This command is a thin wrapper around the test method in
Dist::Zilla. It builds your dist and runs the tests with the AUTHOR_TESTING
environment variable turned on, so its like doing this:
dzil build --no-tgz
A build that fails tests will be left behind for analysis, and dzil will
exit a non-zero value. If the tests are successful, the build directory will
be removed and dzil will exit with status 0.