add a testcase for the shmlog command

testcases/t/207-shmlog.t

@@ -0,0 +1,87 @@
+#!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)
+#
+use i3test i3_autostart => 0;
+use IPC::Run qw(run);
+use File::Temp;
+
+################################################################################
+# 1: test that shared memory logging does not work yet
+################################################################################
+
+my $config = <<EOT;
+# i3 config file (v4)
+font -misc-fixed-medium-r-normal--13-120-75-75-C-70-iso10646-1
+EOT
+
+# NB: launch_with_config sets --shmlog-size=0 because the logfile gets
+# redirected via stdout redirection anyways.
+my $pid = launch_with_config($config);
+
+my $stdout;
+my $stderr;
+run [ '../i3-dump-log/i3-dump-log' ],
+    '>', \$stdout,
+    '2>', \$stderr;
+
+like($stderr, qr#^i3-dump-log: ERROR: i3 is running, but SHM logging is not enabled\.#,
+    'shm logging not enabled');
+
+################################################################################
+# 2: enable shared memory logging and verify new content shows up
+################################################################################
+
+cmd 'shmlog on';
+
+my $random_nop = mktemp('nop.XXXXXX');
+cmd "nop $random_nop";
+
+run [ '../i3-dump-log/i3-dump-log' ],
+    '>', \$stdout,
+    '2>', \$stderr;
+
+like($stdout, qr#$random_nop#, 'random nop found in shm log');
+like($stderr, qr#^$#, 'stderr empty');
+
+################################################################################
+# 3: change size of the shared memory log buffer and verify old content is gone
+################################################################################
+
+cmd 'shmlog ' . (23 * 1024 * 1024);
+
+run [ '../i3-dump-log/i3-dump-log' ],
+    '>', \$stdout,
+    '2>', \$stderr;
+
+unlike($stdout, qr#$random_nop#, 'random nop not found in shm log');
+like($stderr, qr#^$#, 'stderr empty');
+
+################################################################################
+# 4: disable logging and verify it no longer works
+################################################################################
+
+cmd 'shmlog off';
+
+run [ '../i3-dump-log/i3-dump-log' ],
+    '>', \$stdout,
+    '2>', \$stderr;
+
+like($stderr, qr#^i3-dump-log: ERROR: i3 is running, but SHM logging is not enabled\.#,
+    'shm logging not enabled');
+
+exit_gracefully($pid);
+
+done_testing;