diff --git a/apps/user_ldap/user_ldap.php b/apps/user_ldap/user_ldap.php
index 9fa2a6b418c8a920dea050fa95f9b12ed7d2727e..ae4dfec51181f8923936d23c15d40433b100a9ab 100644
--- a/apps/user_ldap/user_ldap.php
+++ b/apps/user_ldap/user_ldap.php
@@ -73,7 +73,6 @@ class USER_LDAP extends BackendUtility implements \OCP\UserInterface {
 			}
 
 			$user->markLogin();
-			$user->update();
 
 			return $user->getUsername();
 		}
diff --git a/lib/private/appconfig.php b/lib/private/appconfig.php
index f20c4a08426d06df32a097960929674003b654c6..1874d9f2b1937358579d622a16875dd68b5f384e 100644
--- a/lib/private/appconfig.php
+++ b/lib/private/appconfig.php
@@ -183,6 +183,10 @@ class AppConfig implements \OCP\IAppConfig {
 			);
 			$this->conn->insert('*PREFIX*appconfig', $data);
 		} else {
+			$oldValue = $this->getValue($app, $key);
+			if($oldValue === strval($value)) {
+				return true;
+			}
 			$data = array(
 				'configvalue' => $value,
 			);
diff --git a/lib/private/preferences.php b/lib/private/preferences.php
index d1db25bbf09c8be74b4cd7692d62b45e50df19d2..a849cc23e1a695c3af76f6b3bacb4c2f3a0408d9 100644
--- a/lib/private/preferences.php
+++ b/lib/private/preferences.php
@@ -173,11 +173,16 @@ class Preferences {
 	 */
 	public function setValue($user, $app, $key, $value, $preCondition = null) {
 		// Check if the key does exist
-		$query = 'SELECT COUNT(*) FROM `*PREFIX*preferences`'
+		$query = 'SELECT `configvalue` FROM `*PREFIX*preferences`'
 			. ' WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?';
-		$count = $this->conn->fetchColumn($query, array($user, $app, $key));
-		$exists = $count > 0;
+		$oldValue = $this->conn->fetchColumn($query, array($user, $app, $key));
+		$exists = $oldValue !== false;
 
+		if($oldValue === strval($value)) {
+			// no changes
+			return true;
+		}
+		
 		$affectedRows = 0;
 
 		if (!$exists && $preCondition === null) {
diff --git a/tests/lib/appconfig.php b/tests/lib/appconfig.php
index 6ae790a9edd774102a40faf8e674823d8de607bc..9257ae45b0ebe307e891392b436dbbb288a4d163 100644
--- a/tests/lib/appconfig.php
+++ b/tests/lib/appconfig.php
@@ -95,6 +95,72 @@ class Test_Appconfig extends PHPUnit_Framework_TestCase {
 		$this->assertEquals('somevalue', $value['configvalue']);
 	}
 
+	public function testSetValueUnchanged() {
+		$statementMock = $this->getMock('\Doctrine\DBAL\Statement', array(), array(), '', false);
+		$statementMock->expects($this->once())
+			->method('fetch')
+			->will($this->returnValue(false));
+
+		$connectionMock = $this->getMock('\OC\DB\Connection', array(), array(), '', false);
+		$connectionMock->expects($this->once())
+			->method('executeQuery')
+			->with($this->equalTo('SELECT `configvalue`, `configkey` FROM `*PREFIX*appconfig`'
+				.' WHERE `appid` = ?'), $this->equalTo(array('bar')))
+			->will($this->returnValue($statementMock));
+		$connectionMock->expects($this->once())
+			->method('insert')
+			->with($this->equalTo('*PREFIX*appconfig'),
+				$this->equalTo(
+					array(
+						'appid' => 'bar',
+						'configkey' => 'foo',
+						'configvalue' => 'v1',
+					)
+				));
+		$connectionMock->expects($this->never())
+			->method('update');
+
+		$appconfig = new OC\AppConfig($connectionMock);
+		$appconfig->setValue('bar', 'foo', 'v1');
+		$appconfig->setValue('bar', 'foo', 'v1');
+		$appconfig->setValue('bar', 'foo', 'v1');
+	}
+
+	public function testSetValueUnchanged2() {
+		$statementMock = $this->getMock('\Doctrine\DBAL\Statement', array(), array(), '', false);
+		$statementMock->expects($this->once())
+			->method('fetch')
+			->will($this->returnValue(false));
+
+		$connectionMock = $this->getMock('\OC\DB\Connection', array(), array(), '', false);
+		$connectionMock->expects($this->once())
+			->method('executeQuery')
+			->with($this->equalTo('SELECT `configvalue`, `configkey` FROM `*PREFIX*appconfig`'
+				.' WHERE `appid` = ?'), $this->equalTo(array('bar')))
+			->will($this->returnValue($statementMock));
+		$connectionMock->expects($this->once())
+			->method('insert')
+			->with($this->equalTo('*PREFIX*appconfig'),
+				$this->equalTo(
+					array(
+						'appid' => 'bar',
+						'configkey' => 'foo',
+						'configvalue' => 'v1',
+					)
+				));
+		$connectionMock->expects($this->once())
+			->method('update')
+			->with($this->equalTo('*PREFIX*appconfig'),
+				$this->equalTo(array('configvalue' => 'v2')),
+				$this->equalTo(array('appid' => 'bar', 'configkey' => 'foo'))
+				);
+
+		$appconfig = new OC\AppConfig($connectionMock);
+		$appconfig->setValue('bar', 'foo', 'v1');
+		$appconfig->setValue('bar', 'foo', 'v2');
+		$appconfig->setValue('bar', 'foo', 'v2');
+	}
+
 	public function testDeleteKey() {
 		\OC_Appconfig::deleteKey('testapp', 'deletethis');
 		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*appconfig` WHERE `appid` = ? AND `configkey` = ?');
diff --git a/tests/lib/preferences-singleton.php b/tests/lib/preferences-singleton.php
new file mode 100644
index 0000000000000000000000000000000000000000..5204775fc43d9eeef825fe49232cad4fbaf8d19c
--- /dev/null
+++ b/tests/lib/preferences-singleton.php
@@ -0,0 +1,396 @@
+<?php
+/**
+ * Copyright (c) 2013 Christopher Schäpers <christopher@schaepers.it>
+ * Copyright (c) 2013 Bart Visscher <bartv@thisnet.nl>
+ * This file is licensed under the Affero General Public License version 3 or
+ * later.
+ * See the COPYING-README file.
+ */
+
+class Test_Preferences extends PHPUnit_Framework_TestCase {
+	public static function setUpBeforeClass() {
+		$query = \OC_DB::prepare('INSERT INTO `*PREFIX*preferences` VALUES(?, ?, ?, ?)');
+		$query->execute(array("Someuser", "someapp", "somekey", "somevalue"));
+
+		$query->execute(array("Someuser", "getusersapp", "somekey", "somevalue"));
+		$query->execute(array("Anotheruser", "getusersapp", "somekey", "someothervalue"));
+		$query->execute(array("Anuser", "getusersapp", "somekey", "somevalue"));
+
+		$query->execute(array("Someuser", "getappsapp", "somekey", "somevalue"));
+
+		$query->execute(array("Someuser", "getkeysapp", "firstkey", "somevalue"));
+		$query->execute(array("Someuser", "getkeysapp", "anotherkey", "somevalue"));
+		$query->execute(array("Someuser", "getkeysapp", "key-tastic", "somevalue"));
+
+		$query->execute(array("Someuser", "getvalueapp", "key", "a value for a key"));
+
+		$query->execute(array("Deleteuser", "deleteapp", "deletekey", "somevalue"));
+		$query->execute(array("Deleteuser", "deleteapp", "somekey", "somevalue"));
+		$query->execute(array("Deleteuser", "someapp", "somekey", "somevalue"));
+	}
+
+	public static function tearDownAfterClass() {
+		$query = \OC_DB::prepare('DELETE FROM `*PREFIX*preferences` WHERE `userid` = ?');
+		$query->execute(array('Someuser'));
+		$query->execute(array('Anotheruser'));
+		$query->execute(array('Anuser'));
+	}
+
+	public function testGetUsers() {
+		$query = \OC_DB::prepare('SELECT DISTINCT `userid` FROM `*PREFIX*preferences`');
+		$result = $query->execute();
+		$expected = array();
+		while ($row = $result->fetchRow()) {
+			$expected[] = $row['userid'];
+		}
+
+		$this->assertEquals($expected, \OC_Preferences::getUsers());
+	}
+
+	public function testGetApps() {
+		$query = \OC_DB::prepare('SELECT DISTINCT `appid` FROM `*PREFIX*preferences` WHERE `userid` = ?');
+		$result = $query->execute(array('Someuser'));
+		$expected = array();
+		while ($row = $result->fetchRow()) {
+			$expected[] = $row['appid'];
+		}
+
+		$this->assertEquals($expected, \OC_Preferences::getApps('Someuser'));
+	}
+
+	public function testGetKeys() {
+		$query = \OC_DB::prepare('SELECT DISTINCT `configkey` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ?');
+		$result = $query->execute(array('Someuser', 'getkeysapp'));
+		$expected = array();
+		while ($row = $result->fetchRow()) {
+			$expected[] = $row['configkey'];
+		}
+
+		$this->assertEquals($expected, \OC_Preferences::getKeys('Someuser', 'getkeysapp'));
+	}
+
+	public function testGetValue() {
+		$this->assertNull(\OC_Preferences::getValue('nonexistant', 'nonexistant', 'nonexistant'));
+
+		$this->assertEquals('default', \OC_Preferences::getValue('nonexistant', 'nonexistant', 'nonexistant', 'default'));
+
+		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
+		$result = $query->execute(array('Someuser', 'getvalueapp', 'key'));
+		$row = $result->fetchRow();
+		$expected = $row['configvalue'];
+		$this->assertEquals($expected, \OC_Preferences::getValue('Someuser', 'getvalueapp', 'key'));
+	}
+
+	public function testSetValue() {
+		$this->assertTrue(\OC_Preferences::setValue('Someuser', 'setvalueapp', 'newkey', 'newvalue'));
+		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
+		$result = $query->execute(array('Someuser', 'setvalueapp', 'newkey'));
+		$row = $result->fetchRow();
+		$value = $row['configvalue'];
+		$this->assertEquals('newvalue', $value);
+
+		$this->assertTrue(\OC_Preferences::setValue('Someuser', 'setvalueapp', 'newkey', 'othervalue'));
+		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
+		$result = $query->execute(array('Someuser', 'setvalueapp', 'newkey'));
+		$row = $result->fetchRow();
+		$value = $row['configvalue'];
+		$this->assertEquals('othervalue', $value);
+	}
+
+	public function testSetValueWithPreCondition() {
+		// remove existing key
+		$this->assertTrue(\OC_Preferences::deleteKey('Someuser', 'setvalueapp', 'newkey'));
+
+		// add new preference with pre-condition should fails
+		$this->assertFalse(\OC_Preferences::setValue('Someuser', 'setvalueapp', 'newkey', 'newvalue', 'preCondition'));
+		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
+		$result = $query->execute(array('Someuser', 'setvalueapp', 'newkey'));
+		$row = $result->fetchRow();
+		$this->assertFalse($row);
+
+		// add new preference without pre-condition should insert the new value
+		$this->assertTrue(\OC_Preferences::setValue('Someuser', 'setvalueapp', 'newkey', 'newvalue'));
+		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
+		$result = $query->execute(array('Someuser', 'setvalueapp', 'newkey'));
+		$row = $result->fetchRow();
+		$value = $row['configvalue'];
+		$this->assertEquals('newvalue', $value);
+
+		// wrong pre-condition, value should stay the same
+		$this->assertFalse(\OC_Preferences::setValue('Someuser', 'setvalueapp', 'newkey', 'othervalue', 'preCondition'));
+		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
+		$result = $query->execute(array('Someuser', 'setvalueapp', 'newkey'));
+		$row = $result->fetchRow();
+		$value = $row['configvalue'];
+		$this->assertEquals('newvalue', $value);
+
+		// correct pre-condition, value should change
+		$this->assertTrue(\OC_Preferences::setValue('Someuser', 'setvalueapp', 'newkey', 'othervalue', 'newvalue'));
+		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
+		$result = $query->execute(array('Someuser', 'setvalueapp', 'newkey'));
+		$row = $result->fetchRow();
+		$value = $row['configvalue'];
+		$this->assertEquals('othervalue', $value);
+	}
+
+	public function testDeleteKey() {
+		$this->assertTrue(\OC_Preferences::deleteKey('Deleteuser', 'deleteapp', 'deletekey'));
+		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
+		$result = $query->execute(array('Deleteuser', 'deleteapp', 'deletekey'));
+		$this->assertEquals(0, count($result->fetchAll()));
+	}
+
+	public function testDeleteApp() {
+		$this->assertTrue(\OC_Preferences::deleteApp('Deleteuser', 'deleteapp'));
+		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ?');
+		$result = $query->execute(array('Deleteuser', 'deleteapp'));
+		$this->assertEquals(0, count($result->fetchAll()));
+	}
+
+	public function testDeleteUser() {
+		$this->assertTrue(\OC_Preferences::deleteUser('Deleteuser'));
+		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ?');
+		$result = $query->execute(array('Deleteuser'));
+		$this->assertEquals(0, count($result->fetchAll()));
+	}
+
+	public function testDeleteAppFromAllUsers() {
+		$this->assertTrue(\OC_Preferences::deleteAppFromAllUsers('someapp'));
+		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `appid` = ?');
+		$result = $query->execute(array('someapp'));
+		$this->assertEquals(0, count($result->fetchAll()));
+	}
+}
+
+class Test_Preferences_Object extends PHPUnit_Framework_TestCase {
+	public function testGetUsers()
+	{
+		$statementMock = $this->getMock('\Doctrine\DBAL\Statement', array(), array(), '', false);
+		$statementMock->expects($this->exactly(2))
+			->method('fetchColumn')
+			->will($this->onConsecutiveCalls('foo', false));
+		$connectionMock = $this->getMock('\OC\DB\Connection', array(), array(), '', false);
+		$connectionMock->expects($this->once())
+			->method('executeQuery')
+			->with($this->equalTo('SELECT DISTINCT `userid` FROM `*PREFIX*preferences`'))
+			->will($this->returnValue($statementMock));
+
+		$preferences = new OC\Preferences($connectionMock);
+		$apps = $preferences->getUsers();
+		$this->assertEquals(array('foo'), $apps);
+	}
+
+	public function testSetValue()
+	{
+		$connectionMock = $this->getMock('\OC\DB\Connection', array(), array(), '', false);
+		$connectionMock->expects($this->exactly(2))
+			->method('fetchColumn')
+			->with($this->equalTo('SELECT COUNT(*) FROM `*PREFIX*preferences`'
+				.' WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?'),
+				$this->equalTo(array('grg', 'bar', 'foo')))
+			->will($this->onConsecutiveCalls(0, 1));
+		$connectionMock->expects($this->once())
+			->method('insert')
+			->with($this->equalTo('*PREFIX*preferences'),
+				$this->equalTo(
+					array(
+						'userid' => 'grg',
+						'appid' => 'bar',
+						'configkey' => 'foo',
+						'configvalue' => 'v1',
+					)
+				));
+		$connectionMock->expects($this->once())
+			->method('executeUpdate')
+			->with($this->equalTo("UPDATE `*PREFIX*preferences` SET `configvalue` = ?"
+						. " WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?"),
+				$this->equalTo(array('v2', 'grg', 'bar', 'foo'))
+				);
+
+		$preferences = new OC\Preferences($connectionMock);
+		$preferences->setValue('grg', 'bar', 'foo', 'v1');
+		$preferences->setValue('grg', 'bar', 'foo', 'v2');
+	}
+
+	public function testSetValueUnchanged() {
+		$connectionMock = $this->getMock('\OC\DB\Connection', array(), array(), '', false);
+		$connectionMock->expects($this->exactly(2))
+			->method('fetchColumn')
+			->with($this->equalTo('SELECT `configvalue` FROM `*PREFIX*preferences`'
+				.' WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?'),
+				$this->equalTo(array('grg', 'bar', 'foo')))
+			->will($this->onConsecutiveCalls(0, 1));
+		$connectionMock->expects($this->once())
+			->method('insert')
+			->with($this->equalTo('*PREFIX*preferences'),
+				$this->equalTo(
+					array(
+						'userid' => 'grg',
+						'appid' => 'bar',
+						'configkey' => 'foo',
+						'configvalue' => 'v1',
+					)
+				));
+		$connectionMock->expects($this->never())
+			->method('executeUpdate');
+
+		$preferences = new OC\Preferences($connectionMock);
+		$preferences->setValue('grg', 'bar', 'foo', 'v1');
+		$preferences->setValue('grg', 'bar', 'foo', 'v1');
+		$preferences->setValue('grg', 'bar', 'foo', 'v1');
+	}
+
+	public function testSetValueUnchanged2() {
+		$connectionMock = $this->getMock('\OC\DB\Connection', array(), array(), '', false);
+		$connectionMock->expects($this->exactly(2))
+			->method('fetchColumn')
+			->with($this->equalTo('SELECT `configvalue` FROM `*PREFIX*preferences`'
+				.' WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?'),
+				$this->equalTo(array('grg', 'bar', 'foo')))
+			->will($this->onConsecutiveCalls(0, 1));
+		$connectionMock->expects($this->once())
+			->method('insert')
+			->with($this->equalTo('*PREFIX*preferences'),
+				$this->equalTo(
+					array(
+						'userid' => 'grg',
+						'appid' => 'bar',
+						'configkey' => 'foo',
+						'configvalue' => 'v1',
+					)
+				));
+		$connectionMock->expects($this->once())
+			->method('executeUpdate')
+			->with($this->equalTo("UPDATE `*PREFIX*preferences` SET `configvalue` = ?"
+						. " WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?"),
+				$this->equalTo(array('v2', 'grg', 'bar', 'foo'))
+				);
+
+		$preferences = new OC\Preferences($connectionMock);
+		$preferences->setValue('grg', 'bar', 'foo', 'v1');
+		$preferences->setValue('grg', 'bar', 'foo', 'v2');
+		$preferences->setValue('grg', 'bar', 'foo', 'v2');
+	}
+
+	public function testGetUserValues()
+	{
+		$query = \OC_DB::prepare('INSERT INTO `*PREFIX*preferences` VALUES(?, ?, ?, ?)');
+		$query->execute(array('SomeUser', 'testGetUserValues', 'somekey', 'somevalue'));
+		$query->execute(array('AnotherUser', 'testGetUserValues', 'somekey', 'someothervalue'));
+		$query->execute(array('AUser', 'testGetUserValues', 'somekey', 'somevalue'));
+
+		$preferences = new OC\Preferences(\OC_DB::getConnection());
+		$users = array('SomeUser', 'AnotherUser', 'NoValueSet');
+
+		$values = $preferences->getValueForUsers('testGetUserValues', 'somekey', $users);
+		$this->assertUserValues($values);
+
+		// Add a lot of users so the array is chunked
+		for ($i = 1; $i <= 75; $i++) {
+			array_unshift($users, 'NoValueBefore#' . $i);
+			array_push($users, 'NoValueAfter#' . $i);
+		}
+
+		$values = $preferences->getValueForUsers('testGetUserValues', 'somekey', $users);
+		$this->assertUserValues($values);
+
+		// Clean DB after the test
+		$query = \OC_DB::prepare('DELETE FROM `*PREFIX*preferences` WHERE `appid` = ?');
+		$query->execute(array('testGetUserValues'));
+	}
+
+	protected function assertUserValues($values) {
+		$this->assertEquals(2, sizeof($values));
+
+		$this->assertArrayHasKey('SomeUser', $values);
+		$this->assertEquals('somevalue', $values['SomeUser']);
+
+		$this->assertArrayHasKey('AnotherUser', $values);
+		$this->assertEquals('someothervalue', $values['AnotherUser']);
+	}
+
+	public function testGetValueUsers()
+	{
+		// Prepare data
+		$query = \OC_DB::prepare('INSERT INTO `*PREFIX*preferences` VALUES(?, ?, ?, ?)');
+		$query->execute(array('SomeUser', 'testGetUsersForValue', 'somekey', 'somevalue'));
+		$query->execute(array('AnotherUser', 'testGetUsersForValue', 'somekey', 'someothervalue'));
+		$query->execute(array('AUser', 'testGetUsersForValue', 'somekey', 'somevalue'));
+
+		$preferences = new OC\Preferences(\OC_DB::getConnection());
+		$result = $preferences->getUsersForValue('testGetUsersForValue', 'somekey', 'somevalue');
+		sort($result);
+		$this->assertEquals(array('AUser', 'SomeUser'), $result);
+
+		// Clean DB after the test
+		$query = \OC_DB::prepare('DELETE FROM `*PREFIX*preferences` WHERE `appid` = ?');
+		$query->execute(array('testGetUsersForValue'));
+	}
+
+	public function testDeleteKey()
+	{
+		$connectionMock = $this->getMock('\OC\DB\Connection', array(), array(), '', false);
+		$connectionMock->expects($this->once())
+			->method('delete')
+			->with($this->equalTo('*PREFIX*preferences'),
+				$this->equalTo(
+					array(
+						'userid' => 'grg',
+						'appid' => 'bar',
+						'configkey' => 'foo',
+					)
+				));
+
+		$preferences = new OC\Preferences($connectionMock);
+		$preferences->deleteKey('grg', 'bar', 'foo');
+	}
+
+	public function testDeleteApp()
+	{
+		$connectionMock = $this->getMock('\OC\DB\Connection', array(), array(), '', false);
+		$connectionMock->expects($this->once())
+			->method('delete')
+			->with($this->equalTo('*PREFIX*preferences'),
+				$this->equalTo(
+					array(
+						'userid' => 'grg',
+						'appid' => 'bar',
+					)
+				));
+
+		$preferences = new OC\Preferences($connectionMock);
+		$preferences->deleteApp('grg', 'bar');
+	}
+
+	public function testDeleteUser()
+	{
+		$connectionMock = $this->getMock('\OC\DB\Connection', array(), array(), '', false);
+		$connectionMock->expects($this->once())
+			->method('delete')
+			->with($this->equalTo('*PREFIX*preferences'),
+				$this->equalTo(
+					array(
+						'userid' => 'grg',
+					)
+				));
+
+		$preferences = new OC\Preferences($connectionMock);
+		$preferences->deleteUser('grg');
+	}
+
+	public function testDeleteAppFromAllUsers()
+	{
+		$connectionMock = $this->getMock('\OC\DB\Connection', array(), array(), '', false);
+		$connectionMock->expects($this->once())
+			->method('delete')
+			->with($this->equalTo('*PREFIX*preferences'),
+				$this->equalTo(
+					array(
+						'appid' => 'bar',
+					)
+				));
+
+		$preferences = new OC\Preferences($connectionMock);
+		$preferences->deleteAppFromAllUsers('bar');
+	}
+}
diff --git a/tests/lib/preferences.php b/tests/lib/preferences.php
index d31b0257bad7f59df5a6ed220f690cd0e789db39..fe8e3e8b48c3ddd33816c3369c52622d1516161e 100644
--- a/tests/lib/preferences.php
+++ b/tests/lib/preferences.php
@@ -7,161 +7,6 @@
  * See the COPYING-README file.
  */
 
-class Test_Preferences extends PHPUnit_Framework_TestCase {
-	public static function setUpBeforeClass() {
-		$query = \OC_DB::prepare('INSERT INTO `*PREFIX*preferences` VALUES(?, ?, ?, ?)');
-		$query->execute(array("Someuser", "someapp", "somekey", "somevalue"));
-
-		$query->execute(array("Someuser", "getusersapp", "somekey", "somevalue"));
-		$query->execute(array("Anotheruser", "getusersapp", "somekey", "someothervalue"));
-		$query->execute(array("Anuser", "getusersapp", "somekey", "somevalue"));
-
-		$query->execute(array("Someuser", "getappsapp", "somekey", "somevalue"));
-
-		$query->execute(array("Someuser", "getkeysapp", "firstkey", "somevalue"));
-		$query->execute(array("Someuser", "getkeysapp", "anotherkey", "somevalue"));
-		$query->execute(array("Someuser", "getkeysapp", "key-tastic", "somevalue"));
-
-		$query->execute(array("Someuser", "getvalueapp", "key", "a value for a key"));
-
-		$query->execute(array("Deleteuser", "deleteapp", "deletekey", "somevalue"));
-		$query->execute(array("Deleteuser", "deleteapp", "somekey", "somevalue"));
-		$query->execute(array("Deleteuser", "someapp", "somekey", "somevalue"));
-	}
-
-	public static function tearDownAfterClass() {
-		$query = \OC_DB::prepare('DELETE FROM `*PREFIX*preferences` WHERE `userid` = ?');
-		$query->execute(array('Someuser'));
-		$query->execute(array('Anotheruser'));
-		$query->execute(array('Anuser'));
-	}
-
-	public function testGetUsers() {
-		$query = \OC_DB::prepare('SELECT DISTINCT `userid` FROM `*PREFIX*preferences`');
-		$result = $query->execute();
-		$expected = array();
-		while ($row = $result->fetchRow()) {
-			$expected[] = $row['userid'];
-		}
-
-		$this->assertEquals($expected, \OC_Preferences::getUsers());
-	}
-
-	public function testGetApps() {
-		$query = \OC_DB::prepare('SELECT DISTINCT `appid` FROM `*PREFIX*preferences` WHERE `userid` = ?');
-		$result = $query->execute(array('Someuser'));
-		$expected = array();
-		while ($row = $result->fetchRow()) {
-			$expected[] = $row['appid'];
-		}
-
-		$this->assertEquals($expected, \OC_Preferences::getApps('Someuser'));
-	}
-
-	public function testGetKeys() {
-		$query = \OC_DB::prepare('SELECT DISTINCT `configkey` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ?');
-		$result = $query->execute(array('Someuser', 'getkeysapp'));
-		$expected = array();
-		while ($row = $result->fetchRow()) {
-			$expected[] = $row['configkey'];
-		}
-
-		$this->assertEquals($expected, \OC_Preferences::getKeys('Someuser', 'getkeysapp'));
-	}
-
-	public function testGetValue() {
-		$this->assertNull(\OC_Preferences::getValue('nonexistant', 'nonexistant', 'nonexistant'));
-
-		$this->assertEquals('default', \OC_Preferences::getValue('nonexistant', 'nonexistant', 'nonexistant', 'default'));
-
-		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
-		$result = $query->execute(array('Someuser', 'getvalueapp', 'key'));
-		$row = $result->fetchRow();
-		$expected = $row['configvalue'];
-		$this->assertEquals($expected, \OC_Preferences::getValue('Someuser', 'getvalueapp', 'key'));
-	}
-
-	public function testSetValue() {
-		$this->assertTrue(\OC_Preferences::setValue('Someuser', 'setvalueapp', 'newkey', 'newvalue'));
-		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
-		$result = $query->execute(array('Someuser', 'setvalueapp', 'newkey'));
-		$row = $result->fetchRow();
-		$value = $row['configvalue'];
-		$this->assertEquals('newvalue', $value);
-
-		$this->assertTrue(\OC_Preferences::setValue('Someuser', 'setvalueapp', 'newkey', 'othervalue'));
-		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
-		$result = $query->execute(array('Someuser', 'setvalueapp', 'newkey'));
-		$row = $result->fetchRow();
-		$value = $row['configvalue'];
-		$this->assertEquals('othervalue', $value);
-	}
-
-	public function testSetValueWithPreCondition() {
-		// remove existing key
-		$this->assertTrue(\OC_Preferences::deleteKey('Someuser', 'setvalueapp', 'newkey'));
-
-		// add new preference with pre-condition should fails
-		$this->assertFalse(\OC_Preferences::setValue('Someuser', 'setvalueapp', 'newkey', 'newvalue', 'preCondition'));
-		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
-		$result = $query->execute(array('Someuser', 'setvalueapp', 'newkey'));
-		$row = $result->fetchRow();
-		$this->assertFalse($row);
-
-		// add new preference without pre-condition should insert the new value
-		$this->assertTrue(\OC_Preferences::setValue('Someuser', 'setvalueapp', 'newkey', 'newvalue'));
-		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
-		$result = $query->execute(array('Someuser', 'setvalueapp', 'newkey'));
-		$row = $result->fetchRow();
-		$value = $row['configvalue'];
-		$this->assertEquals('newvalue', $value);
-
-		// wrong pre-condition, value should stay the same
-		$this->assertFalse(\OC_Preferences::setValue('Someuser', 'setvalueapp', 'newkey', 'othervalue', 'preCondition'));
-		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
-		$result = $query->execute(array('Someuser', 'setvalueapp', 'newkey'));
-		$row = $result->fetchRow();
-		$value = $row['configvalue'];
-		$this->assertEquals('newvalue', $value);
-
-		// correct pre-condition, value should change
-		$this->assertTrue(\OC_Preferences::setValue('Someuser', 'setvalueapp', 'newkey', 'othervalue', 'newvalue'));
-		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
-		$result = $query->execute(array('Someuser', 'setvalueapp', 'newkey'));
-		$row = $result->fetchRow();
-		$value = $row['configvalue'];
-		$this->assertEquals('othervalue', $value);
-	}
-
-	public function testDeleteKey() {
-		$this->assertTrue(\OC_Preferences::deleteKey('Deleteuser', 'deleteapp', 'deletekey'));
-		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?');
-		$result = $query->execute(array('Deleteuser', 'deleteapp', 'deletekey'));
-		$this->assertEquals(0, count($result->fetchAll()));
-	}
-
-	public function testDeleteApp() {
-		$this->assertTrue(\OC_Preferences::deleteApp('Deleteuser', 'deleteapp'));
-		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ? AND `appid` = ?');
-		$result = $query->execute(array('Deleteuser', 'deleteapp'));
-		$this->assertEquals(0, count($result->fetchAll()));
-	}
-
-	public function testDeleteUser() {
-		$this->assertTrue(\OC_Preferences::deleteUser('Deleteuser'));
-		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `userid` = ?');
-		$result = $query->execute(array('Deleteuser'));
-		$this->assertEquals(0, count($result->fetchAll()));
-	}
-
-	public function testDeleteAppFromAllUsers() {
-		$this->assertTrue(\OC_Preferences::deleteAppFromAllUsers('someapp'));
-		$query = \OC_DB::prepare('SELECT `configvalue` FROM `*PREFIX*preferences` WHERE `appid` = ?');
-		$result = $query->execute(array('someapp'));
-		$this->assertEquals(0, count($result->fetchAll()));
-	}
-}
-
 class Test_Preferences_Object extends PHPUnit_Framework_TestCase {
 	public function testGetUsers()
 	{
@@ -185,10 +30,69 @@ class Test_Preferences_Object extends PHPUnit_Framework_TestCase {
 		$connectionMock = $this->getMock('\OC\DB\Connection', array(), array(), '', false);
 		$connectionMock->expects($this->exactly(2))
 			->method('fetchColumn')
-			->with($this->equalTo('SELECT COUNT(*) FROM `*PREFIX*preferences`'
+			->with($this->equalTo('SELECT `configvalue` FROM `*PREFIX*preferences`'
+				.' WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?'),
+				$this->equalTo(array('grg', 'bar', 'foo')))
+			->will($this->onConsecutiveCalls(false, 'v1'));
+		$connectionMock->expects($this->once())
+			->method('insert')
+			->with($this->equalTo('*PREFIX*preferences'),
+				$this->equalTo(
+					array(
+						'userid' => 'grg',
+						'appid' => 'bar',
+						'configkey' => 'foo',
+						'configvalue' => 'v1',
+					)
+				));
+		$connectionMock->expects($this->once())
+			->method('executeUpdate')
+			->with($this->equalTo("UPDATE `*PREFIX*preferences` SET `configvalue` = ?"
+						. " WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?"),
+				$this->equalTo(array('v2', 'grg', 'bar', 'foo'))
+				);
+
+		$preferences = new OC\Preferences($connectionMock);
+		$preferences->setValue('grg', 'bar', 'foo', 'v1');
+		$preferences->setValue('grg', 'bar', 'foo', 'v2');
+	}
+
+	public function testSetValueUnchanged() {
+		$connectionMock = $this->getMock('\OC\DB\Connection', array(), array(), '', false);
+		$connectionMock->expects($this->exactly(3))
+			->method('fetchColumn')
+			->with($this->equalTo('SELECT `configvalue` FROM `*PREFIX*preferences`'
 				.' WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?'),
 				$this->equalTo(array('grg', 'bar', 'foo')))
-			->will($this->onConsecutiveCalls(0, 1));
+			->will($this->onConsecutiveCalls(false, 'v1', 'v1'));
+		$connectionMock->expects($this->once())
+			->method('insert')
+			->with($this->equalTo('*PREFIX*preferences'),
+				$this->equalTo(
+					array(
+						'userid' => 'grg',
+						'appid' => 'bar',
+						'configkey' => 'foo',
+						'configvalue' => 'v1',
+					)
+				));
+		$connectionMock->expects($this->never())
+			->method('executeUpdate');
+
+		$preferences = new OC\Preferences($connectionMock);
+		$preferences->setValue('grg', 'bar', 'foo', 'v1');
+		$preferences->setValue('grg', 'bar', 'foo', 'v1');
+		$preferences->setValue('grg', 'bar', 'foo', 'v1');
+	}
+
+	public function testSetValueUnchanged2() {
+		$connectionMock = $this->getMock('\OC\DB\Connection', array(), array(), '', false);
+		$connectionMock->expects($this->exactly(3))
+			->method('fetchColumn')
+			->with($this->equalTo('SELECT `configvalue` FROM `*PREFIX*preferences`'
+				.' WHERE `userid` = ? AND `appid` = ? AND `configkey` = ?'),
+				$this->equalTo(array('grg', 'bar', 'foo')))
+			->will($this->onConsecutiveCalls(false, 'v1', 'v2'));
 		$connectionMock->expects($this->once())
 			->method('insert')
 			->with($this->equalTo('*PREFIX*preferences'),
@@ -210,6 +114,7 @@ class Test_Preferences_Object extends PHPUnit_Framework_TestCase {
 		$preferences = new OC\Preferences($connectionMock);
 		$preferences->setValue('grg', 'bar', 'foo', 'v1');
 		$preferences->setValue('grg', 'bar', 'foo', 'v2');
+		$preferences->setValue('grg', 'bar', 'foo', 'v2');
 	}
 
 	public function testGetUserValues()