skip tests for uninstalled extensions

tests/Doctrine/Tests/DBAL/Driver/IBMDB2/DB2ConnectionTest.php

@@ -15,6 +15,10 @@ class DB2ConnectionTest extends DbalTestCase
 
     protected function setUp()
     {
+        if ( ! extension_loaded('ibm_db2')) {
+            $this->markTestSkipped('ibm_db2 is not installed.');
+        }
+
         parent::setUp();
 
         $this->connectionMock = $this->getMockBuilder('Doctrine\DBAL\Driver\IBMDB2\DB2Connection')

tests/Doctrine/Tests/DBAL/Driver/Mysqli/MysqliConnectionTest.php

@@ -15,6 +15,10 @@ class MysqliConnectionTest extends DbalTestCase
 
     protected function setUp()
     {
+        if ( ! extension_loaded('mysqli')) {
+            $this->markTestSkipped('mysqli is not installed.');
+        }
+
         parent::setUp();
 
         $this->connectionMock = $this->getMockBuilder('Doctrine\DBAL\Driver\Mysqli\MysqliConnection')

tests/Doctrine/Tests/DBAL/Driver/OCI8/OCI8ConnectionTest.php

@@ -15,6 +15,10 @@ class OCI8ConnectionTest extends DbalTestCase
 
     protected function setUp()
     {
+        if ( ! extension_loaded('oci8')) {
+            $this->markTestSkipped('oci8 is not installed.');
+        }
+
         parent::setUp();
 
         $this->connectionMock = $this->getMockBuilder('Doctrine\DBAL\Driver\OCI8\OCI8Connection')

tests/Doctrine/Tests/DBAL/Driver/PDOExceptionTest.php

@@ -29,6 +29,10 @@ class PDOExceptionTest extends DbalTestCase
 
     protected function setUp()
     {
+        if ( ! extension_loaded('PDO')) {
+            $this->markTestSkipped('PDO is not installed.');
+        }
+
         parent::setUp();
 
         $this->wrappedExceptionMock = $this->getMockBuilder('\PDOException')

tests/Doctrine/Tests/DBAL/Driver/SQLAnywhere/SQLAnywhereConnectionTest.php

@@ -15,6 +15,10 @@ class SQLAnywhereConnectionTest extends DbalTestCase
 
     protected function setUp()
     {
+        if ( ! extension_loaded('sqlanywhere')) {
+            $this->markTestSkipped('sqlanywhere is not installed.');
+        }
+
         parent::setUp();
 
         $this->connectionMock = $this->getMockBuilder('Doctrine\DBAL\Driver\SQLAnywhere\SQLAnywhereConnection')

tests/Doctrine/Tests/DBAL/Driver/SQLSrv/SQLSrvConnectionTest.php

@@ -15,6 +15,10 @@ class SQLSrvConnectionTest extends DbalTestCase
 
     protected function setUp()
     {
+        if ( ! extension_loaded('sqlsrv')) {
+            $this->markTestSkipped('sqlsrv is not installed.');
+        }
+
         parent::setUp();
 
         $this->connectionMock = $this->getMockBuilder('Doctrine\DBAL\Driver\SQLSrv\SQLSrvConnection')