This should help identify cases where the Gradle build only works if
it runs before or after a Maven build. It will also help us recognize
any Maven regressions accidentally introduced by our Gradle work.
Eventually I'll want to swap that order, so that we know that Gradle
builds work even without any help from Maven build setup logic. For
now, though, I just want to test whether the Gradle build works at
all.
Using the `xvfb-run` script gives us automatic lifetime management for
the virtual X server: it will start before the `mvn` test script and
will terminate when that test script exits. The `xvfb-run` script
also sets `$DISPLAY` properly in the `mvn` test script, so we no
longer need to manage that setting ourselves.
This should make it easier for newcomers to get WALA up and running
from sources. One no longer needs to manually find "dx.jar" using
instructions given at
<http://wala.sourceforge.net/wiki/index.php/UserGuide:Getting_Started#Building_the_code>
or
<https://groups.google.com/forum/#!msg/wala-sourceforge-net/cBYsfEvYVG0/Ua52dyQQU-YJ>.
Those instructions were already out-of-date, anyway.
Given that an official release of "dx.jar" is available in Maven, it
would be nice to have Maven itself manage that dependency.
Unfortunately, it seems that WALA in general does not use Maven for
dependency management. As far as I can tell, the Maven configuration
just calls out to Ant for doing builds, including having Ant download
other needed components. If WALA ever moved to using Maven more
fully, downloading "dx.jar" could easily come along with that.