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
@@ -33,30 +33,8 @@
   $themes = list_themes();
   foreach ($theme_list as $theme_key) {
     if ($themes[$theme_key]->status) {
-      $theme_breakpoints = breakpoint_get_theme_breakpoint_list($theme_key);
-      if (!empty($theme_breakpoints)) {
-        if ($breakpoint_group = _breakpoint_import_breakpoints($themes[$theme_key]->info['name'], $theme_key, Breakpoint::SOURCE_TYPE_THEME, $theme_breakpoints)) {
-          $breakpoint_group->save();
-          $uri = $breakpoint_group->uri();
-          if ($uri) {
-            $uri_options = $uri;
-            unset($uri_options['path']);
-            $uri = $uri['path'];
-          }
-          $message = t('The breakpoints from theme %theme are imported.', array(
-            '%theme' => check_plain($themes[$theme_key]->info['name']),
-          ));
-          if (module_exists('breakpoint_ui') && $uri) {
-            $message .= '<p>' . l(t('A new breakpoint group is created for theme %theme.', array(
-              '%theme' => check_plain($themes[$theme_key]->info['name']),
-            )), $uri, $uri_options);
-          }
-          drupal_set_message($message, 'status');
-        }
-      }
-
-      // Import custom groups.
-      _breakpoint_import_breakpoint_groups($theme_key, Breakpoint::SOURCE_TYPE_THEME);
+      $media_queries = breakpoint_get_theme_media_queries($theme_key);
+      _breakpoint_import_media_queries($theme_key, $themes[$theme_key]->info['name'], Breakpoint::SOURCE_TYPE_THEME, $media_queries);
     }
   }
 }
@@ -83,30 +61,8 @@
  */
 function breakpoint_modules_enabled($modules) {
   foreach ($modules as $module) {
-    $module_breakpoints = breakpoint_get_module_breakpoint_list($module);
-    if (!empty($module_breakpoints)) {
-      if ($breakpoint_group = _breakpoint_import_breakpoints($module, $module, Breakpoint::SOURCE_TYPE_MODULE, $module_breakpoints)) {
-        $breakpoint_group->save();
-        $uri = $breakpoint_group->uri();
-        if ($uri) {
-          $uri_options = $uri;
-          unset($uri_options['path']);
-          $uri = $uri['path'];
-        }
-        $message = t('The breakpoints from module %module are imported.', array(
-          '%module' => $module,
-        ));
-        if (module_exists('breakpoint_ui') && $uri) {
-          $message .= '<p>' . l(t('A new breakpoint group is created for module %module.', array(
-            '%module' => $module,
-          )), $uri, $uri_options);
-        }
-        drupal_set_message($message, 'status');
-      }
-    }
-
-    // Import custom groups.
-    _breakpoint_import_breakpoint_groups($module, Breakpoint::SOURCE_TYPE_MODULE);
+    $media_queries = breakpoint_get_module_media_queries($module);
+    _breakpoint_import_media_queries($module, $module, Breakpoint::SOURCE_TYPE_MODULE, $media_queries);
   }
 }
 
@@ -123,64 +79,41 @@
 }
 
 /**
- * Import breakpoints from theme or module.
+ * Import media queries from a theme or module and create a default group.
  *
- * @param string $label
- *   Name of the breakpoint group.
  * @param string $id
- *   Id of the breakpoint group.
+ *   Name of the breakpoint group.
+ * @param string $label
+ *   Human readable name of the breakpoint group.
  * @param string $sourceType
  *   Either Breakpoint::SOURCE_TYPE_THEME or Breakpoint::SOURCE_TYPE_MODULE.
  * @param array $media_queries
  *   Array of media queries keyed by id.
- *
- * @return Drupal\breakpoint\BreakpointGroup|false
- *   Returns the new breakpoint group if one is created.
  */
-function _breakpoint_import_breakpoints($label, $id, $source_type, $media_queries) {
+function _breakpoint_import_media_queries($id, $label, $source_type, $media_queries) {
   if (!empty($media_queries)) {
-    $weight = 0;
-    // Use the existing breakpoint group if it exists.
-    $breakpoint_group = entity_load('breakpoint_group', $source_type . '.' . $id);
-    if (!$breakpoint_group) {
-      // Build a new breakpoint group.
-      $breakpoint_group = new BreakpointGroup();
-      $breakpoint_group->id = $id;
-      $breakpoint_group->label = $label;
-      $breakpoint_group->source = $id;
-      $breakpoint_group->sourceType = $source_type;
-    }
-    else {
-      // Reset label.
-      $breakpoint_group->label = $label;
-    }
-    foreach ($media_queries as $name => $media_query) {
-      // Use the existing breakpoint if it exists.
-      $breakpoint = entity_load('breakpoint', $source_type . '.' . $id . '.' . $name);
-      if (!$breakpoint) {
-        // Build a new breakpoint.
-        $breakpoint = new Breakpoint;
-        $breakpoint->name = $name;
-        $breakpoint->label = drupal_ucfirst($name);
-        $breakpoint->mediaQuery = $media_query;
-        $breakpoint->source = $id;
-        $breakpoint->sourceType = $source_type;
-        $breakpoint->status = TRUE;
-        $breakpoint->weight = $weight++;
-        $breakpoint->save();
+    if ($breakpoint_group = BreakpointGroup::ImportMediaQueries($id, $label, $source_type, $media_queries)) {
+      $breakpoint_group->save();
+      $uri = $breakpoint_group->uri();
+      if ($uri) {
+        $uri_options = $uri;
+        unset($uri_options['path']);
+        $uri = $uri['path'];
       }
-      else {
-        // Reset name, label, weight and media query.
-        $breakpoint->name = $name;
-        $breakpoint->label = drupal_ucfirst($name);
-        $breakpoint->mediaQuery = $media_query;
-        $breakpoint->weight = $weight++;
+      $message = t('The breakpoints from %label are imported.', array(
+        '%label' => $label,
+      ));
+      if (module_exists('breakpoint_ui') && $uri) {
+        $message .= '<p>' . l(t('A new breakpoint group is created for %label.', array(
+          '%label' => $label,
+        )), $uri, $uri_options);
       }
-      $breakpoint_group->breakpoints[$breakpoint->id()] = $breakpoint;
+      drupal_set_message($message, 'status');
     }
-    return $breakpoint_group;
   }
-  return FALSE;
+
+  // Import custom groups.
+  _breakpoint_import_breakpoint_groups($id, $source_type);
 }
 
 /**
@@ -193,67 +126,14 @@
  *
  * @return boolean
  */
-function _breakpoint_import_breakpoint_groups($group_id, $source_type) {
-  $breakpoint_groups = config($group_id . '.breakpoint_groups');
+function _breakpoint_import_breakpoint_groups($source, $source_type) {
+  $breakpoint_groups = config($source . '.breakpoint_groups');
   if ($breakpoint_groups) {
     foreach ($breakpoint_groups->get() as $id => $data) {
-      // Breakpoints is mandatory.
+      // Breakpoints is mandatory, extra check since this is coming from config.
       if (isset($data['breakpoints']) && !empty($data['breakpoints'])) {
-        // Use the existing breakpoint group if it exists.
-        $breakpoint_group = entity_load('breakpoint_group', $source_type . '.' . $id);
-        if (!$breakpoint_group) {
-          $breakpoint_group = new BreakpointGroup();
-          $breakpoint_group->sourceType = $source_type;
-          $breakpoint_group->source = $group_id;
-          $breakpoint_group->id = $id;
-          if (isset($data['label']) && !empty($data['label'])) {
-            $breakpoint_group->label = $data['label'];
-          }
-          else {
-            $breakpoint_group->label = drupal_ucfirst($data['label']);
-          }
-        }
-        else {
-          // Reset label.
-          if (isset($data['label']) && !empty($data['label'])) {
-            $breakpoint_group->label = $data['label'];
-          }
-          else {
-            $breakpoint_group->label = drupal_ucfirst($data['label']);
-          }
-        }
-        foreach ($data['breakpoints'] as $breakpoint_id => $multipliers) {
-          // Check if breakpoint exists, assume short name.
-          $breakpoint = entity_load('breakpoint', $source_type . '.' . $group_id . '.' . $breakpoint_id);
-          // If the breakpoint doesn't exist, try using the full name.
-          if (!$breakpoint) {
-            $breakpoint = entity_load('breakpoint', $breakpoint_id);
-          }
-          if ($breakpoint) {
-            // Check if the multipliers are set, if not set them now.
-            if (is_array($multipliers) && !empty($multipliers)) {
-              // Check settings first.
-              $settings = breakpoint_settings();
-              $defined_multipliers = $settings->multipliers;
-              $new_multipliers = array_diff($multipliers, $defined_multipliers);
-              if (!empty($new_multipliers)) {
-                $defined_multipliers = array_merge($defined_multipliers, $new_multipliers);
-                breakpoint_settings_save_multipliers($defined_multipliers);
-              }
-
-              // Check breakpoint multipliers.
-              $multipliers = drupal_map_assoc(array_values($multipliers));
-              $new_multipliers = array_diff($multipliers, $breakpoint->multipliers);
-              if (!empty($new_multipliers)) {
-                $breakpoint->multipliers += $new_multipliers;
-                $breakpoint->save();
-              }
-            }
-
-            // Add breakpoint to group.
-            $breakpoint_group->breakpoints[$breakpoint->id()] = $breakpoint;
-            $breakpoint_group->save();
-          }
+        if ($breakpoint_group = BreakpointGroup::ImportBreakpointGroup($source, $source_type, $id, isset($data['label']) ? $data['label'] : drupal_ucfirst($data[$id]), $data['breakpoints'])) {
+          $breakpoint_group->save();
         }
       }
     }
@@ -262,6 +142,8 @@
 
 /**
  * Remove breakpoints from all disabled themes or uninstalled modules.
+ * The source type has to match the original source type, otherwise the group
+ * will not be deleted.
  *
  * @param array $ids
  *   Id's of the breakpoint group.
@@ -273,18 +155,20 @@
   $breakpoint_groups = entity_load_multiple('breakpoint_group', $ids);
   foreach ($breakpoint_groups as $breakpoint_group) {
     if ($breakpoint_group->sourceType == $source_type) {
-      // delete the default group.
+      // Delete the automatically created breakpoint group.
       $breakpoint_group->delete();
 
-      // delete all breakpoints defined by this theme/module.
+      // Get all breakpoints defined by this theme/module.
       $names = drupal_container()->get('config.storage')->listAll('breakpoint.breakpoint.' . $source_type . '.' . $breakpoint_group->id() . '.');
       $entity_info = entity_get_info('breakpoint');
 
+      // Remove the breakpoint.breakpoint part of the names, before loading.
       foreach ($names as &$name) {
         $name = drupal_substr($name, drupal_strlen($entity_info['config prefix']) + 1);
       }
       $breakpoints = entity_load_multiple('breakpoint', $names);
 
+      // Make sure we only delete breakpoints defined by this theme/module.
       foreach ($breakpoints as $breakpoint) {
         if ($breakpoint->sourceType == $source_type && $breakpoint->source = $breakpoint_group->id) {
           $breakpoint->delete();
@@ -292,10 +176,11 @@
       }
     }
   }
-  // Deletet groups defined by a module/theme even if that module/theme didn't
+
+  // Delete groups defined by a module/theme even if that module/theme didn't
   // define any breakpoints.
   foreach ($ids as $id) {
-    // delete all breakpoint groups defined by the theme or module.
+    // Delete all breakpoint groups defined by the theme or module.
     _breakpoint_delete_breakpoint_groups($id, $source_type);
   }
 }
@@ -319,32 +204,6 @@
 }
 
 /**
- * Load general settings.
- *
- * @return array
- *   array containing general breakpoint settings.
- */
-function breakpoint_settings() {
-  $config = config('breakpoint');
-  if ($config->isNew()) {
-    return FALSE;
-  }
-  return (object)$config->get();
-}
-
-/**
- * Save multipliers to settings.
- *
- * @param array $multipliers
- *   array containing multipliers.
- */
-function breakpoint_settings_save_multipliers($multipliers) {
-  $config = config('breakpoint');
-  $config->set('multipliers', $multipliers);
-  $config->save();
-}
-
-/**
  * Reload breakpoint groups as they were defined in the theme.
  *
  * @param string $theme_key
@@ -360,9 +219,9 @@
 
   $themes = list_themes();
   if (isset($themes[$theme_key]) && $themes[$theme_key]->status) {
-    $theme_breakpoints = breakpoint_get_theme_breakpoint_list($theme_key);
+    $theme_breakpoints = breakpoint_get_theme_media_queries($theme_key);
     if (!empty($theme_breakpoints)) {
-      return _breakpoint_import_breakpoints($themes[$theme_key]->info['name'], $theme_key, Breakpoint::SOURCE_TYPE_THEME, $theme_breakpoints);
+      return BreakpointGroup::ImportMediaQueries($theme_key, $themes[$theme_key]->info['name'], Breakpoint::SOURCE_TYPE_THEME, $theme_breakpoints);
     }
   }
   return FALSE;
@@ -377,7 +236,7 @@
  * @return array
  *   An array of breakpoints in the form $breakpoint['name'] = 'media query'.
  */
-function breakpoint_get_theme_breakpoint_list($theme_key) {
+function breakpoint_get_theme_media_queries($theme_key) {
   $themes = list_themes();
   if (!isset($themes[$theme_key])) {
     return array();
@@ -399,7 +258,7 @@
  * @return array
  *   An array of breakpoints in the form $breakpoint['name'] = 'media query'.
  */
-function breakpoint_get_module_breakpoint_list($module) {
+function breakpoint_get_module_media_queries($module) {
   if (!module_exists($module)) {
     return array();
   }
@@ -485,7 +344,7 @@
  * @return array
  *   An array containing breakpoint group labels indexed by their ids.
  */
-function breakpoint_group_select_options() {
+function breakpoint_group_labels() {
   $options = array();
   $breakpoint_groups = entity_load_multiple('breakpoint_group');
   foreach ($breakpoint_groups as $breakpoint_group) {
@@ -501,7 +360,7 @@
  * @return array
  *   An array containing breakpoints indexed by their ids.
  */
-function breakpoint_select_options() {
+function breakpoint_labels() {
   $options = array();
   $breakpoints = entity_load_multiple('breakpoint');
   foreach ($breakpoints as $breakpoint) {
diff -u b/core/modules/breakpoint/lib/Drupal/breakpoint/Breakpoint.php b/core/modules/breakpoint/lib/Drupal/breakpoint/Breakpoint.php
--- b/core/modules/breakpoint/lib/Drupal/breakpoint/Breakpoint.php
+++ b/core/modules/breakpoint/lib/Drupal/breakpoint/Breakpoint.php
@@ -8,8 +8,11 @@
 namespace Drupal\breakpoint;
 
 use Drupal\Core\Config\Entity\ConfigEntityBase;
-use Drupal\Component\Uuid\Uuid;
-use Exception;
+use Drupal\breakpoint\InvalidBreakpointException;
+use Drupal\breakpoint\InvalidBreakpointNameException;
+use Drupal\breakpoint\InvalidBreakpointSourceException;
+use Drupal\breakpoint\InvalidBreakpointSourceTypeException;
+use Drupal\breakpoint\InvalidBreakpointMediaQueryException;
 
 /**
  * Defines the Breakpoint entity.
@@ -60,6 +63,8 @@
 
   /**
    * The original media query.
+   * This is tracked separately, because a user can override a single breakpoint
+   * and reloading the media query from the theme/module is expensive.
    *
    * @var string
    */
@@ -116,10 +121,6 @@
    */
   public function __construct(array $values = array(), $entity_type = 'breakpoint') {
     parent::__construct($values, $entity_type);
-    if (!isset($this->uuid)) {
-      $uuid = new Uuid();
-      $this->uuid = $uuid->generate();
-    }
   }
 
   /**
@@ -127,20 +128,20 @@
    */
   public function save() {
     if (empty($this->id)) {
-      $this->id = $this->buildConfigName();
+      $this->id = $this->getConfigName();
     }
     if (empty($this->label)) {
       $this->label = drupal_ucfirst($this->name);
     }
 
-    // Check the media query.
+    // Check if everything is valid.
     if (!$this->isValid()) {
-      throw new Exception(t('Invalid media query detected.'));
+      throw new InvalidBreakpointException('Invalid data detected.');
     }
     // Remove ununsed multipliers.
     $this->multipliers = array_filter($this->multipliers);
 
-    // Add '1x' multiplier.
+    // Always add '1x' multiplier.
     if (!array_key_exists('1x', $this->multipliers)) {
       $this->multipliers = array('1x' => '1x') + $this->multipliers;
     }
@@ -151,44 +152,7 @@
    * Get config name.
    */
   public function getConfigName() {
-    return $this->sourceType
-      . '.' . $this->source
-      . '.' . $this->name;
-  }
-
-  /**
-   * Build config name.
-   */
-  protected function buildConfigName() {
-    // Check for illegal values in breakpoint source type.
-    if (!in_array($this->sourceType, array(
-        Breakpoint::SOURCE_TYPE_CUSTOM,
-        Breakpoint::SOURCE_TYPE_MODULE,
-        Breakpoint::SOURCE_TYPE_THEME)
-      )) {
-      throw new Exception(
-          t(
-            "Expected one of '@custom', '@module' or '@theme' for breakpoint sourceType property but got '@sourcetype'.",
-            array(
-              '@custom' => Breakpoint::SOURCE_TYPE_CUSTOM,
-              '@module' => Breakpoint::SOURCE_TYPE_MODULE,
-              '@theme' => Breakpoint::SOURCE_TYPE_THEME,
-              '@sourcetype' => $this->sourceType,
-            )
-          )
-      );
-    }
-    // Check for illegal characters in breakpoint source.
-    if (preg_match('/[^a-z_]+/', $this->source)) {
-      throw new Exception(t("Invalid value '@source' for breakpoint source property. Breakpoint source property can only contain lowercase letters and underscores.", array('@source' => $this->source)));
-    }
-    // Check for illegal characters in breakpoint names.
-    if (preg_match('/[^0-9a-z_\-]/', $this->name)) {
-      throw new Exception(t("Invalid value '@name' for breakpoint name property. Breakpoint name property can only contain lowercase alphanumeric characters, underscores (_), and hyphens (-).", array('@name' => $this->name)));
-    }
-    return $this->sourceType
-      . '.' . $this->source
-      . '.' . $this->name;
+    return $this->sourceType . '.' . $this->source . '.' . $this->name;
   }
 
   /**
@@ -222,9 +186,9 @@
    *
    */
   public function duplicate() {
-    $duplicate = new Breakpoint;
-    $duplicate->mediaQuery = $this->mediaQuery;
-    return $duplicate;
+    return entity_create('breakpoint', array(
+      'mediaQuery' => $this->mediaQuery,
+    ));
   }
 
   /**
@@ -252,11 +216,29 @@
   }
 
   /**
-   * Check if the mediaQuery is valid.
+   * Check if the breakpoint is valid.
    *
    * @see isValidMediaQuery()
    */
   public function isValid() {
+    // Check for illegal values in breakpoint source type.
+    if (!in_array($this->sourceType, array(
+        Breakpoint::SOURCE_TYPE_CUSTOM,
+        Breakpoint::SOURCE_TYPE_MODULE,
+        Breakpoint::SOURCE_TYPE_THEME)
+      )) {
+      throw new InvalidBreakpointSourceTypeException(format_string('Invalid source type @source_type', array(
+        '@source_type' => $this->sourceType,
+      )));
+    }
+    // Check for illegal characters in breakpoint source.
+    if (preg_match('/[^a-z_]+/', $this->source)) {
+      throw new InvalidBreakpointSourceException(format_string("Invalid value '@source' for breakpoint source property. Breakpoint source property can only contain lowercase letters and underscores.", array('@source' => $this->source)));
+    }
+    // Check for illegal characters in breakpoint names.
+    if (preg_match('/[^0-9a-z_\-]/', $this->name)) {
+      throw new InvalidBreakpointNameException(format_string("Invalid value '@name' for breakpoint name property. Breakpoint name property can only contain lowercase alphanumeric characters, underscores (_), and hyphens (-).", array('@name' => $this->name)));
+    }
     return $this::isValidMediaQuery($this->mediaQuery);
   }
 
@@ -317,19 +299,19 @@
             // Single expression.
             if (isset($matches[1]) && !isset($matches[2])) {
               if (!array_key_exists($matches[1], $media_features)) {
-                return FALSE;
+                throw new InvalidBreakpointMediaQueryException('Invalid media feature detected.');
               }
             }
             // Full expression.
             elseif (isset($matches[3]) && !isset($matches[4])) {
               $value = trim($matches[3]);
               if (!array_key_exists($matches[1], $media_features)) {
-                return FALSE;
+                throw new InvalidBreakpointMediaQueryException('Invalid media feature detected.');
               }
               if (is_array($media_features[$matches[1]])) {
                 // Check if value is allowed.
                 if (!array_key_exists($value, $media_features[$matches[1]])) {
-                  return FALSE;
+                  throw new InvalidBreakpointMediaQueryException('Value is not allowed.');
                 }
               }
               else {
@@ -339,15 +321,15 @@
                     if (preg_match('/^(\-)?(\d+)?((?:|em|ex|px|cm|mm|in|pt|pc|deg|rad|grad|ms|s|hz|khz|dpi|dpcm))$/i', trim($value), $length_matches)) {
                       // Only -0 is allowed.
                       if ($length_matches[1] === '-' && $length_matches[2] !== '0') {
-                        return FALSE;
+                        throw new InvalidBreakpointMediaQueryException('Invalid length detected.');
                       }
                       // If there's a unit, a number is needed as well.
                       if ($length_matches[2] === '' && $length_matches[3] !== '') {
-                        return FALSE;
+                        throw new InvalidBreakpointMediaQueryException('Unit found, value is missing.');
                       }
                     }
                     else {
-                      return FALSE;
+                      throw new InvalidBreakpointMediaQueryException('Invalid unit detected.');
                     }
                     break;
                 }
@@ -359,16 +341,16 @@
           elseif (preg_match('/^((?:only|not)?\s?)([\w\-]+)$/i', trim($query_part), $matches)) {
             if ($media_type_found) {
-              return FALSE;
+              throw new InvalidBreakpointMediaQueryException('Only one media type is allowed.');
             }
             $media_type_found = TRUE;
           }
           else {
-            return FALSE;
+            throw new InvalidBreakpointMediaQueryException('Invalid media query detected.');
           }
         }
       }
       return TRUE;
     }
-    return FALSE;
+    throw new InvalidBreakpointMediaQueryException('Media query is empty.');
   }
 }
diff -u b/core/modules/breakpoint/lib/Drupal/breakpoint/BreakpointGroup.php b/core/modules/breakpoint/lib/Drupal/breakpoint/BreakpointGroup.php
--- b/core/modules/breakpoint/lib/Drupal/breakpoint/BreakpointGroup.php
+++ b/core/modules/breakpoint/lib/Drupal/breakpoint/BreakpointGroup.php
@@ -8,7 +8,8 @@
 namespace Drupal\breakpoint;
 
 use Drupal\Core\Config\Entity\ConfigEntityBase;
-use Drupal\Component\Uuid\Uuid;
+use Drupal\breakpoint\InvalidBreakpointSourceException;
+use Drupal\breakpoint\InvalidBreakpointSourceTypeException;
 
 /**
  * Defines the BreakpointGroup entity.
@@ -78,11 +79,6 @@
    */
   public function __construct(array $values = array(), $entity_type = 'breakpoint_group') {
     parent::__construct($values, $entity_type);
-    // Assign a new UUID if there is none yet.
-    if (!isset($this->uuid)) {
-      $uuid = new Uuid();
-      $this->uuid = $uuid->generate();
-    }
     $this->loadAllBreakpoints();
   }
 
@@ -90,6 +86,10 @@
    * Overrides Drupal\Core\Entity::save().
    */
   public function save() {
+    // Check if everything is valid.
+    if (!$this->isValid()) {
+      throw new Exception('Invalid data detected.');
+    }
     // Only save the keys, but return the full objects.
     $this->breakpoints = array_keys($this->breakpoints);
     parent::save();
@@ -97,6 +97,27 @@
   }
 
   /**
+   * Check if the breakpoint group is valid.
+   */
+  public function isValid() {
+    // Check for illegal values in breakpoint group source type.
+    if (!in_array($this->sourceType, array(
+        Breakpoint::SOURCE_TYPE_CUSTOM,
+        Breakpoint::SOURCE_TYPE_MODULE,
+        Breakpoint::SOURCE_TYPE_THEME)
+      )) {
+      throw new InvalidBreakpointSourceTypeException(format_string('Invalid source type @source_type', array(
+        '@source_type' => $this->sourceType,
+      )));
+    }
+    // Check for illegal characters in breakpoint source.
+    if (preg_match('/[^a-z_]+/', $this->source)) {
+      throw new InvalidBreakpointSourceException(format_string("Invalid value '@source' for breakpoint source property. Breakpoint source property can only contain lowercase letters and underscores.", array('@source' => $this->source)));
+    }
+    return TRUE;
+  }
+
+  /**
    * Override a breakpoint group.
    */
   public function override() {
@@ -143,9 +164,9 @@
    *
    */
   public function duplicate() {
-    $duplicate = new BreakpointGroup;
-    $duplicate->breakpoints = $this->breakpoints;
-    return $duplicate;
+    return entity_create('breakpoint_group', array(
+      'breakpoints' => $this->breakpoints,
+    ));
   }
 
   /**
@@ -164,6 +185,127 @@
   }
 
   /**
+   * Add a breakpoint using a name and a media query.
+   *
+   * @param string $name
+   *   The name of the breakpoint.
+   * @param string $media_query
+   *   Media query.
+   */
+  public function addBreakpointFromMediaQuery($name, $media_query) {
+    // Use the existing breakpoint if it exists.
+    $breakpoint = entity_load('breakpoint', $this->sourceType . '.' . $this->id . '.' . $name);
+    if (!$breakpoint) {
+      // Build a new breakpoint.
+      $breakpoint = entity_create('breakpoint', array(
+        'name' => $name,
+        'label' => drupal_ucfirst($name),
+        'mediaQuery' => $media_query,
+        'source' => $this->id,
+        'sourceType' => $this->sourceType,
+        'weight' => count($this->breakpoints),
+      ));
+      $breakpoint->save();
+    }
+    else {
+      // Reset name, label, weight and media query.
+      $breakpoint->name = $name;
+      $breakpoint->label = drupal_ucfirst($name);
+      $breakpoint->mediaQuery = $media_query;
+      $breakpoint->weight = count($this->breakpoints);
+    }
+    $this->breakpoints[$breakpoint->id()] = $breakpoint;
+  }
+
+  /**
+   * Load breakpoints from a theme/module and build a default group.
+   *
+   * @param string $id
+   *   Name of the breakpoint group.
+   * @param string $label
+   *   Human readable name of the breakpoint group.
+   * @param string $sourceType
+   *   Either Breakpoint::SOURCE_TYPE_THEME or Breakpoint::SOURCE_TYPE_MODULE.
+   * @param array $media_queries
+   *   Array of media queries keyed by id.
+   *
+   * @return \Drupal\breakpoint\BreakpointGroup|false
+   *   Return the new breakpoint group containing all breakpoints.
+   */
+  public static function ImportMediaQueries($id, $label, $source_type, $media_queries) {
+    $breakpoint_group = entity_load('breakpoint_group', $source_type . '.' . $id);
+    /* @var $breakpoint_group \Drupal\breakpoint\BreakpointGroup */
+    if (!$breakpoint_group) {
+      // Build a new breakpoint group.
+      $breakpoint_group = entity_create('breakpoint_group', array(
+        'id' => $id,
+        'label' => $label,
+        'source' => $id,
+        'sourceType' => $source_type,
+      ));
+    }
+    else {
+      // Reset label.
+      $breakpoint_group->label = $label;
+    }
+
+    foreach ($media_queries as $name => $media_query) {
+      $breakpoint_group->addBreakpointFromMediaQuery($name, $media_query);
+    }
+    return $breakpoint_group;
+  }
+
+  /**
+   * Import breakpoint groups from theme or module.
+   *
+   * @param string $source
+   *   Source of the breakpoint group, theme_key or module name.
+   * @param string $sourceType
+   *   Either Breakpoint::SOURCE_TYPE_THEME or Breakpoint::SOURCE_TYPE_MODULE.
+   * @param string $name
+   *   Name of the breakpoint group.
+   * @param string $label
+   *   Human readable name of the breakpoint group.
+   * @param array $breakpoints
+   *   Array of breakpoints, using either the short name or the full name.
+   *
+   * @return \Drupal\breakpoint\BreakpointGroup|false
+   *   Return the new breakpoint group containing all breakpoints.
+   */
+  public static function ImportBreakpointGroup($source, $source_type, $name, $label, $breakpoints) {
+    // Use the existing breakpoint group if it exists.
+    $breakpoint_group = entity_load('breakpoint_group', $source_type . '.' . $name);
+    /* @var $breakpoint_group \Drupal\breakpoint\BreakpointGroup */
+    if (!$breakpoint_group) {
+      $breakpoint_group = entity_create('breakpoint_group', array(
+        'id' => $name,
+        'label' => !empty($label) ? $label : $name,
+        'source' => $source,
+        'sourceType' => $source_type,
+      ));
+    }
+    else {
+      // Reset label.
+      $breakpoint_group->label = !empty($label) ? $label : $name;
+    }
+
+    // Add breakpoints to the group.
+    foreach ($breakpoints as $breakpoint_name) {
+      // Check if breakpoint exists, assume short name.
+      $breakpoint = entity_load('breakpoint', $source_type . '.' . $source . '.' . $breakpoint_name);
+      // If the breakpoint doesn't exist, try using the full name.
+      if (!$breakpoint) {
+        $breakpoint = entity_load('breakpoint', $breakpoint_name);
+      }
+      if ($breakpoint) {
+        // Add breakpoint to group.
+        $breakpoint_group->breakpoints[$breakpoint->id()] = $breakpoint;
+      }
+    }
+    return $breakpoint_group;
+  }
+
+  /**
    * Load all breakpoints, remove non-existing ones.
    */
   protected function loadAllBreakpoints() {
reverted:
--- b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointApiTest.php
+++ /dev/null
@@ -1,90 +0,0 @@
-<?php
-/**
- * @file
- * Definition of Drupal\breakpoint\Tests\BreakpointsApiTest.
- */
-
-namespace Drupal\breakpoint\Tests;
-
-use Drupal\breakpoint\Tests\BreakpointsTestBase;
-use Drupal\breakpoint\Breakpoint;
-use Exception;
-
-/**
- * Tests for general breakpoint api functions.
- */
-class BreakpointApiTest extends BreakpointTestBase {
-
-  /**
-   * Drupal\simpletest\WebTestBase\getInfo().
-   */
-  public static function getInfo() {
-    return array(
-      'name' => 'Breakpoint general API functions',
-      'description' => 'Test general API functions of the breakpoint module.',
-      'group' => 'Breakpoint',
-    );
-  }
-
-  /**
-   * Test Breakpoint::buildConfigName().
-   */
-  public function testConfigName() {
-    $breakpoint = new Breakpoint(
-      array(
-        'label' => drupal_strtolower($this->randomName()),
-        'source' => 'custom_module',
-        // Try an invalid sourceType.
-        'sourceType' => 'oops',
-      )
-    );
-
-    try {
-      $breakpoint->save();
-    }
-    catch (Exception $e) {
-      $exception = TRUE;
-    }
-    $this->assertTrue($exception, t('breakpoint_config_name: An exception is thrown when an invalid sourceType is entered.'));
-    $this->assertEqual((string) $breakpoint->id(), '', t('breakpoint_config_name: No id is set when an invalid sourceType is entered.'));
-
-    // Try an invalid source.
-    $breakpoint->sourceType = Breakpoint::SOURCE_TYPE_CUSTOM;
-    $breakpoint->source = 'custom*_module source';
-    $exception = FALSE;
-    try {
-      $breakpoint->save();
-    }
-    catch (Exception $e) {
-      $exception = TRUE;
-    }
-    $this->assertTrue($exception, t('breakpoint_config_name: An exception is thrown when an invalid source is entered.'));
-    $this->assertEqual((string) $breakpoint->id(), '', t('breakpoint_config_name: No id is set when an invalid sourceType is entered.'));
-
-    // Try an invalid name (make sure there is at least once capital letter).
-    $breakpoint->source = 'custom_module';
-    $breakpoint->name = drupal_ucfirst($this->randomName());
-    $exception = FALSE;
-    try {
-      $breakpoint->save();
-    }
-    catch (Exception $e) {
-      $exception = TRUE;
-    }
-    $this->assertTrue($exception, t('breakpoint_config_name: An exception is thrown when an invalid name is entered.'));
-    $this->assertEqual((string) $breakpoint->id(), '', t('breakpoint_config_name: No id is set when an invalid sourceType is entered.'));
-
-    // Try a valid breakpoint.
-    $breakpoint->name = drupal_strtolower($this->randomName());
-    $breakpoint->mediaQuery = 'all';
-    $exception = FALSE;
-    try {
-      $breakpoint->save();
-    }
-    catch (Exception $e) {
-      $exception = TRUE;
-    }
-    $this->assertFalse($exception, t('breakpoint_config_name: No exception is thrown when a valid breakpoint is passed.'));
-    $this->assertEqual($breakpoint->id(), Breakpoint::SOURCE_TYPE_CUSTOM . '.custom_module.' . $breakpoint->name, t('breakpoint_config_name: A id is set when a valid breakpoint is passed.'));
-  }
-}
diff -u b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointCrudTest.php b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointCrudTest.php
--- b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointCrudTest.php
+++ b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointCrudTest.php
@@ -30,12 +30,10 @@
    */
   public function testBreakpointCrud() {
     // Add a breakpoint with minimum data only.
-    $values = array(
+    $breakpoint = entity_create('breakpoint', array(
       'label' => drupal_strtolower($this->randomName()),
       'mediaQuery' => '(min-width: 600px)',
-    );
-
-    $breakpoint = new Breakpoint($values);
+    ));
     $breakpoint->save();
 
     $this->verifyBreakpoint($breakpoint);
diff -u b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointGroupCrudTest.php b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointGroupCrudTest.php
--- b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointGroupCrudTest.php
+++ b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointGroupCrudTest.php
@@ -34,23 +34,21 @@
     $breakpoints = array();
     for ($i = 0; $i <= 3; $i++) {
       $width = ($i + 1) * 200;
-      $values = array(
+      $breakpoint = entity_create('breakpoint', array(
         'name' => drupal_strtolower($this->randomName()),
         'weight' => $i,
         'mediaQuery' => "(min-width: {$width}px)",
-      );
-      $breakpoint = new Breakpoint($values);
+      ));
       $breakpoint->save();
       $breakpoints[$breakpoint->id()] = $breakpoint;
     }
     // Add a breakpoint group with minimum data only.
     $label = $this->randomName();
-    $values = array(
+
+    $group = entity_create('breakpoint_group', array(
       'label' => $label,
       'id' => drupal_strtolower($label),
-    );
-
-    $group = new BreakpointGroup($values);
+    ));
     $group->save();
     $this->verifyBreakpointGroup($group);
 
@@ -60,8 +58,9 @@
     $this->verifyBreakpointGroup($group);
 
     // Duplicate the breakpoint group.
-    $new_set = new BreakpointGroup();
-    $new_set->breakpoints = $group->breakpoints;
+    $new_set = entity_create('breakpoint_group', array(
+      'breakpoints' => $group->breakpoints,
+    ));
     $duplicated_set = $group->duplicate();
     $this->verifyBreakpointGroup($duplicated_set, $new_set);
 
diff -u b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointMediaQueryTest.php b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointMediaQueryTest.php
--- b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointMediaQueryTest.php
+++ b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointMediaQueryTest.php
@@ -8,7 +8,7 @@
 
 use Drupal\simpletest\UnitTestBase;
 use Drupal\breakpoint\Breakpoint;
-use Exception;
+use Drupal\breakpoint\InvalidBreakpointMediaQueryException;
 
 /**
  * Tests for media queries in a breakpoint.
@@ -63,7 +63,7 @@
       try {
         $this->assertTrue(Breakpoint::isValidMediaQuery($media_query), $media_query . ' is valid.');
       }
-      catch (Exception $e) {
+      catch (InvalidBreakpointMediaQueryException $e) {
         $this->assertTrue(FALSE, $media_query . ' is valid.');
       }
     }
@@ -74,6 +74,7 @@
    */
   public function testInvalidMediaQueries() {
     $media_queries = array(
+      '',
       'not (orientation)',
       'only (orientation)',
       'all and not all',
@@ -117,7 +118,7 @@
       try {
         $this->assertFalse(Breakpoint::isValidMediaQuery($media_query), $media_query . ' is not valid.');
       }
-      catch (Exception $e) {
+      catch (InvalidBreakpointMediaQueryException $e) {
         $this->assertTrue(TRUE, $media_query . ' is not valid.');
       }
     }
diff -u b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointThemeTest.php b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointThemeTest.php
--- b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointThemeTest.php
+++ b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointThemeTest.php
@@ -27,7 +27,7 @@
    */
   public static function getInfo() {
     return array(
-      'name' => 'Breakpoint Theme functionality',
+      'name' => 'Breakpoint theme functionality',
       'description' => 'Thoroughly test the breakpoints provided by a theme.',
       'group' => 'Breakpoint',
     );
@@ -46,17 +46,18 @@
    */
   public function testThemeBreakpoints() {
     // Verify the breakpoint group for breakpoint_test_theme was created.
-    $breakpoint_group_obj = new BreakpointGroup();
-    $breakpoint_group_obj->label = 'Breakpoint test theme';
-    $breakpoint_group_obj->id = 'breakpoint_test_theme';
-    $breakpoint_group_obj->sourceType = Breakpoint::SOURCE_TYPE_THEME;
+    $breakpoint_group_obj = entity_create('breakpoint_group', array(
+      'label' => 'Breakpoint test theme',
+      'id' => 'breakpoint_test_theme',
+      'sourceType' => Breakpoint::SOURCE_TYPE_THEME,
+      'overridden' => FALSE,
+    ));
     $breakpoint_group_obj->breakpoints = array(
       'theme.breakpoint_test_theme.mobile' => array(),
       'theme.breakpoint_test_theme.narrow' => array(),
       'theme.breakpoint_test_theme.wide' => array(),
       'theme.breakpoint_test_theme.tv' => array(),
     );
-    $breakpoint_group_obj->overridden = 0;
 
     // Verify we can load this breakpoint defined by the theme.
     $this->verifyBreakpointGroup($breakpoint_group_obj);
@@ -93,17 +94,18 @@
    */
   public function testThemeBreakpointGroup() {
     // Verify the breakpoint group 'test' was created by breakpoint_test_theme.
-    $breakpoint_group_obj = new BreakpointGroup();
-    $breakpoint_group_obj->label = 'Test';
-    $breakpoint_group_obj->id = 'test';
-    $breakpoint_group_obj->sourceType = Breakpoint::SOURCE_TYPE_THEME;
-    $breakpoint_group_obj->source = 'breakpoint_test_theme';
+    $breakpoint_group_obj = entity_create('breakpoint_group', array(
+      'label' => 'Test',
+      'id' => 'test',
+      'sourceType' => Breakpoint::SOURCE_TYPE_THEME,
+      'source' => 'breakpoint_test_theme',
+      'overridden' => FALSE,
+    ));
     $breakpoint_group_obj->breakpoints = array(
       'theme.breakpoint_test_theme.mobile' => array('1.5x', '2.x'),
       'theme.breakpoint_test_theme.narrow' => array(),
       'theme.breakpoint_test_theme.wide' => array(),
     );
-    $breakpoint_group_obj->overridden = 0;
 
     // Verify we can load this breakpoint defined by the theme.
     $this->verifyBreakpointGroup($breakpoint_group_obj);
@@ -123,32 +125,22 @@
 
     // Verify the breakpoint group 'module_test' was created by
     // breakpoint_theme_test module.
-    $breakpoint_group_obj = new BreakpointGroup();
-    $breakpoint_group_obj->label = 'Test Module';
-    $breakpoint_group_obj->id = 'module_test';
-    $breakpoint_group_obj->sourceType = Breakpoint::SOURCE_TYPE_MODULE;
-    $breakpoint_group_obj->source = 'breakpoint_theme_test';
+    $breakpoint_group_obj = entity_create('breakpoint_group', array(
+      'label' => 'Test Module',
+      'id' => 'module_test',
+      'sourceType' => Breakpoint::SOURCE_TYPE_MODULE,
+      'source' => 'breakpoint_theme_test',
+      'overridden' => FALSE,
+    ));
     $breakpoint_group_obj->breakpoints = array(
       'theme.breakpoint_test_theme.mobile' => array(),
-      'theme.breakpoint_test_theme.narrow' => array('3.x', '4.x'),
+      'theme.breakpoint_test_theme.narrow' => array(),
       'theme.breakpoint_test_theme.wide' => array(),
     );
-    $breakpoint_group_obj->overridden = 0;
 
     // Verify we can load this breakpoint defined by the theme.
     $this->verifyBreakpointGroup($breakpoint_group_obj);
 
-    // Check that the multipliers are added to the settings.
-    $settings = breakpoint_settings();
-    $expected_settings = array(
-      0 => '1x',
-      1 => '1.5x',
-      2 => '2x',
-      3 => '3x',
-      4 => '4x',
-    );
-    $this->assertEqual($settings->multipliers, $expected_settings, 'Multipliers are added to settings.');
-
     // Disable the test theme and verify the breakpoint group still exists.
     theme_disable(array('breakpoint_test_theme'));
     $this->assertTrue(entity_load('breakpoint_group', 'module_test'), 'Breakpoint group still exists if theme is disabled.');
diff -u b/core/modules/breakpoint/tests/config/breakpoint_theme_test.breakpoint_groups.yml b/core/modules/breakpoint/tests/config/breakpoint_theme_test.breakpoint_groups.yml
--- b/core/modules/breakpoint/tests/config/breakpoint_theme_test.breakpoint_groups.yml
+++ b/core/modules/breakpoint/tests/config/breakpoint_theme_test.breakpoint_groups.yml
@@ -4,3 +4,3 @@
-    theme.breakpoint_test_theme.mobile: []
-    theme.breakpoint_test_theme.narrow: ['3x', '4x']
-    theme.breakpoint_test_theme.wide:
+    - theme.breakpoint_test_theme.mobile
+    - theme.breakpoint_test_theme.narrow
+    - theme.breakpoint_test_theme.wide
diff -u b/core/modules/breakpoint/tests/themes/breakpoint_test_theme/breakpoint_test_theme.info b/core/modules/breakpoint/tests/themes/breakpoint_test_theme/breakpoint_test_theme.info
--- b/core/modules/breakpoint/tests/themes/breakpoint_test_theme/breakpoint_test_theme.info
+++ b/core/modules/breakpoint/tests/themes/breakpoint_test_theme/breakpoint_test_theme.info
@@ -5 +5 @@
-hidden = FALSE
+hidden = TRUE
diff -u b/core/modules/breakpoint/tests/themes/breakpoint_test_theme/config/breakpoint_test_theme.breakpoint_groups.yml b/core/modules/breakpoint/tests/themes/breakpoint_test_theme/config/breakpoint_test_theme.breakpoint_groups.yml
--- b/core/modules/breakpoint/tests/themes/breakpoint_test_theme/config/breakpoint_test_theme.breakpoint_groups.yml
+++ b/core/modules/breakpoint/tests/themes/breakpoint_test_theme/config/breakpoint_test_theme.breakpoint_groups.yml
@@ -4,3 +4,3 @@
-    mobile: ['1.5x', '2x']
-    narrow:
-    wide:
+    - mobile
+    - narrow
+    - wide
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/breakpoint/lib/Drupal/breakpoint/InvalidBreakpointException.php
@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\breakpoint\InvalidBreakpointException.
+ */
+
+namespace Drupal\breakpoint;
+
+use RuntimeException;
+
+/**
+ * Base exception for breakpoint exception.
+ */
+class InvalidBreakpointException extends RuntimeException {}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/breakpoint/lib/Drupal/breakpoint/InvalidBreakpointMediaQueryException.php
@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\breakpoint\InvalidBreakpointMediaQueryException.
+ */
+
+namespace Drupal\breakpoint;
+
+use Drupal\breakpoint\InvalidBreakpointException;
+
+/**
+ * Exception thrown if an illegal media query is detected.
+ */
+class InvalidBreakpointMediaQueryException extends InvalidBreakpointException {}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/breakpoint/lib/Drupal/breakpoint/InvalidBreakpointNameException.php
@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\breakpoint\InvalidBreakpointNameException.
+ */
+
+namespace Drupal\breakpoint;
+
+use Drupal\breakpoint\InvalidBreakpointException;
+
+/**
+ * Exception thrown if an invalid name is detected.
+ */
+class InvalidBreakpointNameException extends InvalidBreakpointException {}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/breakpoint/lib/Drupal/breakpoint/InvalidBreakpointSourceException.php
@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\breakpoint\InvalidBreakpointSourceException.
+ */
+
+namespace Drupal\breakpoint;
+
+use Drupal\breakpoint\InvalidBreakpointException;
+
+/**
+ * Exception thrown if an invalid source is detected.
+ */
+class InvalidBreakpointSourceException extends InvalidBreakpointException {}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/breakpoint/lib/Drupal/breakpoint/InvalidBreakpointSourceTypeException.php
@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * @file
+ * Definition of Drupal\breakpoint\InvalidBreakpointSourceTypeException.
+ */
+
+namespace Drupal\breakpoint;
+
+use Drupal\breakpoint\InvalidBreakpointException;
+
+/**
+ * Exception thrown if an invalid source_type is detected.
+ */
+class InvalidBreakpointSourceTypeException extends InvalidBreakpointException {}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointAPITest.php
@@ -0,0 +1,94 @@
+<?php
+/**
+ * @file
+ * Definition of Drupal\breakpoint\Tests\BreakpointAPITest.
+ */
+
+namespace Drupal\breakpoint\Tests;
+
+use Drupal\breakpoint\Tests\BreakpointsTestBase;
+use Drupal\breakpoint\Breakpoint;
+use Drupal\breakpoint\InvalidBreakpointNameException;
+use Drupal\breakpoint\InvalidBreakpointSourceException;
+use Drupal\breakpoint\InvalidBreakpointSourceTypeException;
+
+/**
+ * Tests for general breakpoint API functions.
+ */
+class BreakpointAPITest extends BreakpointTestBase {
+
+  /**
+   * Drupal\simpletest\WebTestBase\getInfo().
+   */
+  public static function getInfo() {
+    return array(
+      'name' => 'Breakpoint general API functions',
+      'description' => 'Test general API functions of the breakpoint module.',
+      'group' => 'Breakpoint',
+    );
+  }
+
+  /**
+   * Test Breakpoint::buildConfigName().
+   */
+  public function testConfigName() {
+    // Try an invalid sourceType.
+    $breakpoint = entity_create('breakpoint', array(
+      'label' => drupal_strtolower($this->randomName()),
+      'source' => 'custom_module',
+      'sourceType' => 'oops',
+    ));
+
+    $exception = FALSE;
+    try {
+      $breakpoint->save();
+    }
+    catch (InvalidBreakpointSourceTypeException $e) {
+      $exception = TRUE;
+    }
+    $this->assertTrue($exception, t('breakpoint_config_name: An exception is thrown when an invalid sourceType is entered.'));
+
+    // Try an invalid source.
+    $breakpoint->id = '';
+    $breakpoint->sourceType = Breakpoint::SOURCE_TYPE_CUSTOM;
+    $breakpoint->source = 'custom*_module source';
+
+    $exception = FALSE;
+    try {
+      $breakpoint->save();
+    }
+    catch (InvalidBreakpointSourceException $e) {
+      $exception = TRUE;
+    }
+    $this->assertTrue($exception, t('breakpoint_config_name: An exception is thrown when an invalid source is entered.'));
+
+    // Try an invalid name (make sure there is at least once capital letter).
+    $breakpoint->id = '';
+    $breakpoint->source = 'custom_module';
+    $breakpoint->name = drupal_ucfirst($this->randomName());
+
+    $exception = FALSE;
+    try {
+      $breakpoint->save();
+    }
+    catch (InvalidBreakpointNameException $e) {
+      $exception = TRUE;
+    }
+    $this->assertTrue($exception, t('breakpoint_config_name: An exception is thrown when an invalid name is entered.'));
+
+    // Try a valid breakpoint.
+    $breakpoint->id = '';
+    $breakpoint->name = drupal_strtolower($this->randomName());
+    $breakpoint->mediaQuery = 'all';
+    
+    $exception = FALSE;
+    try {
+      $breakpoint->save();
+    }
+    catch (\Exception $e) {
+      $exception = TRUE;
+    }
+    $this->assertFalse($exception, t('breakpoint_config_name: No exception is thrown when a valid breakpoint is passed.'));
+    $this->assertEqual($breakpoint->id(), Breakpoint::SOURCE_TYPE_CUSTOM . '.custom_module.' . $breakpoint->name, t('breakpoint_config_name: A id is set when a valid breakpoint is passed.'));
+  }
+}
only in patch2:
unchanged:
--- /dev/null
+++ b/core/modules/breakpoint/lib/Drupal/breakpoint/Tests/BreakpointGroupAPITest.php
@@ -0,0 +1,79 @@
+<?php
+/**
+ * @file
+ * Definition of Drupal\breakpoint\Tests\BreakpointGroupAPITest.
+ */
+
+namespace Drupal\breakpoint\Tests;
+
+use Drupal\breakpoint\Tests\BreakpointsTestBase;
+use Drupal\breakpoint\BreakpointGroup;
+use Drupal\breakpoint\Breakpoint;
+use Drupal\breakpoint\InvalidBreakpointNameException;
+use Drupal\breakpoint\InvalidBreakpointSourceException;
+use Drupal\breakpoint\InvalidBreakpointSourceTypeException;
+
+/**
+ * Tests for general breakpoint group API functions.
+ */
+class BreakpointGroupAPITest extends BreakpointGroupTestBase {
+
+  /**
+   * Drupal\simpletest\WebTestBase\getInfo().
+   */
+  public static function getInfo() {
+    return array(
+      'name' => 'Breakpoint group general API functions',
+      'description' => 'Test general API functions of the breakpoint module.',
+      'group' => 'Breakpoint',
+    );
+  }
+
+  /**
+   * Test Breakpoint::buildConfigName().
+   */
+  public function testConfigName() {
+    // Try an invalid sourceType.
+    $breakpoint_group = entity_create('breakpoint_group', array(
+      'label' => drupal_strtolower($this->randomName()),
+      'source' => 'custom_module',
+      'sourceType' => 'oops',
+    ));
+
+    $exception = FALSE;
+    try {
+      $breakpoint_group->save();
+    }
+    catch (InvalidBreakpointSourceTypeException $e) {
+      $exception = TRUE;
+    }
+    $this->assertTrue($exception, t('An exception is thrown when an invalid sourceType is entered.'));
+
+    // Try an invalid source.
+    $breakpoint_group->id = '';
+    $breakpoint_group->sourceType = Breakpoint::SOURCE_TYPE_CUSTOM;
+    $breakpoint_group->source = 'custom*_module source';
+
+    $exception = FALSE;
+    try {
+      $breakpoint_group->save();
+    }
+    catch (InvalidBreakpointSourceException $e) {
+      $exception = TRUE;
+    }
+    $this->assertTrue($exception, t('An exception is thrown when an invalid source is entered.'));
+
+    // Try a valid breakpoint_group.
+    $breakpoint_group->id = 'test';
+    $breakpoint_group->source = 'custom_module_source';
+
+    $exception = FALSE;
+    try {
+      $breakpoint_group->save();
+    }
+    catch (\Exception $e) {
+      $exception = TRUE;
+    }
+    $this->assertFalse($exception, t('No exception is thrown when a valid data is passed.'));
+  }
+}