diff --git a/core/tests/Drupal/Tests/Core/Config/ConfigTest.php b/core/tests/Drupal/Tests/Core/Config/ConfigTest.php
new file mode 100644
index 0000000..6020f97
--- /dev/null
+++ b/core/tests/Drupal/Tests/Core/Config/ConfigTest.php
@@ -0,0 +1,501 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\Core\Config\ConfigTest.
+ */
+
+namespace Drupal\Tests\Core\Config;
+
+use Drupal\Tests\UnitTestCase;
+use Drupal\Core\Config\Config;
+use Drupal\Component\Utility\String;
+
+/**
+ * Tests the Config.
+ *
+ * @coversDefaultClass \Drupal\Core\Config\Config
+ *
+ * @group Config
+ *
+ * @see \Drupal\Core\Config\Config
+ */
+class ConfigTest extends UnitTestCase {
+
+  /**
+   * Config.
+   *
+   * @var \Drupal\Core\Config\Config
+   */
+  protected $config;
+
+  /**
+   * Storage.
+   *
+   * @var \Drupal\Core\Config\StorageInterface|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $storage;
+
+  /**
+   * Event Dispatcher.
+   *
+   * @var \Symfony\Component\EventDispatcher\EventDispatcherInterface|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $eventDispatcher;
+
+  /**
+   * Typed Config.
+   *
+   * @var \Drupal\Core\Config\TypedConfigManagerInterface|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $typedConfig;
+
+  public function setUp() {
+    $this->storage = $this->getMock('Drupal\Core\Config\StorageInterface');
+    $this->eventDispatcher = $this->getMock('Symfony\Component\EventDispatcher\EventDispatcherInterface');
+    $this->typedConfig = $this->getMock('\Drupal\Core\Config\TypedConfigManagerInterface');
+    $this->config = new Config('config.test', $this->storage, $this->eventDispatcher, $this->typedConfig);
+  }
+
+  /**
+   * Checks that the config name is set correctly.
+   *
+   * @covers ::setName
+   * @dataProvider setNameProvider
+   */
+  public function testSetName($name) {
+    // Set the name.
+    $this->config->setName($name);
+
+    // Check that the name has been set correctly.
+    $this->assertEquals($name, $this->config->getName());
+
+    // Check that the name validates.
+    // Should throw \Drupal\Core\Config\ConfigNameException if invalid.
+    $this->config->validateName($name);
+  }
+
+  /**
+   * Provides config names to test.
+   */
+  public function setNameProvider() {
+    return array(
+      // Valid name with dot.
+      array(
+        'test.name',
+      ),
+      // Maximum length.
+      array(
+        'test.' . str_repeat('a', Config::MAX_NAME_LENGTH - 5),
+      ),
+    );
+  }
+
+  /**
+   * Checks that isNew is set correctly.
+   *
+   * @covers ::isNew
+   */
+  public function testIsNew() {
+    // Config should be new by default.
+    $this->assertTrue($this->config->isNew());
+
+    // Config is no longer new once saved.
+    $this->config->save();
+    $this->assertFalse($this->config->isNew());
+  }
+
+  /**
+   * Checks that data is set correctly.
+   *
+   * @covers ::setData
+   * @dataProvider nestedDataProvider
+   */
+  public function testSetData($data) {
+    $this->config->setData($data);
+    $this->assertEquals($data, $this->config->getRawData());
+    $this->assertConfigDataEquals($data);
+  }
+
+  /**
+   * Checks that original data is set when config is saved.
+   *
+   * @covers ::save
+   * @dataProvider nestedDataProvider
+   */
+  public function testSave($data) {
+    // Set initial data.
+    $this->config->setData($data);
+
+    // Check that original data has not been set yet.
+    foreach ($data as $key => $value) {
+      $this->assertNull($this->config->getOriginal($key, FALSE));
+    }
+
+    // Save so that the original data is set.
+    $config = $this->config->save();
+
+    // Check that returned $config is instance of Config.
+    $this->assertInstanceOf('\Drupal\Core\Config\Config', $config);
+
+    // Check that the original data it saved.
+    $this->assertOriginalConfigDataEquals($data, TRUE);
+  }
+
+  /**
+   * Checks that overrides are returned by get method and original data is maintained.
+   *
+   * @covers ::setModuleOverride
+   * @covers ::setSettingsOverride
+   * @covers ::getOriginal
+   * @dataProvider overrideDataProvider
+   */
+  public function testOverrideData($data, $module_data, $setting_data) {
+    // Set initial data.
+    $this->config->setData($data);
+
+    // Check original data was set correctly.
+    $this->assertConfigDataEquals($data);
+
+    // Save so that the original data is stored.
+    $this->config->save();
+
+    // Set module override data and check value before and after save.
+    $this->config->setModuleOverride($module_data);
+    $this->assertConfigDataEquals($module_data);
+    $this->config->save();
+    $this->assertConfigDataEquals($module_data);
+
+    // Set setting override data and check value before and after save.
+    $this->config->setSettingsOverride($setting_data);
+    $this->assertConfigDataEquals($setting_data);
+    $this->config->save();
+    $this->assertConfigDataEquals($setting_data);
+
+    // Set module overrides again to ensure override order is correct.
+    $this->config->setModuleOverride($module_data);
+
+    // Setting data should be overriding module data.
+    $this->assertConfigDataEquals($setting_data);
+    $this->config->save();
+    $this->assertConfigDataEquals($setting_data);
+
+    // Check original data has not changed.
+    $this->assertOriginalConfigDataEquals($data, FALSE);
+
+    // Check setting overrides are returned with $apply_overrides = TRUE.
+    $this->assertOriginalConfigDataEquals($setting_data, TRUE);
+
+    // Check that $apply_overrides defaults to TRUE.
+    foreach ($setting_data as $key => $value) {
+      $config_value = $this->config->getOriginal($key);
+      $this->assertEquals($value, $config_value);
+    }
+  }
+
+  /**
+   * Checks that data is set correctly.
+   *
+   * @covers ::set
+   * @dataProvider nestedDataProvider
+   */
+  public function testSetValue($data) {
+    foreach ($data as $key => $value) {
+      $this->config->set($key, $value);
+    }
+    $this->assertConfigDataEquals($data);
+  }
+
+  /**
+   * Checks that exception is thrown if key in value contains a dot.
+   *
+   * @covers ::set
+   * @expectedException \Drupal\Core\Config\configValueException
+   */
+  public function testSetValidation() {
+    $this->config->set('testData', array('dot.key' => 1));
+  }
+
+  /**
+   * Checks that a single value cannot be overwritten with a nested value.
+   *
+   * @covers ::set
+   * @expectedException PHPUnit_Framework_Error_Warning
+   */
+  public function testSetIllegalOffsetValue() {
+    // Set a single value.
+    $this->config->set('testData', 1);
+
+    // Attempt to treat the single value as a nested item.
+    $this->config->set('testData.illegalOffset', 1);
+  }
+
+  /**
+   * Checks that config can be initialized with data.
+   *
+   * @covers ::initWithData
+   * @dataProvider nestedDataProvider
+   */
+  public function testInitWithData($data) {
+    $config = $this->config->initWithData($data);
+
+    // Should return the Config object.
+    $this->assertInstanceOf('\Drupal\Core\Config\Config', $config);
+
+    // Check config is not new.
+    $this->assertEquals(FALSE, $this->config->isNew());
+
+    // Check that data value was set correctly.
+    $this->assertConfigDataEquals($data);
+
+    // Check that original data was set.
+    $this->assertOriginalConfigDataEquals($data, TRUE);
+
+    // Check without applying overrides.
+    $this->assertOriginalConfigDataEquals($data, FALSE);
+  }
+
+  /**
+   * Checks clear.
+   *
+   * @covers ::clear
+   * @dataProvider simpleDataProvider
+   */
+  public function testClear($data) {
+    foreach ($data as $key => $value) {
+      // Check that values are cleared.
+      $this->config->set($key, $value);
+      $this->assertEquals($value, $this->config->get($key));
+      $this->config->clear($key);
+      $this->assertNull($this->config->get($key));
+    }
+  }
+
+  /**
+   * Checks clearing of nested data.
+   *
+   * @covers ::clear
+   * @dataProvider nestedDataProvider
+   */
+  public function testNestedClear($data) {
+    foreach ($data as $key => $value) {
+      // Check that values are cleared.
+      $this->config->set($key, $value);
+      // Check each nested value.
+      foreach($value as $nested_key => $nested_value) {
+        $full_nested_key = $key . '.' . $nested_key;
+        $this->assertEquals($nested_value, $this->config->get($full_nested_key));
+        $this->config->clear($full_nested_key);
+        $this->assertNull($this->config->get($full_nested_key));
+      }
+    }
+  }
+
+  /**
+   * Checks that config delete is working correctly.
+   *
+   * @covers ::delete
+   * @dataProvider overrideDataProvider
+   */
+  public function testDelete($data, $module_data) {
+    // Set initial data.
+    foreach ($data as $key => $value) {
+      $this->config->set($key, $value);
+    }
+    // Set overrides.
+    $this->config->setModuleOverride($module_data);
+
+    // Save.
+    $this->config->save();
+
+    // Check that original data is still correct.
+    $this->assertOriginalConfigDataEquals($data, FALSE);
+
+    // Check overrides have been set.
+    $this->assertConfigDataEquals($module_data);
+    $this->assertOriginalConfigDataEquals($module_data, TRUE);
+
+    // Check that config is new.
+    $this->assertFalse($this->config->isNew());
+
+    // Delete.
+    $this->config->delete();
+
+    // Check object properties have been reset.
+    $this->assertTrue($this->config->isNew());
+    foreach ($data as $key => $value) {
+      $this->assertEmpty($this->config->getOriginal($key, FALSE));
+    }
+
+    // Check that overrides have persisted.
+    foreach ($module_data as $key => $value) {
+      $this->assertConfigDataEquals($module_data);
+      $this->assertOriginalConfigDataEquals($module_data, TRUE);
+    }
+  }
+
+  /**
+   * Checks that data merges correctly.
+   *
+   * @covers ::merge
+   * @dataProvider mergeDataProvider
+   */
+  public function testMerge($data, $data_to_merge, $merged_data) {
+    // Set initial data.
+    $this->config->setData($data);
+
+    // Data to merge.
+    $this->config->merge($data_to_merge);
+
+    // Check that data has merged correctly.
+    $this->assertEquals($merged_data, $this->config->getRawData());
+  }
+
+  /**
+   * Provides data to test merges.
+   */
+  public function mergeDataProvider() {
+    return array(
+      array(
+        // Data.
+        array('a' => 1, 'b' => 2, 'c' => array('d' => 3)),
+        // Data to merge.
+        array('a' => 2, 'e' => 4, 'c' => array('f' => 5)),
+        // Data merged.
+        array('a' => 2, 'b' => 2, 'c' => array('d' => 3, 'f' => 5), 'e' => 4),
+      ),
+    );
+  }
+
+  /**
+   * Checks that name validation exception are thrown.
+   *
+   * @covers ::validateName
+   * @expectedException \Drupal\Core\Config\ConfigNameException
+   * @dataProvider validateNameProvider
+   */
+  public function testValidateNameException($name, $exception_message) {
+    $this->setExpectedException('\Drupal\Core\Config\ConfigNameException', $exception_message);
+    $this->config->validateName($name);
+  }
+
+  /**
+   * Provides data to test name validation.
+   */
+  public function validateNameProvider() {
+    $return = array(
+      // Name missing namespace (dot).
+      array(
+        'MissingNamespace',
+        String::format('Missing namespace in Config object name MissingNamespace.', array(
+          '@name' => 'MissingNamespace',
+        )),
+      ),
+      // Exceeds length (max length plus an extra dot).
+      array(
+        str_repeat('a', Config::MAX_NAME_LENGTH) . ".",
+        String::format('Config object name @name exceeds maximum allowed length of @length characters.', array(
+          '@name' => str_repeat('a', Config::MAX_NAME_LENGTH) . ".",
+          '@length' => Config::MAX_NAME_LENGTH,
+        )),
+      ),
+    );
+    // Name must not contain : ? * < > " ' / \
+    foreach (array(':', '?', '*', '<', '>', '"', "'", '/', '\\') as $char) {
+      $name = 'name.' . $char;
+      $return[] = array(
+        $name,
+        String::format('Invalid character in Config object name @name.', array(
+          '@name' => $name,
+        )),
+      );
+    }
+    return $return;
+  }
+
+  /**
+   * Provides override data.
+   */
+  public function overrideDataProvider() {
+    return array(
+      array(
+        // Original data.
+        array(
+          'a' => 'originalValue',
+        ),
+        // Module overrides.
+        array(
+          'a' => 'moduleValue',
+        ),
+        // Setting overrides.
+        array(
+          'a' => 'settingValue',
+        ),
+      ),
+    );
+  }
+
+  /**
+   * Provides simple test data.
+   */
+  public function simpleDataProvider() {
+    return array(
+      array(
+        array(
+          'a' => '1',
+          'b' => '2',
+          'c' => '3',
+        ),
+      ),
+    );
+  }
+
+  /**
+   * Provides nested test data.
+   */
+  public function nestedDataProvider() {
+    return array(
+      array(
+        array(
+          'a' => array(
+            'd' => 1,
+          ),
+          'b' => array(
+            'e' => 2,
+          ),
+          'c' => array(
+            'f' => 3,
+          ),
+        ),
+      ),
+    );
+  }
+
+  /**
+   * Asserts all config data equals $data provided.
+   *
+   * @param array $data
+   *   Config data to be checked.
+   */
+  public function assertConfigDataEquals($data) {
+    foreach ($data as $key => $value) {
+      $this->assertEquals($value, $this->config->get($key));
+    }
+  }
+
+  /**
+   * Asserts all original config data equals $data provided.
+   *
+   * @param array $data
+   *   Config data to be checked.
+   * @param bool $apply_overrides
+   *   Apply any overrides to the original data.
+   */
+  public function assertOriginalConfigDataEquals($data, $apply_overrides) {
+    foreach ($data as $key => $value) {
+      $config_value = $this->config->getOriginal($key, $apply_overrides);
+      $this->assertEquals($value, $config_value);
+    }
+  }
+
+}