+# Prepare a RRGetOutputInfo reply as well; see RRGetOutputInfo in
+# https://www.x.org/releases/current/doc/randrproto/randrproto.txt
+my $output_name = 'i3-fake-output';
+($outfh, my $outname_moninfo) = tempfile('i3-randr15reply-XXXXXX', UNLINK => 1);
+my $moninfo = pack('cxSLLLx[LLccSSSS]S a* x!4',
+ 1, # reply
+ 0, # sequence (will be filled in by inject_randr15)
+ # 36 = length($moninfo) (without name and padding)
+ # 32 = minimum X11 reply length
+ ((36 + length($output_name) - 32) + 3) / 4, # length in words
+ 0, # timestamp TODO
+ 12345, # CRTC
+ length($output_name), # length of name
+ $output_name); # name
+
+print $outfh $moninfo;
+close($outfh);
+
+my $pid = launch_with_config($config,
+ inject_randr15 => $outname,
+ inject_randr15_outputinfo => $outname_moninfo);