Nuno Lopes has been putting much needed work into PHP code coverage, adding new tests and working on the test system.
A week or so ago he enabled oci8 tests on PHP's Test and Code Coverage Analysis system. The PHP 5.2 Code Coverage numbers are in good shape for the oci8 extension. The work done on re-factoring the extension and its subsequent maintenance mostly by Antony Dovgal is commendable.
On the 2006-12-19 run, oci8 extension code coverage was ahead of the other DB drivers listed.