diff --git a/core/core.services.yml b/core/core.services.yml
index cbea99b..4fbb0e0 100644
--- a/core/core.services.yml
+++ b/core/core.services.yml
@@ -131,6 +131,7 @@ services:
     class: Drupal\Core\Logger\LoggerChannel
     factory_method: get
     factory_service: logger.factory
+    arguments: ['system']
   settings:
     class: Drupal\Component\Utility\Settings
     factory_class: Drupal\Component\Utility\Settings
diff --git a/core/lib/Drupal/Core/Logger/LoggerBase.php b/core/lib/Drupal/Core/Logger/LogMessageParserTrait.php
similarity index 78%
rename from core/lib/Drupal/Core/Logger/LoggerBase.php
rename to core/lib/Drupal/Core/Logger/LogMessageParserTrait.php
index e099640..808c7a8 100644
--- a/core/lib/Drupal/Core/Logger/LoggerBase.php
+++ b/core/lib/Drupal/Core/Logger/LogMessageParserTrait.php
@@ -2,17 +2,15 @@
 
 /**
  * @file
- * Contains \Drupal\Core\Logger\LoggerBase.
+ * Contains \Drupal\Core\Logger\LogMessageParserTrait.
  */
 
 namespace Drupal\Core\Logger;
 
-use Psr\Log\AbstractLogger;
-
 /**
- * Defines a base PSR3 compatible logger class.
+ * Defines a trait for parsing log messages and their placeholders.
  */
-abstract class LoggerBase extends AbstractLogger {
+trait LogMessageParserTrait {
 
   /**
    * Parses and transforms message and its placeholders to a common format.
@@ -28,15 +26,19 @@
    *
    * @param string $message
    *   The message that contains the placeholders.
+   *   If the message is in PSR3 style, it will be transformed to
+   *   \Drupal\Component\Utility\String::format() style.
    * @param array $context
    *   An array that may or may not contain placeholder variables.
+   *   $context['variables'] will contain the transformed variables.
    */
   protected function parseMessagePlaceholders(&$message, array &$context) {
     $variables = array();
     $has_ps3 = FALSE;
     if (($start = strpos($message, '{')) !== FALSE && strpos($message, '}') > $start) {
       $has_ps3 = TRUE;
-      // Replace PSR3 style messages containing placeholders.
+      // Transform PSR3 style messages containing placeholders to
+      // \Drupal\Component\Utility\String::format() style.
       $message = preg_replace('/\{(.*)\}/U', '@$1', $message);
     }
     foreach ($context as $key => $variable) {
diff --git a/core/lib/Drupal/Core/Logger/LoggerChannel.php b/core/lib/Drupal/Core/Logger/LoggerChannel.php
index d96c7cd..6ba39d9 100644
--- a/core/lib/Drupal/Core/Logger/LoggerChannel.php
+++ b/core/lib/Drupal/Core/Logger/LoggerChannel.php
@@ -8,15 +8,17 @@
 namespace Drupal\Core\Logger;
 
 use Drupal\Core\Session\AccountInterface;
-use Psr\Log\AbstractLogger;
 use Psr\Log\LoggerInterface;
+use Psr\Log\LoggerTrait;
 use Psr\Log\LogLevel;
 use Symfony\Component\HttpFoundation\Request;
 
 /**
  * Defines a logger channel that most implementations will use.
  */
-class LoggerChannel extends AbstractLogger {
+class LoggerChannel implements LoggerChannelInterface {
+
+  use LoggerTrait;
 
   /**
    * The name of the channel of this logger instance.
@@ -57,7 +59,7 @@ class LoggerChannel extends AbstractLogger {
    * @param string $channel
    *   The channel name for this instance.
    */
-  public function __construct($channel = 'system') {
+  public function __construct($channel) {
     $this->channel = $channel;
   }
 
@@ -98,42 +100,35 @@ public function log($level, $message, array $context = array()) {
   }
 
   /**
-   * Sets the request.
-   *
-   * @param \Symfony\Component\HttpFoundation\Request $request
-   *   The current request object.
+   * {@inheritdoc}
    */
   public function setRequest(Request $request = NULL) {
     $this->request = $request;
   }
 
   /**
-   * Sets the current user.
-   *
-   * @param \Drupal\Core\Session\AccountInterface $current_user
-   *   The current user object.
+   * {@inheritdoc}
    */
   public function setCurrentUser(AccountInterface $current_user = NULL) {
     $this->currentUser = $current_user;
   }
 
   /**
-   * Sets the loggers for this channel.
-   *
-   * @param array $loggers
-   *   An array of arrays of \Psr\Log\LoggerInterface keyed by priority.
+   * {@inheritdoc}
    */
   public function setLoggers(array $loggers) {
+    foreach ($loggers as $priority => $group) {
+      foreach ($group as $logger) {
+        if (!$logger instanceof LoggerInterface) {
+          throw new InvalidArgumentException('All loggers must implement \Psr\Log\LoggerInterface.');
+        }
+      }
+    }
     $this->loggers = $loggers;
   }
 
   /**
-   * Adds a logger.
-   *
-   * @param \Psr\Log\LoggerInterface $logger
-   *   The PSR-3 logger to add.
-   * @param int $priority
-   *   The priority of the logger being added.
+   * {@inheritdoc}
    */
   public function addLogger(LoggerInterface $logger, $priority = 0) {
     $this->loggers[$priority][] = $logger;
diff --git a/core/lib/Drupal/Core/Logger/LoggerChannelFactory.php b/core/lib/Drupal/Core/Logger/LoggerChannelFactory.php
index b489eaf..986af54 100644
--- a/core/lib/Drupal/Core/Logger/LoggerChannelFactory.php
+++ b/core/lib/Drupal/Core/Logger/LoggerChannelFactory.php
@@ -17,28 +17,23 @@
 class LoggerChannelFactory extends ContainerAware {
 
   /**
-   * Array of all instantiated logger channels.
+   * Array of all instantiated logger channels keyed by channel name.
    *
-   * @var array
+   * @var Drupal\Core\Logger\LoggerChannelInterface[]
    */
   protected $channels = array();
 
   /**
-   * Array of \Psr\Log\LoggerInterface objects.
+   * An array of arrays of \Psr\Log\LoggerInterface keyed by priority.
    *
    * @var array
    */
   protected $loggers = array();
 
   /**
-   * Retrieves the registered logger for the requested channel.
-   *
-   * If the channel does not exist, the default "system" channel is being used.
-   *
-   * @return \Psr\Log\LoggerInterface
-   *   The registered logger for this channel.
+   * {@inheritdoc}
    */
-  public function get($channel = 'system') {
+  public function get($channel) {
     if (!isset($this->channels[$channel])) {
       $instance = new LoggerChannel($channel);
 
@@ -60,17 +55,7 @@ public function get($channel = 'system') {
   }
 
   /**
-   * Adds a logger.
-   *
-   * Here is were all services tagged as 'logger' are being retrieved and then
-   * passed to the channels after instantiation.
-   *
-   * @param \Psr\Log\LoggerInterface $logger
-   *   The PSR-3 logger to add.
-   * @param int $priority
-   *   The priority of the logger being added.
-   *
-   * @see \Drupal\Core\DependencyInjection\Compiler\RegisterLoggersPass
+   * {@inheritdoc}
    */
   public function addLogger(LoggerInterface $logger, $priority = 0) {
     // Store it so we can pass it to potential new logger instances.
diff --git a/core/lib/Drupal/Core/Logger/LoggerChannelFactoryInterface.php b/core/lib/Drupal/Core/Logger/LoggerChannelFactoryInterface.php
new file mode 100644
index 0000000..67d178c
--- /dev/null
+++ b/core/lib/Drupal/Core/Logger/LoggerChannelFactoryInterface.php
@@ -0,0 +1,40 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Logger\LoggerChannelFactoryInterface.
+ */
+
+namespace Drupal\Core\Logger;
+
+use Psr\Log\LoggerInterface;
+
+/**
+ * Logger channel factory interface.
+ */
+interface LoggerChannelFactoryInterface {
+
+  /**
+   * Retrieves the registered logger for the requested channel.
+   *
+   * @return \Drupal\Core\Logger\LoggerChannelInterface
+   *   The registered logger for this channel.
+   */
+  public function get($channel);
+
+  /**
+   * Adds a logger.
+   *
+   * Here is were all services tagged as 'logger' are being retrieved and then
+   * passed to the channels after instantiation.
+   *
+   * @param \Psr\Log\LoggerInterface $logger
+   *   The PSR-3 logger to add.
+   * @param int $priority
+   *   The priority of the logger being added.
+   *
+   * @see \Drupal\Core\DependencyInjection\Compiler\RegisterLoggersPass
+   */
+  public function addLogger(LoggerInterface $logger, $priority = 0);
+
+}
diff --git a/core/lib/Drupal/Core/Logger/LoggerChannelInterface.php b/core/lib/Drupal/Core/Logger/LoggerChannelInterface.php
new file mode 100644
index 0000000..15d9741
--- /dev/null
+++ b/core/lib/Drupal/Core/Logger/LoggerChannelInterface.php
@@ -0,0 +1,53 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Logger\LoggerChannelInterface.
+ */
+
+namespace Drupal\Core\Logger;
+
+use Drupal\Core\Session\AccountInterface;
+use Psr\Log\LoggerInterface;
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Logger channel interface.
+ */
+interface LoggerChannelInterface extends LoggerInterface {
+
+  /**
+   * Sets the request.
+   *
+   * @param \Symfony\Component\HttpFoundation\Request|null $request
+   *   The current request object.
+   */
+  public function setRequest(Request $request = NULL);
+
+  /**
+   * Sets the current user.
+   *
+   * @param \Drupal\Core\Session\AccountInterface|null $current_user
+   *   The current user object.
+   */
+  public function setCurrentUser(AccountInterface $current_user = NULL);
+
+  /**
+   * Sets the loggers for this channel.
+   *
+   * @param array $loggers
+   *   An array of arrays of \Psr\Log\LoggerInterface keyed by priority.
+   */
+  public function setLoggers(array $loggers);
+
+  /**
+   * Adds a logger.
+   *
+   * @param \Psr\Log\LoggerInterface $logger
+   *   The PSR-3 logger to add.
+   * @param int $priority
+   *   The priority of the logger being added.
+   */
+  public function addLogger(LoggerInterface $logger, $priority = 0);
+
+}
diff --git a/core/modules/dblog/dblog.module b/core/modules/dblog/dblog.module
index cc6d4f3..4fbbfb0 100644
--- a/core/modules/dblog/dblog.module
+++ b/core/modules/dblog/dblog.module
@@ -11,8 +11,6 @@
  * @see watchdog()
  */
 
-use Drupal\Core\Database\Database;
-
 /**
  * Implements hook_help().
  */
diff --git a/core/modules/dblog/lib/Drupal/dblog/Logger/DbLog.php b/core/modules/dblog/lib/Drupal/dblog/Logger/DbLog.php
index 36b553e..034c6ba 100644
--- a/core/modules/dblog/lib/Drupal/dblog/Logger/DbLog.php
+++ b/core/modules/dblog/lib/Drupal/dblog/Logger/DbLog.php
@@ -8,12 +8,17 @@
 namespace Drupal\dblog\Logger;
 
 use Drupal\Core\Database\Connection;
-use Drupal\Core\Logger\LoggerBase;
+use Drupal\Core\Logger\LogMessageParserTrait;
+use Psr\Log\LoggerInterface;
+use Psr\Log\LoggerTrait;
 
 /**
  * Logs events in the watchdog database table.
  */
-class DbLog extends LoggerBase {
+class DbLog implements LoggerInterface {
+
+  use LoggerTrait;
+  use LogMessageParserTrait;
 
   /**
    * The database connection object.
@@ -39,7 +44,7 @@ public function log($level, $message, array $context = array()) {
     // Remove any backtraces since they may contain an unserializable variable.
     unset($context['backtrace']);
 
-    // Convert PSR3-style messages to format_string() style, so they can be
+    // Convert PSR3-style messages to String::format() style, so they can be
     // translated too in runtime.
     $this->parseMessagePlaceholders($message, $context);
 
diff --git a/core/modules/syslog/lib/Drupal/syslog/Logger/SysLog.php b/core/modules/syslog/lib/Drupal/syslog/Logger/SysLog.php
index 2c19f0a..b0e31f8 100644
--- a/core/modules/syslog/lib/Drupal/syslog/Logger/SysLog.php
+++ b/core/modules/syslog/lib/Drupal/syslog/Logger/SysLog.php
@@ -8,12 +8,17 @@
 namespace Drupal\syslog\Logger;
 
 use Drupal\Core\Config\ConfigFactory;
-use Drupal\Core\Logger\LoggerBase;
+use Drupal\Core\Logger\LogMessageParserTrait;
+use Psr\Log\LoggerInterface;
+use Psr\Log\LoggerTrait;
 
 /**
  * Redirects logging messages to syslog.
  */
-class SysLog extends LoggerBase {
+class SysLog implements LoggerInterface {
+
+  use LoggerTrait;
+  use LogMessageParserTrait;
 
   /**
    * A configuration object containin syslog settings.
diff --git a/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.module b/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.module
index 9a0676d..f91afde 100644
--- a/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.module
+++ b/core/modules/system/tests/modules/entity_cache_test/entity_cache_test.module
@@ -17,7 +17,7 @@
  * @see EntityApiInfoTest::testEntityInfoCacheModulesEnabled()
  */
 function entity_cache_test_modules_installed($modules_enabled) {
-  $info = entity_get_info('entity_cache_test');
+  $info = \Drupal::entityManager()->getDefinition('entity_cache_test');
   // Store the information in a system variable to analyze it later in the
   // test case.
   \Drupal::state()->set('entity_cache_test', $info);
diff --git a/core/tests/Drupal/Tests/Core/Logger/LoggerBaseTest.php b/core/tests/Drupal/Tests/Core/Logger/LogMessageParserTraitTest.php
similarity index 80%
rename from core/tests/Drupal/Tests/Core/Logger/LoggerBaseTest.php
rename to core/tests/Drupal/Tests/Core/Logger/LogMessageParserTraitTest.php
index 0f93256..a7b81cf 100644
--- a/core/tests/Drupal/Tests/Core/Logger/LoggerBaseTest.php
+++ b/core/tests/Drupal/Tests/Core/Logger/LogMessageParserTraitTest.php
@@ -2,25 +2,28 @@
 
 /**
  * @file
- * Contains \Drupal\Tests\Core\Logger\LoggerBaseTest
+ * Contains \Drupal\Tests\Core\Logger\LogMessageParserTraitTest
  */
 
 namespace Drupal\Tests\Core\Logger;
 
-use Drupal\Core\Logger\LoggerBase;
 use Drupal\Tests\UnitTestCase;
 
 /**
- * Tests the base logger object.
+ * Tests the log message parser trait.
  *
+ * @see \Drupal\Core\Logger\LogMessageParserTrait
+ * @coversDefaultClass \Drupal\Core\Logger\LogMessageParserTrait
+ *
+ * @group Drupal
  * @group Logger
  */
-class LoggerBaseTest extends UnitTestCase {
+class LogMessageParserTraitTest extends UnitTestCase {
 
   public static function getInfo() {
     return array(
-      'name' => 'Logger base',
-      'description' => 'Unit tests for the logger base.',
+      'name' => 'Log message parser',
+      'description' => 'Unit tests for the log message parser trait.',
       'group' => 'Logger',
     );
   }
@@ -29,11 +32,11 @@ public static function getInfo() {
    * {@inheritdoc}
    */
   protected function setUp() {
-    $this->logger = $this->getMockForAbstractClass('Drupal\Core\Logger\LoggerBase');
+    $this->logger = $this->getObjectForTrait('Drupal\Core\Logger\LogMessageParserTrait');
   }
 
   /**
-   * Test for LoggerBase::parseMessagePlaceholders()
+   * Test for LogMessageParserTrait::parseMessagePlaceholders()
    *
    * @param array $value
    *   An array containing:
@@ -45,9 +48,10 @@ protected function setUp() {
    *    - context: The expected values of the placeholders.
    *
    * @dataProvider providerTestParseMessagePlaceholders
+   * @covers ::parseMessagePlaceholders
    */
   public function testParseMessagePlaceholders(array $value, array $expected) {
-    $class = new \ReflectionClass('Drupal\Core\Logger\LoggerBase');
+    $class = new \ReflectionClass($this->logger);
     $method = $class->getMethod('parseMessagePlaceholders');
     $method->setAccessible(TRUE);
     $method->invokeArgs($this->logger, array(&$value['message'], &$value['context']));
diff --git a/core/tests/Drupal/Tests/Core/Logger/LoggerChannelFactoryTest.php b/core/tests/Drupal/Tests/Core/Logger/LoggerChannelFactoryTest.php
new file mode 100644
index 0000000..61b3415
--- /dev/null
+++ b/core/tests/Drupal/Tests/Core/Logger/LoggerChannelFactoryTest.php
@@ -0,0 +1,60 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\Core\Logger\LoggerChannelFactoryTest
+ */
+
+namespace Drupal\Tests\Logger;
+
+use Drupal\Core\Logger\LoggerChannelFactory;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\Tests\UnitTestCase;
+use Symfony\Component\HttpFoundation\Request;
+
+// @todo Remove once watchdog() is removed.
+if (!defined('WATCHDOG_EMERGENCY')) {
+  define('WATCHDOG_EMERGENCY', 0);
+  define('WATCHDOG_ALERT', 1);
+  define('WATCHDOG_CRITICAL', 2);
+  define('WATCHDOG_ERROR', 3);
+  define('WATCHDOG_WARNING', 4);
+  define('WATCHDOG_NOTICE', 5);
+  define('WATCHDOG_INFO', 6);
+  define('WATCHDOG_DEBUG', 7);
+}
+
+/**
+ * Tests the logger channel factory.
+ *
+ * @see \Drupal\Core\Logger\LoggerChannelFactory
+ * @coversDefaultClass \Drupal\Core\Logger\LoggerChannelFactory
+ *
+ * @group Drupal
+ * @group Logger
+ */
+class LoggerChannelFactoryTest extends UnitTestCase {
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Logger channel factory',
+      'description' => 'Unit tests for the logger channel factory object.',
+      'group' => 'Logger',
+    );
+  }
+
+  /**
+   * Test for LoggerChannelFactory::get()
+   *
+   * @covers ::get
+   */
+  public function testGet() {
+    $factory = new LoggerChannelFactory();
+    $factory->setContainer($this->getMock('Symfony\Component\DependencyInjection\ContainerInterface'));
+
+    // Ensure that when called with the same argument, always the same instance
+    // will be returned.
+    $this->assertEquals($factory->get('test'), $factory->get('test'));
+  }
+
+}
diff --git a/core/tests/Drupal/Tests/Core/Logger/LoggerChannelTest.php b/core/tests/Drupal/Tests/Core/Logger/LoggerChannelTest.php
new file mode 100644
index 0000000..64c206e
--- /dev/null
+++ b/core/tests/Drupal/Tests/Core/Logger/LoggerChannelTest.php
@@ -0,0 +1,152 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\Core\Logger\LoggerChannelTest
+ */
+
+namespace Drupal\Tests\Logger;
+
+use Drupal\Core\Logger\LoggerChannel;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\Tests\UnitTestCase;
+use Symfony\Component\HttpFoundation\Request;
+
+// @todo Remove once watchdog() is removed.
+if (!defined('WATCHDOG_EMERGENCY')) {
+  define('WATCHDOG_EMERGENCY', 0);
+  define('WATCHDOG_ALERT', 1);
+  define('WATCHDOG_CRITICAL', 2);
+  define('WATCHDOG_ERROR', 3);
+  define('WATCHDOG_WARNING', 4);
+  define('WATCHDOG_NOTICE', 5);
+  define('WATCHDOG_INFO', 6);
+  define('WATCHDOG_DEBUG', 7);
+}
+
+/**
+ * Tests the logger channel.
+ *
+ * @see \Drupal\Core\Logger\LoggerChannel
+ * @coversDefaultClass \Drupal\Core\Logger\LoggerChannel
+ *
+ * @group Drupal
+ * @group Logger
+ */
+class LoggerChannelTest extends UnitTestCase {
+
+  public static function getInfo() {
+    return array(
+      'name' => 'Logger channel',
+      'description' => 'Unit tests for the logger channel object.',
+      'group' => 'Logger',
+    );
+  }
+
+  /**
+   * Test for LoggerChannel::log()
+   *
+   * @param callable $expected
+   *   An anonymous function to use with $this->callback() of the logger mock.
+   *   The function should check the $context array for expected values.
+   * @param \Symfony\Component\HttpFoundation\Request $request
+   *   Will be passed to the channel under test if present.
+   * @param \Drupal\Core\Session\AccountInterface $current_user
+   *   Will be passed to the channel under test if present.
+   *
+   * @dataProvider providerTestLog
+   * @covers ::log
+   * @covers ::setCurrentUser
+   * @covers ::setRequest
+   */
+  public function testLog(callable $expected, Request $request = NULL, AccountInterface $current_user = NULL) {
+    $channel = new LoggerChannel('test');
+    $message = $this->randomName();
+    $logger = $this->getMock('Psr\Log\LoggerInterface');
+    $logger->expects($this->once())
+      ->method('log')
+      ->with($this->anything(), $message, $this->callback($expected));
+    $channel->addLogger($logger);
+    if ($request) {
+      $channel->setRequest($request);
+    }
+    if ($current_user) {
+      $channel->setCurrentUser($current_user);
+    }
+    $channel->log(rand(0, 7), $message);
+  }
+
+  /**
+   * Test for LoggerChannel::addLoggers()
+   *
+   * @covers ::addLogger
+   * @covers ::sortLoggers
+   */
+  public function testSortLoggers() {
+    $channel = new LoggerChannel($this->randomName());
+    $index_order = '';
+    for ($i = 0; $i < 4; $i++) {
+      $logger = $this->getMock('Psr\Log\LoggerInterface');
+      $logger->expects($this->once())
+        ->method('log')
+        ->will($this->returnCallback(function () use ($i, &$index_order) {
+          // Append the $i to the index order, so that we know the order that
+          // loggers got called with.
+          $index_order .= $i;
+        }));
+      $channel->addLogger($logger, $i);
+    }
+
+    $channel->log(rand(0, 7), $this->randomName());
+    // Ensure that the logger added in the end fired first.
+    $this->assertEquals($index_order, '3210');
+  }
+
+  /**
+   * Data provider for self::testLog().
+   */
+  public function providerTestLog() {
+    $account_mock = $this->getMock('Drupal\Core\Session\AccountInterface');
+    $account_mock->expects($this->exactly(2))
+      ->method('id')
+      ->will($this->returnValue(1));
+
+    $request_mock = $this->getMock('Symfony\Component\HttpFoundation\Request');
+    $request_mock->expects($this->exactly(2))
+      ->method('getClientIp')
+      ->will($this->returnValue('127.0.0.1'));
+    $request_mock->headers = $this->getMock('Symfony\Component\HttpFoundation\ParameterBag');
+
+    // No request or account.
+    $cases [] = array(
+      function ($context) {
+        return $context['channel'] == 'test' && empty($contex['uid']) && empty($context['ip']);
+      },
+    );
+    // With account but not request.
+    $cases [] = array(
+      function ($context) {
+        return $context['uid'] === 1 && empty($context['ip']);
+      },
+      NULL,
+      $account_mock,
+    );
+    // With request but not account.
+    $cases [] = array(
+      function ($context) {
+        return $context['ip'] === '127.0.0.1' && empty($contex['uid']);
+      },
+      $request_mock,
+    );
+    // Both request and account.
+    $cases [] = array(
+      function ($context) {
+        return $context['ip'] === '127.0.0.1' && $context['uid'] === 1;
+      },
+      $request_mock,
+      $account_mock,
+    );
+    return $cases;
+  }
+
+}