statistics library is not loaded if node template doesn't print it

Right, because there's no proper tests I'll look out for bug reports.

Re #3 this this like pretty important functionality for the statistics module and probably something that should be tested. #2385243: Make core user fields available for twig templates added a test theme for a similar reason - didn't seem like too much work.

Working on it.

Great start @Denchev thanks for the work on this!

Few cosmetic comments:

1. +++ b/core/modules/statistics/src/Tests/StatisticsAttachedTest.php
   @@ -0,0 +1,63 @@
   +    // Install "block_test_theme" and set it as the default theme.
   

   s/block_test_theme/statistics_test_attached

   Copy-paste kind of thing I assume.

2. +++ b/core/modules/statistics/src/Tests/StatisticsAttachedTest.php
   @@ -0,0 +1,63 @@
   +    global $base_root;
   +    $this->assertNotIdentical(strpos($page, '<script src="' . $base_root . base_path() . 'core/modules/statistics/statistics.js'), FALSE, 'Statistics library is available');
   

   Is there a way to avoid using the global here?

   Maybe asserting just statistics.js? Something like:

   $this->assertRaw('core/modules/statistics/statistics.js')
   

3. +++ b/core/modules/statistics/tests/themes/statistics_test_attached/node.html.twig
   @@ -0,0 +1,93 @@
   + * Available variables:
   + * - node: Full node entity.
   + *   - id: The node ID.
   + *   - bundle: The type of the node, for example, "page" or "article".
   + *   - authorid: The user ID of the node author.
   + *   - createdtime: Time the node was published formatted in Unix timestamp.
   + *   - changedtime: Time the node was changed formatted in Unix timestamp.
   + * - label: The title of the node.
   + * - content: All node items. Use {{ content }} to print them all,
   + *   or print a subset such as {{ content.field_example }}. Use
   + *   {{ content|without('field_example') }} to temporarily suppress the printing
   + *   of a given child element.
   + * - author_picture: The node author user entity, rendered using the "compact"
   + *   view mode.
   + * - metadata: Metadata for this node.
   + * - date: Themed creation date field.
   + * - author_name: Themed author name field.
   + * - url: Direct URL of the current node.
   + * - display_submitted: Whether submission information should be displayed.
   + * - attributes: HTML attributes for the containing element.
   + *   The attributes.class element may contain one or more of the following
   + *   classes:
   + *   - node: The current template type (also known as a "theming hook").
   + *   - node--type-[type]: The current node type. For example, if the node is an
   + *     "Article" it would result in "node--type-article". Note that the machine
   + *     name will often be in a short form of the human readable label.
   + *   - node--view-mode-[view_mode]: The View Mode of the node; for example, a
   + *     teaser would result in: "node--view-mode-teaser", and
   + *     full: "node--view-mode-full".
   + *   The following are controlled through the node publishing options.
   + *   - node--promoted: Appears on nodes promoted to the front page.
   + *   - node--sticky: Appears on nodes ordered above other non-sticky nodes in
   + *     teaser listings.
   + *   - node--unpublished: Appears on unpublished nodes visible only to site
   + *     admins.
   + * - title_attributes: Same as attributes, except applied to the main title
   + *   tag that appears in the template.
   + * - content_attributes: Same as attributes, except applied to the main
   + *   content tag that appears in the template.
   + * - author_attributes: Same as attributes, except applied to the author of
   + *   the node tag that appears in the template.
   + * - title_prefix: Additional output populated by modules, intended to be
   + *   displayed in front of the main title tag that appears in the template.
   + * - title_suffix: Additional output populated by modules, intended to be
   + *   displayed after the main title tag that appears in the template.
   + * - view_mode: View mode; for example, "teaser" or "full".
   + * - teaser: Flag for the teaser state. Will be true if view_mode is 'teaser'.
   + * - page: Flag for the full page state. Will be true if view_mode is 'full'.
   + * - readmore: Flag for more state. Will be true if the teaser content of the
   + *   node cannot hold the main body content.
   + * - logged_in: Flag for authenticated user status. Will be true when the
   + *   current user is a logged-in member.
   + * - is_admin: Flag for admin user status. Will be true when the current user
   + *   is an administrator.
   + *
   + * @see template_preprocess_node()
   + *
   + * @todo Remove the id attribute (or make it a class), because if that gets
   + *   rendered twice on a page this is invalid CSS for example: two lists
   + *   in different view modes.
   + *
   + * @ingroup themeable
   + */
   +#}
   

   I think we don't need this entire comment block in a template that is used for testing purposes only.

9.2) Yup, missed that somehow

Also this should fix everything else.

This is a normal bug fix that is not disruptive and therefore permitted during beta. Committed bfdc741 and pushed to 8.0.x. Thanks!