = <<EOT;
+# i3 config file (v4)
+font -misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1
+
+fake-outputs 1024x768+0+0,1024x768+1024+0
+EOT
+my $pid = launch_with_config($config);
+
+################################################################################
+# Setup workspaces so that they stay open (with an empty container).
+################################################################################
+
+is(focused_ws, '1', 'starting on workspace 1');
+
+cmd 'move workspace to output fake-1';
+
+does_i3_live;
+
+exit_gracefully($pid);
+
+done_testing;