diff --git a/core/lib/Drupal/Core/CoreBundle.php b/core/lib/Drupal/Core/CoreBundle.php
index 94b5109..f257f9f 100644
--- a/core/lib/Drupal/Core/CoreBundle.php
+++ b/core/lib/Drupal/Core/CoreBundle.php
@@ -380,15 +380,15 @@ protected function registerPathProcessors(ContainerBuilder $container) {
     $container->register('path_processor_manager', 'Drupal\Core\PathProcessor\PathProcessorManager');
     // Register the processor that urldecodes the path.
     $container->register('path_processor_decode', 'Drupal\Core\PathProcessor\PathProcessorDecode')
-      ->addTag('inbound_path_processor', array('priority' => 300));
+      ->addTag('path_processor_inbound', array('priority' => 1000));
     // Register the processor that resolves the front page.
     $container->register('path_processor_front', 'Drupal\Core\PathProcessor\PathProcessorFront')
       ->addArgument(new Reference('config.factory'))
-      ->addTag('inbound_path_processor', array('priority' => 200));
+      ->addTag('path_processor_inbound', array('priority' => 200));
     // Register the alias path processor.
     $container->register('path_processor_alias', 'Drupal\Core\PathProcessor\PathProcessorAlias')
       ->addArgument(new Reference('path.alias_manager'))
-      ->addTag('inbound_path_processor', array('priority' => 100));
+      ->addTag('path_processor_inbound', array('priority' => 100));
 
     // Add the compiler pass that will process the tagged services.
     $container->addCompilerPass(new RegisterPathProcessorsPass());
diff --git a/core/lib/Drupal/Core/DependencyInjection/Compiler/RegisterPathProcessorsPass.php b/core/lib/Drupal/Core/DependencyInjection/Compiler/RegisterPathProcessorsPass.php
index fd3cb5b..6e298da 100644
--- a/core/lib/Drupal/Core/DependencyInjection/Compiler/RegisterPathProcessorsPass.php
+++ b/core/lib/Drupal/Core/DependencyInjection/Compiler/RegisterPathProcessorsPass.php
@@ -17,7 +17,7 @@
 class RegisterPathProcessorsPass implements CompilerPassInterface {
 
   /**
-   * Adds services tagged 'inbound_path_processor' to the path processor manager.
+   * Adds services tagged 'path_processor_inbound' to the path processor manager.
    *
    * @param \Symfony\Component\DependencyInjection\ContainerBuilder $container
    *  The container to process.
@@ -27,7 +27,7 @@ public function process(ContainerBuilder $container) {
       return;
     }
     $manager = $container->getDefinition('path_processor_manager');
-    foreach ($container->findTaggedServiceIds('inbound_path_processor') as $id => $attributes) {
+    foreach ($container->findTaggedServiceIds('path_processor_inbound') as $id => $attributes) {
       $priority = isset($attributes[0]['priority']) ? $attributes[0]['priority'] : 0;
       $manager->addMethodCall('addInbound', array(new Reference($id), $priority));
     }
diff --git a/core/lib/Drupal/Core/PathProcessor/PathProcessorManager.php b/core/lib/Drupal/Core/PathProcessor/PathProcessorManager.php
index b79f0c7..1d0adff 100644
--- a/core/lib/Drupal/Core/PathProcessor/PathProcessorManager.php
+++ b/core/lib/Drupal/Core/PathProcessor/PathProcessorManager.php
@@ -45,10 +45,6 @@ class PathProcessorManager implements InboundPathProcessorInterface {
    *   The priority of the processor being added.
    */
   public function addInbound(InboundPathProcessorInterface $processor, $priority = 0) {
-    if (empty($this->inboundProcessors[$priority])) {
-      $this->inboundProcessors[$priority] = array();
-    }
-
     $this->inboundProcessors[$priority][] = $processor;
     $this->sortedInbound = array();
   }
diff --git a/core/modules/language/lib/Drupal/language/HttpKernel/PathProcessorLanguage.php b/core/modules/language/lib/Drupal/language/HttpKernel/PathProcessorLanguage.php
index 3954451..ad16ac6 100644
--- a/core/modules/language/lib/Drupal/language/HttpKernel/PathProcessorLanguage.php
+++ b/core/modules/language/lib/Drupal/language/HttpKernel/PathProcessorLanguage.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Contains Drupal\language\PathProcessorLanguage.
+ * Contains Drupal\language\HttpKernel\PathProcessorLanguage.
  */
 
 namespace Drupal\language\HttpKernel;
diff --git a/core/modules/language/lib/Drupal/language/LanguageBundle.php b/core/modules/language/lib/Drupal/language/LanguageBundle.php
index 458bff5..1e788aa 100644
--- a/core/modules/language/lib/Drupal/language/LanguageBundle.php
+++ b/core/modules/language/lib/Drupal/language/LanguageBundle.php
@@ -23,7 +23,7 @@ public function build(ContainerBuilder $container) {
     // Register the language-based path processor.
     $container->register('path_processor_language', 'Drupal\language\HttpKernel\PathProcessorLanguage')
       ->addArgument(new Reference('module_handler'))
-      ->addTag('inbound_path_processor', array('priority' => 250));
+      ->addTag('path_processor_inbound', array('priority' => 300));
   }
 
 }
diff --git a/core/modules/system/lib/Drupal/system/Tests/Path/AliasTest.php b/core/modules/system/lib/Drupal/system/Tests/Path/AliasTest.php
index 275e1c4..5dc3158 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Path/AliasTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Path/AliasTest.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Definition of Drupal\system\Tests\Path\CrudTest.
+ * Contains Drupal\system\Tests\Path\AliasTest.
  */
 
 namespace Drupal\system\Tests\Path;
@@ -15,7 +15,7 @@
 /**
  * Tests path alias CRUD and lookup functionality.
  */
-class AliasTest extends DrupalUnitTestBase {
+class AliasTest extends PathUnitTestBase {
 
   public static function getInfo() {
     return array(
@@ -25,18 +25,6 @@ public static function getInfo() {
     );
   }
 
-  public function setUp() {
-    parent::setUp();
-    $this->fixtures = new UrlAliasFixtures();
-  }
-
-  public function tearDown() {
-    $this->fixtures->dropTables(Database::getConnection());
-
-    parent::tearDown();
-  }
-
-
   function testCRUD() {
     //Prepare database table.
     $connection = Database::getConnection();
diff --git a/core/modules/system/lib/Drupal/system/Tests/Path/PathUnitTestBase.php b/core/modules/system/lib/Drupal/system/Tests/Path/PathUnitTestBase.php
new file mode 100644
index 0000000..c24506d
--- /dev/null
+++ b/core/modules/system/lib/Drupal/system/Tests/Path/PathUnitTestBase.php
@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * @file
+ * Contains Drupal\system\Tests\Path\PathUnitTestBase.
+ */
+
+namespace Drupal\system\Tests\Path;
+
+use Drupal\simpletest\DrupalUnitTestBase;
+use Drupal\Core\Database\Database;
+
+/**
+ * Defines a base class for path unit testing.
+ */
+class PathUnitTestBase extends DrupalUnitTestBase {
+
+  public function setUp() {
+    parent::setUp();
+    $this->fixtures = new UrlAliasFixtures();
+  }
+
+  public function tearDown() {
+    $this->fixtures->dropTables(Database::getConnection());
+
+    parent::tearDown();
+  }
+}
diff --git a/core/modules/system/lib/Drupal/system/Tests/Path/UrlAliasFixtures.php b/core/modules/system/lib/Drupal/system/Tests/Path/UrlAliasFixtures.php
index 6fb02da..a51e3bf 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Path/UrlAliasFixtures.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Path/UrlAliasFixtures.php
@@ -16,7 +16,7 @@ class UrlAliasFixtures {
    *   The connection to use to create the tables.
    */
   public function createTables(Connection $connection) {
-    $tables = $this->urlAliasTableDefinition();
+    $tables = $this->tableDefinition();
     $schema = $connection->schema();
 
     foreach ($tables as $name => $table) {
@@ -32,7 +32,7 @@ public function createTables(Connection $connection) {
    *   The connection to use to drop the tables.
    */
   public function dropTables(Connection $connection) {
-    $tables = $this->urlAliasTableDefinition();
+    $tables = $this->tableDefinition();
     $schema = $connection->schema();
 
     foreach ($tables as $name => $table) {
@@ -77,7 +77,7 @@ public function sampleUrlAliases() {
    * @return array
    *   Table definitions.
    */
-  public function urlAliasTableDefinition() {
+  public function tableDefinition() {
     $tables = array();
 
     module_load_install('system');
diff --git a/core/modules/system/lib/Drupal/system/Tests/PathProcessor/PathProcessorFixtures.php b/core/modules/system/lib/Drupal/system/Tests/PathProcessor/PathProcessorFixtures.php
new file mode 100644
index 0000000..dbc987d
--- /dev/null
+++ b/core/modules/system/lib/Drupal/system/Tests/PathProcessor/PathProcessorFixtures.php
@@ -0,0 +1,27 @@
+<?php
+
+namespace Drupal\system\Tests\PathProcessor;
+
+use Drupal\Core\Database\Connection;
+use Drupal\system\Tests\Path\UrlAliasFixtures;
+
+/**
+ * Utility methods to provide necessary database tables for tests.
+ */
+class PathProcessorFixtures extends UrlAliasFixtures {
+
+  /**
+   * Overrides Drupal\system\Tests\Path\UrlAliasFixtures::tableDefinition() .
+   */
+  public function tableDefinition() {
+    // In addition to the tables added by the parent method, we also need the
+    // language and variable tables for the path processor tests.
+    $tables = parent::tableDefinition();
+    $schema = system_schema();
+    $tables['variable'] = $schema['variable'];
+    module_load_install('language');
+    $schema = language_schema();
+    $tables['language'] = $schema['language'];
+    return $tables;
+  }
+}
diff --git a/core/modules/system/lib/Drupal/system/Tests/PathProcessor/PathProcessorTest.php b/core/modules/system/lib/Drupal/system/Tests/PathProcessor/PathProcessorTest.php
new file mode 100644
index 0000000..5b10c2a
--- /dev/null
+++ b/core/modules/system/lib/Drupal/system/Tests/PathProcessor/PathProcessorTest.php
@@ -0,0 +1,124 @@
+<?php
+
+/**
+ * @file
+ * Contains Drupal\system\Tests\PathProcessor\PathProcessorTest.
+ */
+
+namespace Drupal\system\Tests\PathProcessor;
+
+use Drupal\system\Tests\Path\PathUnitTestBase;
+use Drupal\Core\Database\Database;
+use Drupal\Core\Path\Path;
+use Drupal\Core\Path\AliasManager;
+use Drupal\Core\PathProcessor\PathProcessorAlias;
+use Drupal\Core\PathProcessor\PathProcessorDecode;
+use Drupal\Core\PathProcessor\PathProcessorFront;
+use Drupal\Core\PathProcessor\PathProcessorManager;
+use Drupal\language\HttpKernel\PathProcessorLanguage;
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Tests path processor functionality.
+ */
+class PathProcessorTest extends PathUnitTestBase {
+
+  public static function getInfo() {
+    return array(
+      'name' => t('Path Processor Unit Tests'),
+      'description' => t('Tests processing of the inbound path.'),
+      'group' => t('Path API'),
+    );
+  }
+
+  public function setUp() {
+    parent::setUp();
+    $this->fixtures = new PathProcessorFixtures();
+  }
+
+  /**
+   * Tests resolving the inbound path to the system path.
+   */
+  function testProcessInbound() {
+
+    // Ensure all tables needed for these tests are created.
+    $connection = Database::getConnection();
+    $this->fixtures->createTables($connection);
+
+    // Create dependecies needed by various path processors.
+    $alias_manager = new AliasManager($connection, $this->container->get('state'), $this->container->get('language_manager'));
+    $module_handler = $this->container->get('module_handler');
+
+    // Create the processors.
+    $alias_processor = new PathProcessorAlias($alias_manager);
+    $decode_processor = new PathProcessorDecode();
+    $front_processor = new PathProcessorFront($this->container->get('config.factory'));
+    $language_processor = new PathProcessorLanguage($module_handler);
+
+    // Add a url alias for testing the alias-based processor.
+    $path_crud = new Path($connection, $alias_manager);
+    $path_crud->save('user/1', 'foo');
+
+    // Add a language for testing the language-based processor.
+    $module_handler->setModuleList(array('language' => 'core/modules/language/language.module'));
+    $module_handler->load('language');
+    $language = new \stdClass();
+    $language->langcode = 'fr';
+    $language->name = 'French';
+    language_save($language);
+
+    // First, test the processor manager with the processors in the incorrect
+    // order. The alias processor will run before the language processor, meaning
+    // aliases will not be found.
+    $priorities = array(
+      1000 => $alias_processor,
+      500 => $decode_processor,
+      300 => $front_processor,
+      200 => $language_processor,
+    );
+
+    // Create the processor manager and add the processors.
+    $processor_manager = new PathProcessorManager();
+    foreach ($priorities as $priority => $processor) {
+      $processor_manager->addInbound($processor, $priority);
+    }
+
+    // Test resolving the French homepage using the incorrect processor order.
+    $test_path = 'fr';
+    $request = Request::create($test_path);
+    $processed = $processor_manager->processInbound($test_path, $request);
+    $this->assertEqual($processed, '', 'Processing in the incorrect order fails to resolve the system path from the empty path');
+
+    // Test resolving an existing alias using the incorrect processor order.
+    $test_path = 'fr/foo';
+    $request = Request::create($test_path);
+    $processed = $processor_manager->processInbound($test_path, $request);
+    $this->assertEqual($processed, 'foo', 'Processing in the incorrect order fails to resolve the system path from an alias');
+
+    // Now create a new processor manager and add the processors, this time in
+    // the correct order.
+    $processor_manager = new PathProcessorManager();
+    $priorities = array(
+      1000 => $decode_processor,
+      500 => $language_processor,
+      300 => $front_processor,
+      200 => $alias_processor,
+    );
+    foreach ($priorities as $priority => $processor) {
+      $processor_manager->addInbound($processor, $priority);
+    }
+
+    // Test resolving the French homepage using the correct processor order.
+    $test_path = 'fr';
+    $request = Request::create($test_path);
+    $processed = $processor_manager->processInbound($test_path, $request);
+    $this->assertEqual($processed, 'user', 'Processing in the correct order resolves the system path from the empty path.');
+
+    // Test resolving an existing alias using the correct processor order.
+    $test_path = 'fr/foo';
+    $request = Request::create($test_path);
+    $processed = $processor_manager->processInbound($test_path, $request);
+    $this->assertEqual($processed, 'user/1', 'Processing in the correct order resolves the system path from an alias.');
+  }
+
+}