PDO has a set of "core" tests that all drivers should pass before being
  released.  They're designed to run from the PHP source distribution, so
  running the tests for your driver requires moving things around a bit.
  The suggested procedure is to obtain the latest PHP 5.1 snapshot and
  perform the following step:
 
 
$ cp -r pdo_SKEL /path/to/php-5.1/ext
 
 
  This will allow the test harness to run your tests.  The next thing you
  need to do is create a test that will redirect into the PDO common core tests.
  The convention is to name this file common.phpt; it
  should be placed in the tests subdirectory that was created by
  ext_skel when you created your extension skeleton.
  The content of this file should look something like the following:
 
 
--TEST--
SKEL
--SKIPIF--
<?php # vim:ft=php
if (!extension_loaded('pdo_SKEL')) print 'skip'; ?>
--REDIRECTTEST--
if (false !== getenv('PDO_SKEL_TEST_DSN')) {
# user set them from their shell
   $config['ENV']['PDOTEST_DSN'] = getenv('PDO_SKEL_TEST_DSN');
   $config['ENV']['PDOTEST_USER'] = getenv('PDO_SKEL_TEST_USER');
   $config['ENV']['PDOTEST_PASS'] = getenv('PDO_SKEL_TEST_PASS');
   if (false !== getenv('PDO_SKEL_TEST_ATTR')) {
      $config['ENV']['PDOTEST_ATTR'] = getenv('PDO_SKEL_TEST_ATTR');
   }
   return $config;
}
return array(
   'ENV' => array(
           'PDOTEST_DSN' => 'SKEL:dsn',
           'PDOTEST_USER' => 'username',
           'PDOTEST_PASS' => 'password'
       ),
   'TESTS' => 'ext/pdo/tests'
   );
 
 
$ cd /path/to/php-5.1
$ make TESTS=ext/pdo_SKEL/tests PDO_SKEL_TEST_DSN="skel:dsn" \
 PDO_SKEL_TEST_USER=user PDO_SKEL_TEST_PASS=pass test