diff -u b/core/lib/Drupal/Core/Extension/ThemeHandler.php b/core/lib/Drupal/Core/Extension/ThemeHandler.php
--- b/core/lib/Drupal/Core/Extension/ThemeHandler.php
+++ b/core/lib/Drupal/Core/Extension/ThemeHandler.php
@@ -684,2 +684,14 @@
   }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getTheme($name) {
+    $themes = $this->listInfo();
+    if (isset($themes[$name])) {
+      return $themes[$name];
+    }
+    throw new \InvalidArgumentException(sprintf('The theme %s does not exist.', $name));
+  }
+
 }
diff -u b/core/lib/Drupal/Core/Extension/ThemeHandlerInterface.php b/core/lib/Drupal/Core/Extension/ThemeHandlerInterface.php
--- b/core/lib/Drupal/Core/Extension/ThemeHandlerInterface.php
+++ b/core/lib/Drupal/Core/Extension/ThemeHandlerInterface.php
@@ -154,2 +154,16 @@
 
+  /**
+   * Returns a theme extension object from the currently active theme list.
+   *
+   * @param string $name
+   *   The name of the theme to return.
+   *
+   * @return \Drupal\Core\Extension\Extension
+   *   An extension object.
+   *
+   * @throws \InvalidArgumentException
+   *   Thrown when the requested theme does not exist.
+   */
+  public function getTheme($name);
+
 }
diff -u b/core/modules/breakpoint/breakpoint.module b/core/modules/breakpoint/breakpoint.module
--- b/core/modules/breakpoint/breakpoint.module
+++ b/core/modules/breakpoint/breakpoint.module
@@ -37,0 +38,14 @@
+
+/**
+ * Implements hook_themes_enabled()
+ */
+function breakpoint_themes_enabled($theme_list) {
+  \Drupal::service('breakpoint.manager')->clearCachedDefinitions();
+}
+
+/**
+ * Implements hook_themes_disabled()
+ */
+function breakpoint_themes_disabled($theme_list) {
+  \Drupal::service('breakpoint.manager')->clearCachedDefinitions();
+}
diff -u b/core/modules/breakpoint/src/BreakpointManager.php b/core/modules/breakpoint/src/BreakpointManager.php
--- b/core/modules/breakpoint/src/BreakpointManager.php
+++ b/core/modules/breakpoint/src/BreakpointManager.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\breakpoint;
 
+use Drupal\Core\Cache\Cache;
 use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Extension\ThemeHandlerInterface;
@@ -58,7 +59,7 @@
   protected $breakpointsByGroup;
 
   /**
-   * Constructs a new ContextualLinkManager instance.
+   * Constructs a new BreakpointManager instance.
    *
    * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
    *   The module handler.
@@ -126,23 +127,23 @@
   /**
    * {@inheritdoc}
    */
-  public function getBreakpointsByGroup($group_name) {
-    if (!isset($this->breakpointsByGroup[$group_name])) {
-      if ($cache = $this->cacheBackend->get($this->cacheKey . ':' . $group_name)) {
-        $this->breakpointsByGroup[$group_name] = $cache->data;
+  public function getBreakpointsByGroup($group) {
+    if (!isset($this->breakpointsByGroup[$group])) {
+      if ($cache = $this->cacheBackend->get($this->cacheKey . ':' . $group)) {
+        $this->breakpointsByGroup[$group] = $cache->data;
       }
       else {
         $breakpoints = array();
         foreach ($this->getDefinitions() as $plugin_id => $plugin_definition) {
-          if ($plugin_definition['group'] == $group_name) {
+          if ($plugin_definition['group'] == $group) {
             $breakpoints[$plugin_id] = $plugin_definition;
           }
         }
-        $this->cacheBackend->set($this->cacheKey . ':' . $group_name, $breakpoints);
-        $this->breakpointsByGroup[$group_name] = $breakpoints;
+        $this->cacheBackend->set($this->cacheKey . ':' . $group, $breakpoints, Cache::PERMANENT, array('breakpoints' => TRUE));
+        $this->breakpointsByGroup[$group] = $breakpoints;
       }
     }
-    return $this->breakpointsByGroup[$group_name];
+    return $this->breakpointsByGroup[$group];
   }
 
   /**
@@ -160,11 +161,41 @@
       }
     }
     asort($groups);
-    $this->cacheBackend->set($this->cacheKey . '::groups', $groups);
+    $this->cacheBackend->set($this->cacheKey . '::groups', $groups, Cache::PERMANENT, array('breakpoints' => TRUE));
     return $groups;
   }
 
   /**
+   * {@inheritdoc}
+   */
+  public function getGroupProviders($group) {
+    $providers = array();
+    $breakpoints = $this->getBreakpointsByGroup($group);
+    foreach ($breakpoints as $breakpoint) {
+      $provider = $breakpoint['provider'];
+      $extension = FALSE;
+      if ($this->moduleHandler->moduleExists($provider)) {
+        $extension = $this->moduleHandler->getModule($provider);
+      }
+      elseif ($this->themeHandler->themeExists($provider)) {
+        $extension = $this->themeHandler->getTheme($provider);
+      }
+      if ($extension) {
+        $providers[$extension->getName()] = $extension->getType();
+      }
+    }
+    return $providers;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function clearCachedDefinitions() {
+    parent::clearCachedDefinitions();
+    $this->breakpointsByGroup = NULL;
+  }
+
+  /**
    * @param string $group
    *
    * @return string
diff -u b/core/modules/breakpoint/src/BreakpointManagerInterface.php b/core/modules/breakpoint/src/BreakpointManagerInterface.php
--- b/core/modules/breakpoint/src/BreakpointManagerInterface.php
+++ b/core/modules/breakpoint/src/BreakpointManagerInterface.php
@@ -15,13 +15,13 @@
   /**
    * Gets breakpoints for the specified group.
    *
-   * @param string $group_name
+   * @param string $group
    *   The breakpoint group to retrieve.
    *
    * @return array
    *   Array of breakpoints keyed by machine name.
    */
-  public function getBreakpointsByGroup($group_name);
+  public function getBreakpointsByGroup($group);
 
   /**
    * Gets all the existing breakpoint groups.
@@ -34 +34,13 @@
-} 
\ No newline at end of file
+  /**
+   * Gets all the providers for the specified breakpoint group.
+   *
+   * @param string $group
+   *   The breakpoint group to retrieve.
+   *
+   * @return array
+   *   An array keyed by provider name with values of provider type (module or
+   *   theme).
+   */
+  public function getGroupProviders($group);
+
+}
diff -u b/core/modules/breakpoint/src/Tests/BreakpointDiscoveryTest.php b/core/modules/breakpoint/src/Tests/BreakpointDiscoveryTest.php
--- b/core/modules/breakpoint/src/Tests/BreakpointDiscoveryTest.php
+++ b/core/modules/breakpoint/src/Tests/BreakpointDiscoveryTest.php
@@ -20,99 +20,115 @@
    *
    * @var array
    */
-  public static $modules = array('breakpoint', 'breakpoints_module_test');
+  public static $modules = array('breakpoint', 'breakpoint_module_test');
 
   public function setUp() {
     parent::setUp();
-    \Drupal::service('theme_handler')->enable(array('breakpoint_test_theme'));
+    \Drupal::service('theme_handler')->enable(array('breakpoint_theme_test'));
   }
 
   /**
    * Test the breakpoint group created for a theme.
    */
   public function testThemeBreakpoints() {
-    // Verify the breakpoint group for breakpoint_test_theme was created.
+    // Verify the breakpoint group for breakpoint_theme_test was created.
     $expected_breakpoints = array(
-        'breakpoint_test_theme.mobile' => array(
+        'breakpoint_theme_test.mobile' => array(
           'label' => 'mobile',
           'mediaQuery' => '(min-width: 0px)',
           'weight' => 0,
           'multipliers' => array(
             '1x',
           ),
-          'provider' => 'breakpoint_test_theme',
-          'id' => 'breakpoint_test_theme.mobile',
-          'group' => 'breakpoint_test_theme',
+          'provider' => 'breakpoint_theme_test',
+          'id' => 'breakpoint_theme_test.mobile',
+          'group' => 'breakpoint_theme_test',
         ),
-        'breakpoint_test_theme.narrow' => array(
+        'breakpoint_theme_test.narrow' => array(
           'label' => 'narrow',
           'mediaQuery' => '(min-width: 560px)',
           'weight' => 1,
           'multipliers' => array(
             '1x',
           ),
-          'provider' => 'breakpoint_test_theme',
-          'id' => 'breakpoint_test_theme.narrow',
-          'group' => 'breakpoint_test_theme',
+          'provider' => 'breakpoint_theme_test',
+          'id' => 'breakpoint_theme_test.narrow',
+          'group' => 'breakpoint_theme_test',
         ),
-        'breakpoint_test_theme.wide' => array(
+        'breakpoint_theme_test.wide' => array(
           'label' => 'wide',
           'mediaQuery' => '(min-width: 851px)',
           'weight' => 2,
           'multipliers' => array(
             '1x',
           ),
-          'provider' => 'breakpoint_test_theme',
-          'id' => 'breakpoint_test_theme.wide',
-          'group' => 'breakpoint_test_theme',
+          'provider' => 'breakpoint_theme_test',
+          'id' => 'breakpoint_theme_test.wide',
+          'group' => 'breakpoint_theme_test',
         ),
-        'breakpoint_test_theme.tv' => array(
+        'breakpoint_theme_test.tv' => array(
           'label' => 'tv',
           'mediaQuery' => 'only screen and (min-width: 3456px)',
           'weight' => 3,
           'multipliers' => array(
             '1x',
           ),
-          'provider' => 'breakpoint_test_theme',
-          'id' => 'breakpoint_test_theme.tv',
-          'group' => 'breakpoint_test_theme',
+          'provider' => 'breakpoint_theme_test',
+          'id' => 'breakpoint_theme_test.tv',
+          'group' => 'breakpoint_theme_test',
         ),
     );
 
-    $breakpoints = \Drupal::service('breakpoint.manager')->getBreakpointsByGroup('breakpoint_test_theme');
+    $breakpoints = \Drupal::service('breakpoint.manager')->getBreakpointsByGroup('breakpoint_theme_test');
     foreach ($expected_breakpoints as $id => $expected_breakpoint) {
       $this->assertEqual($expected_breakpoint, $breakpoints[$id]);
     }
+  }
 
-    // Verify the breakpoint group for breakpoint_test_theme.group2 was created.
+  /**
+   * Test the custom breakpoint group provided by a theme and a module.
+   */
+  public function testCustomBreakpointGroups () {
+    // Verify the breakpoint group for breakpoint_theme_test.group2 was created.
     $expected_breakpoints = array(
-      'breakpoint_test_theme.group2.narrow' => array(
+      'breakpoint_theme_test.group2.narrow' => array(
         'label' => 'narrow',
         'mediaQuery' => '(min-width: 560px)',
         'weight' => 1,
         'multipliers' => array(
           '1x',
-          '2x'
+          '2x',
         ),
-        'provider' => 'breakpoint_test_theme',
-        'id' => 'breakpoint_test_theme.group2.narrow',
-        'group' => 'breakpoint_test_theme.group2',
+        'provider' => 'breakpoint_theme_test',
+        'id' => 'breakpoint_theme_test.group2.narrow',
+        'group' => 'breakpoint_theme_test.group2',
       ),
-      'breakpoint_test_theme.group2.wide' => array(
+      'breakpoint_theme_test.group2.wide' => array(
         'label' => 'wide',
         'mediaQuery' => '(min-width: 851px)',
         'weight' => 2,
         'multipliers' => array(
           '1x',
-          '2x'
+          '2x',
+        ),
+        'provider' => 'breakpoint_theme_test',
+        'id' => 'breakpoint_theme_test.group2.wide',
+        'group' => 'breakpoint_theme_test.group2',
+      ),
+      'breakpoint_module_test.breakpoint_theme_test.group2.tv' => array(
+        'label' => 'tv',
+        'mediaQuery' => '(min-width: 6000px)',
+        'weight' => 3,
+        'multipliers' => array(
+          '1x',
         ),
-        'provider' => 'breakpoint_test_theme',
-        'id' => 'breakpoint_test_theme.group2.wide',
-        'group' => 'breakpoint_test_theme.group2',
+        'provider' => 'breakpoint_module_test',
+        'id' => 'breakpoint_module_test.breakpoint_theme_test.group2.tv',
+        'group' => 'breakpoint_theme_test.group2',
       ),
     );
 
-    $breakpoints = \Drupal::service('breakpoint.manager')->getBreakpointsByGroup('breakpoint_test_theme.group2');
+    $breakpoints = \Drupal::service('breakpoint.manager')->getBreakpointsByGroup('breakpoint_theme_test.group2');
     foreach ($expected_breakpoints as $id => $expected_breakpoint) {
       $this->assertEqual($expected_breakpoint, $breakpoints[$id]);
     }
@@ -123,18 +139,18 @@
    */
   public function testModuleBreakpoints() {
     $expected_breakpoints = array(
-      'breakpoints_module_test.mobile' => array(
+      'breakpoint_module_test.mobile' => array(
         'label' => 'mobile',
         'mediaQuery' => '(min-width: 0px)',
         'weight' => 0,
         'multipliers' => array(
           '1x',
         ),
-        'provider' => 'breakpoints_module_test',
-        'id' => 'breakpoints_module_test.mobile',
-        'group' => 'breakpoints_module_test',
+        'provider' => 'breakpoint_module_test',
+        'id' => 'breakpoint_module_test.mobile',
+        'group' => 'breakpoint_module_test',
       ),
-      'breakpoints_module_test.standard' => array(
+      'breakpoint_module_test.standard' => array(
         'label' => 'standard',
         'mediaQuery' => '(min-width: 560px)',
         'weight' => 1,
@@ -142,13 +158,13 @@
           '1x',
           '2x',
         ),
-        'provider' => 'breakpoints_module_test',
-        'id' => 'breakpoints_module_test.standard',
-        'group' => 'breakpoints_module_test',
+        'provider' => 'breakpoint_module_test',
+        'id' => 'breakpoint_module_test.standard',
+        'group' => 'breakpoint_module_test',
       ),
     );
 
-    $breakpoints = \Drupal::service('breakpoint.manager')->getBreakpointsByGroup('breakpoints_module_test');
+    $breakpoints = \Drupal::service('breakpoint.manager')->getBreakpointsByGroup('breakpoint_module_test');
     foreach ($expected_breakpoints as $id => $expected_breakpoint) {
       $this->assertEqual($expected_breakpoint, $breakpoints[$id]);
     }
@@ -160,12 +176,19 @@
   public function testBreakpointGroups() {
     $expected = array(
       'bartik' => 'Bartik',
-      'breakpoints_module_test' => 'Breakpoint test module',
-      'breakpoint_test_theme' => 'Breakpoint test theme',
-      'breakpoint_test_theme.group2' => 'breakpoint_test_theme.group2',
+      'breakpoint_module_test' => 'Breakpoint test module',
+      'breakpoint_theme_test' => 'Breakpoint test theme',
+      'breakpoint_theme_test.group2' => 'breakpoint_theme_test.group2',
     );
     $breakpoint_groups = \Drupal::service('breakpoint.manager')->getGroups();
     $this->assertEqual($expected, $breakpoint_groups);
+
+    $expected = array(
+      'breakpoint_module_test' => 'module',
+      'breakpoint_theme_test' => 'theme',
+    );
+    $breakpoint_group_providers = \Drupal::service('breakpoint.manager')->getGroupProviders('breakpoint_theme_test.group2');
+    $this->assertEqual($expected, $breakpoint_group_providers);
   }
 
 }
reverted:
--- b/core/modules/breakpoint/tests/modules/breakpoints_module_test/breakpoints_module_test.breakpoints.yml
+++ /dev/null
@@ -1,12 +0,0 @@
-breakpoints_module_test.mobile:
-  label: mobile
-  mediaQuery: '(min-width: 0px)'
-  weight: 0
-  # Don't include multipliers. A 1x multiplier this will be enforced by default.
-breakpoints_module_test.standard:
-  label: standard
-  mediaQuery: '(min-width: 560px)'
-  weight: 1
-  # Don't include a 1x multiplier this will be enforced by default.
-  multipliers:
-    - 2x
reverted:
--- b/core/modules/breakpoint/tests/modules/breakpoints_module_test/breakpoints_module_test.info.yml
+++ /dev/null
@@ -1,6 +0,0 @@
-name: 'Breakpoint test module'
-type: module
-description: 'Test module for breakpoint.'
-version: VERSION
-core: 8.x
-
reverted:
--- b/core/modules/breakpoint/tests/themes/breakpoint_test_theme/breakpoint_test_theme.breakpoints.yml
+++ /dev/null
@@ -1,40 +0,0 @@
-breakpoint_test_theme.mobile:
-  label: mobile
-  mediaQuery: '(min-width: 0px)'
-  weight: 0
-  multipliers:
-    - 1x
-breakpoint_test_theme.narrow:
-  label: narrow
-  mediaQuery: '(min-width: 560px)'
-  weight: 1
-  multipliers:
-    - 1x
-breakpoint_test_theme.wide:
-  label: wide
-  mediaQuery: '(min-width: 851px)'
-  weight: 2
-  multipliers:
-    - 1x
-breakpoint_test_theme.tv:
-  label: tv
-  mediaQuery: 'only screen and (min-width: 3456px)'
-  weight: 3
-  multipliers:
-    - 1x
-breakpoint_test_theme.group2.narrow:
-  label: narrow
-  mediaQuery: '(min-width: 560px)'
-  weight: 1
-  multipliers:
-    - 1x
-    - 2x
-  group: breakpoint_test_theme.group2
-breakpoint_test_theme.group2.wide:
-  label: wide
-  mediaQuery: '(min-width: 851px)'
-  weight: 2
-  multipliers:
-    - 1x
-    - 2x
-  group: breakpoint_test_theme.group2
diff -u b/core/modules/responsive_image/src/Entity/ResponsiveImageMapping.php b/core/modules/responsive_image/src/Entity/ResponsiveImageMapping.php
--- b/core/modules/responsive_image/src/Entity/ResponsiveImageMapping.php
+++ b/core/modules/responsive_image/src/Entity/ResponsiveImageMapping.php
@@ -81,6 +81,13 @@
   /**
    * {@inheritdoc}
    */
+  public function __construct(array $values, $entity_type_id = 'responsive_image_mapping') {
+    parent::__construct($values, $entity_type_id);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function addMapping($breakpoint_id, $multiplier, $image_style) {
     foreach ($this->mappings as &$mapping) {
       if ($mapping['breakpoint_id'] === $breakpoint_id && $mapping['multiplier'] === $multiplier) {
@@ -93,6 +100,7 @@
       'multiplier' => $multiplier,
       'image_style' => $image_style,
     );
+    $this->keyedMappings = NULL;
     return $this;
   }
 
@@ -109,14 +117,8 @@
   public function getKeyedMappings() {
     if (!$this->keyedMappings) {
       $this->keyedMappings = array();
-      $valid_breakpoints = \Drupal::service('breakpoint.manager')->getBreakpointsByGroup($this->breakpointGroup);
       foreach($this->mappings as $mapping) {
-        // If the breakpoint exists and the multiplier exists.
-        // @todo think about if this is just super defensive?
-        if (isset($valid_breakpoints[$mapping['breakpoint_id']])
-          && in_array($mapping['multiplier'], $valid_breakpoints[$mapping['breakpoint_id']]['multipliers'])) {
-          $this->keyedMappings[$mapping['breakpoint_id']][$mapping['multiplier']] = $mapping['image_style'];
-        }
+        $this->keyedMappings[$mapping['breakpoint_id']][$mapping['multiplier']] = $mapping['image_style'];
       }
     }
     return $this->keyedMappings;
@@ -143,6 +145,10 @@
    * {@inheritdoc}
    */
   public function setBreakpointGroup($breakpoint_group) {
+    // If the breakpoint group is changed then the mappings are invalid.
+    if ($breakpoint_group !== $this->breakpointGroup) {
+      $this->removeMappings();
+    }
     $this->set('breakpointGroup', $breakpoint_group);
     return $this;
   }
@@ -161,5 +167,18 @@
     $this->mappings = array();
+    $this->keyedMappings = NULL;
     return $this;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function calculateDependencies() {
+    parent::calculateDependencies();
+    $providers = \Drupal::service('breakpoint.manager')->getGroupProviders($this->breakpointGroup);
+    foreach ($providers as $provider => $type) {
+      $this->addDependency($type, $provider);
+    }
+    return $this->dependencies;
+  }
+
 }
diff -u b/core/themes/seven/seven.breakpoints.yml b/core/themes/seven/seven.breakpoints.yml
--- b/core/themes/seven/seven.breakpoints.yml
+++ b/core/themes/seven/seven.breakpoints.yml
@@ -12 +12 @@
-    - 1x
\ No newline at end of file
+    - 1x
reverted:
--- b/core/themes/stark/stark.info.yml
+++ a/core/themes/stark/stark.info.yml
@@ -9,26 +9,3 @@
     - css/layout.css
 stylesheets-remove:
   - normalize.css
-
-breakpoints:
-  mobile:
-    name: mobile
-    label: mobile
-    mediaQuery: '(min-width: 0px)'
-    weight: 0
-    multipliers:
-     - 1x
-  narrow:
-    name: narrow
-    label: narrow
-    mediaQuery: 'all and (min-width: 480px) and (max-width: 959px)'
-    weight: 1
-    multipliers:
-      - 1x
-  wide:
-    name: wide
-    label: wide
-    mediaQuery: 'all and (min-width: 960px)'
-    weight: 2
-    multipliers:
-      - 1x
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/breakpoint/tests/modules/breakpoint_module_test/breakpoint_module_test.breakpoints.yml
@@ -0,0 +1,21 @@
+breakpoint_module_test.mobile:
+  label: mobile
+  mediaQuery: '(min-width: 0px)'
+  weight: 0
+  # Don't include multipliers. A 1x multiplier this will be enforced by default.
+breakpoint_module_test.standard:
+  label: standard
+  mediaQuery: '(min-width: 560px)'
+  weight: 1
+  # Don't include a 1x multiplier this will be enforced by default.
+  multipliers:
+    - 2x
+# Test providing a breakpoint for group matching the group provided by
+# breakpoint_test_theme.
+breakpoint_module_test.breakpoint_theme_test.group2.tv:
+  label: tv
+  mediaQuery: '(min-width: 6000px)'
+  weight: 3
+  multipliers:
+    - 1x
+  group: breakpoint_theme_test.group2
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/breakpoint/tests/modules/breakpoint_module_test/breakpoint_module_test.info.yml
@@ -0,0 +1,6 @@
+name: 'Breakpoint test module'
+type: module
+description: 'Test module for breakpoint.'
+version: VERSION
+core: 8.x
+
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/breakpoint/tests/themes/breakpoint_theme_test/breakpoint_theme_test.breakpoints.yml
@@ -0,0 +1,40 @@
+breakpoint_theme_test.mobile:
+  label: mobile
+  mediaQuery: '(min-width: 0px)'
+  weight: 0
+  multipliers:
+    - 1x
+breakpoint_theme_test.narrow:
+  label: narrow
+  mediaQuery: '(min-width: 560px)'
+  weight: 1
+  multipliers:
+    - 1x
+breakpoint_theme_test.wide:
+  label: wide
+  mediaQuery: '(min-width: 851px)'
+  weight: 2
+  multipliers:
+    - 1x
+breakpoint_theme_test.tv:
+  label: tv
+  mediaQuery: 'only screen and (min-width: 3456px)'
+  weight: 3
+  multipliers:
+    - 1x
+breakpoint_theme_test.group2.narrow:
+  label: narrow
+  mediaQuery: '(min-width: 560px)'
+  weight: 1
+  multipliers:
+    - 1x
+    - 2x
+  group: breakpoint_theme_test.group2
+breakpoint_theme_test.group2.wide:
+  label: wide
+  mediaQuery: '(min-width: 851px)'
+  weight: 2
+  multipliers:
+    - 1x
+    - 2x
+  group: breakpoint_theme_test.group2
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/responsive_image/tests/src/ResponsiveImageMappingConfigEntityUnitTest.php
@@ -0,0 +1,198 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\responsive_image\Tests\ResponsiveImageMappingConfigEntityUnitTest.
+ */
+
+namespace Drupal\responsive_image\Tests;
+
+use Drupal\Core\DependencyInjection\ContainerBuilder;
+use Drupal\responsive_image\Entity\ResponsiveImageMapping;
+use Drupal\Tests\UnitTestCase;
+
+/**
+ * @coversDefaultClass \Drupal\responsive_image\Entity\ResponsiveImageMapping
+ * @group block
+ */
+class ResponsiveImageMappingConfigEntityUnitTest extends UnitTestCase {
+
+  /**
+   * The entity type used for testing.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeInterface|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $entityType;
+
+  /**
+   * The entity manager used for testing.
+   *
+   * @var \Drupal\Core\Entity\EntityManagerInterface|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $entityManager;
+
+  /**
+   * The breakpoint manager used for testing.
+   *
+   * @var \Drupal\breakpoint\BreakpointManagerInterface|\PHPUnit_Framework_MockObject_MockObject
+   */
+  protected $breakpointManager;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setUp() {
+    $this->entityType = $this->getMock('\Drupal\Core\Entity\EntityTypeInterface');
+    $this->entityType->expects($this->any())
+       ->method('getProvider')
+       ->will($this->returnValue('responsive_image'));
+
+    $this->entityManager = $this->getMock('\Drupal\Core\Entity\EntityManagerInterface');
+    $this->entityManager->expects($this->any())
+      ->method('getDefinition')
+      ->with('responsive_image_mapping')
+      ->will($this->returnValue($this->entityType));
+
+    $this->breakpointManager = $this->getMock('\Drupal\breakpoint\BreakpointManagerInterface');
+
+    $container = new ContainerBuilder();
+    $container->set('entity.manager', $this->entityManager);
+    $container->set('breakpoint.manager', $this->breakpointManager);
+    \Drupal::setContainer($container);
+  }
+
+  /**
+   * @covers ::calculateDependencies
+   */
+  public function testCalculateDependencies() {
+    $entity = new ResponsiveImageMapping(array('breakpointGroup' => 'test_group'));
+    $entity->setBreakpointGroup('test_group');
+
+    $this->breakpointManager->expects($this->any())
+      ->method('getGroupProviders')
+      ->with('test_group')
+      ->willReturn(array('bartik' => 'theme', 'toolbar' => 'module'));
+
+    $dependencies = $entity->calculateDependencies();
+    $this->assertContains('toolbar', $dependencies['module']);
+    $this->assertContains('bartik', $dependencies['theme']);
+  }
+
+  /**
+   * @covers ::addMapping
+   * @covers ::hasMapping
+   */
+  public function testHasMappings() {
+    $entity = new ResponsiveImageMapping(array());
+    $this->assertFalse($entity->hasMappings());
+    $entity->addMapping('test_breakpoint', '1x', 'test_style');
+    $this->assertTrue($entity->hasMappings());
+  }
+
+  /**
+   * @covers ::addMapping
+   * @covers ::getImageStyle
+   */
+  public function testGetImageStyle() {
+    $entity = new ResponsiveImageMapping(array(''));
+    $entity->addMapping('test_breakpoint', '1x', 'test_style');
+    $this->assertEquals('test_style', $entity->getImageStyle('test_breakpoint', '1x'));
+    $this->assertNull($entity->getImageStyle('test_unknown_breakpoint', '1x'));
+  }
+
+  /**
+   * @covers ::addMapping
+   * @covers ::getMappings
+   */
+  public function testGetKeyedMappings() {
+    $entity = new ResponsiveImageMapping(array(''));
+    $entity->addMapping('test_breakpoint', '1x', 'test_style');
+    $entity->addMapping('test_breakpoint', '2x', 'test_style2');
+    $entity->addMapping('test_breakpoint2', '1x', 'test_style3');
+
+    $expected = array(
+      'test_breakpoint' => array(
+        '1x' => 'test_style',
+        '2x' => 'test_style2',
+      ),
+      'test_breakpoint2' => array(
+        '1x' => 'test_style3',
+      )
+    );
+    $this->assertEquals($expected, $entity->getKeyedMappings());
+
+    // Add another mapping to ensure keyed mapping static cache is rebuilt.
+    $entity->addMapping('test_breakpoint2', '2x', 'test_style4');
+    $expected['test_breakpoint2']['2x'] = 'test_style4';
+    $this->assertEquals($expected, $entity->getKeyedMappings());
+  }
+
+  /**
+   * @covers ::addMapping
+   * @covers ::getMappings
+   */
+  public function testGetMappings() {
+    $entity = new ResponsiveImageMapping(array(''));
+    $entity->addMapping('test_breakpoint', '1x', 'test_style');
+    $entity->addMapping('test_breakpoint', '2x', 'test_style2');
+    $entity->addMapping('test_breakpoint2', '1x', 'test_style3');
+
+    $expected = array(
+      array(
+        'breakpoint_id' => 'test_breakpoint',
+        'multiplier' => '1x',
+        'image_style' => 'test_style',
+      ),
+      array(
+        'breakpoint_id' => 'test_breakpoint',
+        'multiplier' => '2x',
+        'image_style' => 'test_style2',
+      ),
+      array(
+        'breakpoint_id' => 'test_breakpoint2',
+        'multiplier' => '1x',
+        'image_style' => 'test_style3',
+      ),
+    );
+    $this->assertEquals($expected, $entity->getMappings());
+  }
+
+  /**
+   * @covers ::addMapping
+   * @covers ::removeMappings
+   */
+  public function testRemoveMappings() {
+    $entity = new ResponsiveImageMapping(array(''));
+    $entity->addMapping('test_breakpoint', '1x', 'test_style');
+    $entity->addMapping('test_breakpoint', '2x', 'test_style2');
+    $entity->addMapping('test_breakpoint2', '1x', 'test_style3');
+
+    $this->assertTrue($entity->hasMappings());
+    $entity->removeMappings();
+    $this->assertEmpty($entity->getMappings());
+    $this->assertEmpty($entity->getKeyedMappings());
+    $this->assertFalse($entity->hasMappings());
+  }
+
+  /**
+   * @covers ::setBreakpointGroup
+   * @covers ::getBreakpointGroup
+   */
+  public function testSetBreakpointGroup() {
+    $entity = new ResponsiveImageMapping(array('breakpointGroup' => 'test_group'));
+    $entity->addMapping('test_breakpoint', '1x', 'test_style');
+    $entity->addMapping('test_breakpoint', '2x', 'test_style2');
+    $entity->addMapping('test_breakpoint2', '1x', 'test_style3');
+
+    // Ensure that setting to same group does not remove mappings.
+    $entity->setBreakpointGroup('test_group');
+    $this->assertTrue($entity->hasMappings());
+    $this->assertEquals('test_group', $entity->getBreakpointGroup());
+
+    // Ensure that changing the group removes mappings.
+    $entity->setBreakpointGroup('test_group2');
+    $this->assertEquals('test_group2', $entity->getBreakpointGroup());
+    $this->assertFalse($entity->hasMappings());
+  }
+
+}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/themes/stark/stark.breakpoints.yml
@@ -0,0 +1,18 @@
+stark.mobile:
+  label: mobile
+  mediaQuery: '(min-width: 0px)'
+  weight: 0
+  multipliers:
+   - 1x
+stark.narrow:
+  label: narrow
+  mediaQuery: 'all and (min-width: 480px) and (max-width: 959px)'
+  weight: 1
+  multipliers:
+    - 1x
+stark.wide:
+  label: wide
+  mediaQuery: 'all and (min-width: 960px)'
+  weight: 2
+  multipliers:
+    - 1x
\ No newline at end of file