The dlog testsuite consists of a bash script and config files, shipped as a
separate rpm file. The script is capable of testing both backends, chosen by
providing proper argument:
- for pipe backend:
$ @bindir@/dlog_test pipe
- for android logger backend:
$ @bindir@/dlog_test logger

The test environment setup is separate for both backends but performed tests
are the same. Pipe backend environment setup looks as follows:
- a proper config file is installed by rpm in @datadir@/dlog-pipe.conf.test.It
stores paths to sockets used by daemon, util and libdlog based apps during tests
which are separate from those used in production mode
- DLOG_CONFIG_PATH envirinment variable is set to point at installed config file
- a dlog daemon is started, it creates pipe sockets in location specified in
config file pointed by DLOG_CONFIG_PATH env variable - /var/lib/dlog-tests/
- testsuite tests are performed, dlogutil, dlogsend and libdlog based test
apps use socket files specified in config file pointed by DLOG_CONFIG_PATH env
variable
- a test summary is printed, showing total, failed and passed tests count
- daemon and all test apps are killed on exit

Android logger testing is a little bit more tricky, since we cannot just run
separate instance of daemon and communicate with it using separate sockets.
It uses a kernel buffer which is system-wide and shared between all applications
that wish to read or write log entries. Since there are multiple applications
running on target and utilizing dlog all the time, it would be hard to
read/write test log entries along with them and be 100% sure that no test log
entries are lost (for example by overwriting them by entries written by other
applications). However, there is a configuration setting called "platform
logging", normally set to 1, which enables or disables writing to all buffers
except apps buffer.

Taking this into account, android logger environment setup works as follows:
- an overlay config file is installed in
@sysconfdir@/dlog.conf.d/99-dlog-logger.disable-platform-logging-for-testsuite.conf.
It contains only one config entry that disables platform logging. It's being
interpreted as a last config file, so we can be sure nothing else overwrites
this setting. The bottleneck of this approach is that since we need to be sure
that all system apps using libdlog will take this setting into account, a reboot
is required after installing testsuite.
- along with an overlay config file, a proper test config file is installed by
rpm in @datadir@/dlog-logger.conf.test. It contains standard settings for
android backend, but it has platform logging ENABLED
- after reboot, all buffer except apps buffer are free of any log entries
(platform logging disabled)
- DLOG_CONFIG_PATH envirinment variable is set to point at installed config file
@datadir@/dlog-logger.conf.test. It has platform logging enabled, so all
dlogutil, dlogsend and libdlog based applications run from now on in this
environment will have write access to all buffers.
- testsuite tests are performed, both dlogutil and libdlog test apps use
settings specified in config file pointed by DLOG_CONFIG_PATH env variable
- a test summary is printed, showing total, failed and passed tests count
- since an overlay config file is installed in a standard config files location
and is interpreted on each startup, it's advised to uninstall dlog testsuite
after performing tests. This will remove the file and enable platform logging to
all system applications.

Tests are common for both backends and consist of testing if:
- dlogutil -d quits after printing logs
- -t and -u arguments are parsed properly
- limiting printed log count with -t works as expected
- reading from an unknown buffer returns an error
- ireading from empty buffer returns zero entries
- dlogutil -c empties all buffers
- writing to an empty buffer works as expected
- log level filters work
- "silent" filter works
- writing buffer size with dlogutil -g works as expected
- reading all entries to a single file works
- reading all entries to rotating files works
- all print formats work as expected (regex based matching)
- pid/tid filtering works
- sorting by timestamp works