Fix Exception converting into a non-BC change.

UPGRADE.md

 # Upgrade to 2.5
 
-A new method was added to `Doctrine\DBAL\Driver` interface that you need to implement
-if your project contains custom drivers.
-
-```php
-/**
- * @param \Exception $exception
- *
- * @return int
- */
-public function convertExceptionCode(\Exception $exception);
-```
-
-The most basic implementation for this method just returns 0:
-
-```php
-/**
- * @param \Exception $exception
- *
- * @return int
- */
-public function convertExceptionCode(\Exception $exception)
-{
-    return 0;
-}
-```
-
-You can see the MySQL, SQLite and PostgreSQL drivers for sample implementations with
-the new feature and take a look at `tests/Doctrine/Tests/DBAL/Functional/ExceptionTest.php`
-for testing this functionality.
+No BC breaks yet.
 
 # Upgrade to 2.4
 

lib/Doctrine/DBAL/DBALException.php

@@ -19,6 +19,8 @@
 
 namespace Doctrine\DBAL;
 
+use Doctrine\DBAL\Driver\ExceptionConverterDriver;
+
 class DBALException extends \Exception
 {
     const ERROR_DUPLICATE_KEY = 1;
@@ -101,7 +103,11 @@ class DBALException extends \Exception
         }
         $msg .= ":\n\n".$driverEx->getMessage();
 
-        return new self($msg, $driver->convertExceptionCode($driverEx), $driverEx);
+        $code = ($driver instanceof ExceptionConverterDriver)
+            ? $driver->convertExceptionCode($driverEx)
+            : 0;
+
+        return new self($msg, $code, $driverEx);
     }
 
     /**

lib/Doctrine/DBAL/Driver.php

@@ -73,7 +73,6 @@ interface Driver
      */
     public function getDatabase(Connection $conn);
 
-
     /**
      * @param \Exception $exception
      *

lib/Doctrine/DBAL/Driver/ExceptionConverterDriver.php

+<?php
+/*
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This software consists of voluntary contributions made by many individuals
+ * and is licensed under the MIT license. For more information, see
+ * <http://www.doctrine-project.org>.
+ */
+
+namespace Doctrine\DBAL\Driver;
+
+use Exception;
+
+/**
+ * Drivers marked as ExceptionConverters can convert to standardized codes.
+ *
+ * @since 2.5
+ */
+interface ExceptionConverterDriver
+{
+    /**
+     * @param \Exception $exception
+     *
+     * @return int
+     */
+    public function convertExceptionCode(Exception $exception);
+}

lib/Doctrine/DBAL/Driver/Mysqli/Driver.php

@@ -22,11 +22,12 @@ namespace Doctrine\DBAL\Driver\Mysqli;
 use Doctrine\DBAL\Driver as DriverInterface;
 use Doctrine\DBAL\Driver\Mysqli\MysqliException;
 use Doctrine\DBAL\DBALException;
+use Doctrine\DBAL\Driver\ExceptionConverterDriver;
 
 /**
  * @author Kim Hemsø Rasmussen <kimhemsoe@gmail.com>
  */
-class Driver implements DriverInterface
+class Driver implements DriverInterface, ExceptionConverterDriver
 {
     /**
      * {@inheritdoc}

lib/Doctrine/DBAL/Driver/PDOMySql/Driver.php

@@ -21,6 +21,7 @@ namespace Doctrine\DBAL\Driver\PDOMySql;
 
 use Doctrine\DBAL\Connection;
 use Doctrine\DBAL\DBALException;
+use Doctrine\DBAL\Driver\ExceptionConverterDriver;
 use PDOException;
 
 /**
@@ -28,7 +29,7 @@ use PDOException;
  *
  * @since 2.0
  */
-class Driver implements \Doctrine\DBAL\Driver
+class Driver implements \Doctrine\DBAL\Driver, ExceptionConverterDriver
 {
     /**
      * {@inheritdoc}

lib/Doctrine/DBAL/Driver/PDOPgSql/Driver.php

@@ -22,13 +22,14 @@ namespace Doctrine\DBAL\Driver\PDOPgSql;
 use Doctrine\DBAL\Platforms;
 use Doctrine\DBAL\DBALException;
 use PDOException;
+use Doctrine\DBAL\Driver\ExceptionConverterDriver;
 
 /**
  * Driver that connects through pdo_pgsql.
  *
  * @since 2.0
  */
-class Driver implements \Doctrine\DBAL\Driver
+class Driver implements \Doctrine\DBAL\Driver, ExceptionConverterDriver
 {
     /**
      * {@inheritdoc}

lib/Doctrine/DBAL/Driver/PDOSqlite/Driver.php

@@ -20,6 +20,7 @@
 namespace Doctrine\DBAL\Driver\PDOSqlite;
 
 use Doctrine\DBAL\DBALException;
+use Doctrine\DBAL\Driver\ExceptionConverterDriver;
 use PDOException;
 
 /**
@@ -27,7 +28,7 @@ use PDOException;
  *
  * @since 2.0
  */
-class Driver implements \Doctrine\DBAL\Driver
+class Driver implements \Doctrine\DBAL\Driver, ExceptionConverterDriver
 {
     /**
      * @var array

tests/Doctrine/Tests/DBAL/Functional/ExceptionTest.php

@@ -2,6 +2,7 @@
 namespace Doctrine\Tests\DBAL\Functional;
 
 use Doctrine\DBAL\DBALException;
+use Doctrine\DBAL\Driver\ExceptionConverterDriver;
 
 class ExceptionTest extends \Doctrine\Tests\DbalFunctionalTestCase
 {
@@ -9,10 +10,7 @@ class ExceptionTest extends \Doctrine\Tests\DbalFunctionalTestCase
     {
         parent::setUp();
 
-        $supportExceptions = array('pdo_sqlite', 'pdo_mysql', 'pdo_pgsql', 'mysqli');
-        $params = $this->_conn->getParams();
-
-        if (!in_array($params['driver'], $supportExceptions)) {
+        if ( !($this->_conn->getDriver() instanceof ExceptionConverterDriver)) {
             $this->markTestSkipped('Driver does not support special exception handling.');
         }
     }