The PDO_OCI tests augment the generic PDO tests.
To run the PDO tests for PDO_OCI, execute commands similar to:
export PDO_TEST_DIR=/wherever/php-src/ext/pdo/tests/
export PDO_OCI_TEST_DIR=/wherever/pecl-database-pdo_oci/tests/
export PDO_OCI_TEST_DSN='oci:dbname=localhost/freepdb1;charset=AL32UTF8'
export PDO_OCI_TEST_USER=system
export PDO_OCI_TEST_PASS=oracle
cd /wherever/pecl-database-pdo_oci
php /wherever/php-src/run-tests.php --set-timeout 600 ./tests