Move all files to 2017/

2017/web/core/modules/layout_discovery/layout_discovery.info.yml

@@ -0,0 +1,6 @@
+name: 'Layout Discovery'
+type: module
+description: 'Provides a way for modules or themes to register layouts.'
+package: Core
+version: VERSION
+core: 8.x

2017/web/core/modules/layout_discovery/layout_discovery.install

@@ -0,0 +1,22 @@
+<?php
+
+/**
+ * @file
+ * Install, update, and uninstall functions for the Layout Discovery module.
+ */
+
+/**
+ * Implements hook_requirements().
+ */
+function layout_discovery_requirements($phase) {
+  $requirements = [];
+  if ($phase === 'install') {
+    if (\Drupal::moduleHandler()->moduleExists('layout_plugin')) {
+      $requirements['layout_discovery'] = [
+        'description' => t('Layout Discovery cannot be installed because the Layout Plugin module is installed and incompatible.'),
+        'severity' => REQUIREMENT_ERROR,
+      ];
+    }
+  }
+  return $requirements;
+}

2017/web/core/modules/layout_discovery/layout_discovery.layouts.yml

@@ -0,0 +1,108 @@
+layout_onecol:
+  label: 'One column'
+  path: layouts/onecol
+  template: layout--onecol
+  library: layout_discovery/onecol
+  category: 'Columns: 1'
+  default_region: content
+  icon_map:
+    - [content]
+  regions:
+    content:
+      label: Content
+
+layout_twocol:
+  label: 'Two column'
+  path: layouts/twocol
+  template: layout--twocol
+  library: layout_discovery/twocol
+  category: 'Columns: 2'
+  default_region: first
+  icon_map:
+    - [top]
+    - [first, second]
+    - [bottom]
+  regions:
+    top:
+      label: Top
+    first:
+      label: First
+    second:
+      label: Second
+    bottom:
+      label: Bottom
+
+layout_twocol_bricks:
+  label: 'Two column bricks'
+  path: layouts/twocol_bricks
+  template: layout--twocol-bricks
+  library: layout_discovery/twocol_bricks
+  category: 'Columns: 2'
+  default_region: middle
+  icon_map:
+    - [top]
+    - [first_above, second_above]
+    - [middle]
+    - [first_below, second_below]
+    - [bottom]
+  regions:
+    top:
+      label: Top
+    first_above:
+      label: 'First above'
+    second_above:
+      label: 'Second above'
+    middle:
+      label: Middle
+    first_below:
+      label: 'First below'
+    second_below:
+      label: 'Second below'
+    bottom:
+      label: Bottom
+
+layout_threecol_25_50_25:
+  label: 'Three column 25/50/25'
+  path: layouts/threecol_25_50_25
+  template: layout--threecol-25-50-25
+  library: layout_discovery/threecol_25_50_25
+  category: 'Columns: 3'
+  default_region: second
+  icon_map:
+    - [top]
+    - [first, second, second, third]
+    - [bottom]
+  regions:
+    top:
+      label: Top
+    first:
+      label: First
+    second:
+      label: Second
+    third:
+      label: Third
+    bottom:
+      label: Bottom
+
+layout_threecol_33_34_33:
+  label: 'Three column 33/34/33'
+  path: layouts/threecol_33_34_33
+  template: layout--threecol-33-34-33
+  library: layout_discovery/threecol_33_34_33
+  category: 'Columns: 3'
+  default_region: first
+  icon_map:
+    - [top]
+    - [first, second, third]
+    - [bottom]
+  regions:
+    top:
+      label: Top
+    first:
+      label: First
+    second:
+      label: Second
+    third:
+      label: Third
+    bottom:
+      label: Bottom

2017/web/core/modules/layout_discovery/layout_discovery.libraries.yml

@@ -0,0 +1,25 @@
+onecol:
+  version: VERSION
+  css:
+    theme:
+      layouts/onecol/onecol.css: {}
+twocol_bricks:
+  version: VERSION
+  css:
+    theme:
+      layouts/twocol_bricks/twocol_bricks.css: {}
+twocol:
+  version: VERSION
+  css:
+    theme:
+      layouts/twocol/twocol.css: {}
+threecol_25_50_25:
+  version: VERSION
+  css:
+    theme:
+      layouts/threecol_25_50_25/threecol_25_50_25.css: {}
+threecol_33_34_33:
+  version: VERSION
+  css:
+    theme:
+      layouts/threecol_33_34_33/threecol_33_34_33.css: {}

2017/web/core/modules/layout_discovery/layout_discovery.module

@@ -0,0 +1,50 @@
+<?php
+
+/**
+ * @file
+ * Provides hook implementations for Layout Discovery.
+ */
+
+use Drupal\Core\Render\Element;
+use Drupal\Core\Template\Attribute;
+
+/**
+ * Implements hook_help().
+ */
+function layout_discovery_help($route_name) {
+  switch ($route_name) {
+    case 'help.page.layout_discovery':
+      $output = '<h3>' . t('About') . '</h3>';
+      $output .= '<p>' . t('Layout Discovery allows modules or themes to register layouts, and for other modules to list the available layouts and render them.') . '</p>';
+      $output .= '<p>' . t('For more information, see the <a href=":layout-discovery-documentation">online documentation for the Layout Discovery module</a>.', [':layout-discovery-documentation' => 'https://www.drupal.org/docs/8/api/layout-api']) . '</p>';
+      return $output;
+  }
+}
+
+/**
+ * Implements hook_theme().
+ */
+function layout_discovery_theme() {
+  return \Drupal::service('plugin.manager.core.layout')->getThemeImplementations();
+}
+
+/**
+ * Prepares variables for layout templates.
+ *
+ * @param array &$variables
+ *   An associative array containing:
+ *   - content: An associative array containing the properties of the element.
+ *     Properties used: #settings, #layout.
+ */
+function template_preprocess_layout(&$variables) {
+  $variables['settings'] = isset($variables['content']['#settings']) ? $variables['content']['#settings'] : [];
+  $variables['layout'] = isset($variables['content']['#layout']) ? $variables['content']['#layout'] : [];
+
+  // Create an attributes variable for each region.
+  foreach (Element::children($variables['content']) as $name) {
+    if (!isset($variables['content'][$name]['#attributes'])) {
+      $variables['content'][$name]['#attributes'] = [];
+    }
+    $variables['region_attributes'][$name] = new Attribute($variables['content'][$name]['#attributes']);
+  }
+}

2017/web/core/modules/layout_discovery/layout_discovery.services.yml

@@ -0,0 +1,7 @@
+services:
+  plugin.manager.core.layout:
+    class: Drupal\Core\Layout\LayoutPluginManager
+    arguments: ['@container.namespaces', '@cache.discovery', '@module_handler', '@theme_handler']
+  layout.icon_builder:
+    class: Drupal\Core\Layout\Icon\SvgIconBuilder
+    shared: false

2017/web/core/modules/layout_discovery/layouts/onecol/layout--onecol.html.twig

@@ -0,0 +1,25 @@
+{#
+/**
+ * @file
+ * Default theme implementation to display a one-column layout.
+ *
+ * Available variables:
+ * - content: The content for this layout.
+ * - attributes: HTML attributes for the layout <div>.
+ *
+ * @ingroup themeable
+ */
+#}
+{%
+  set classes = [
+    'layout',
+    'layout--onecol',
+  ]
+%}
+{% if content %}
+  <div{{ attributes.addClass(classes) }}>
+    <div {{ region_attributes.content.addClass('layout__region', 'layout__region--content') }}>
+      {{ content.content }}
+    </div>
+  </div>
+{% endif %}

2017/web/core/modules/layout_discovery/layouts/onecol/onecol.css

@@ -0,0 +1,7 @@
+/*
+ * @file
+ * Provides the layout styles for layout_onecol.
+ */
+.layout--onecol .layout__region {
+  width: 100%;
+}

2017/web/core/modules/layout_discovery/layouts/threecol_25_50_25/layout--threecol-25-50-25.html.twig

@@ -0,0 +1,54 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a three column layout.
+ *
+ * This template provides a three column 25%-50%-25% display layout, with
+ * additional areas for the top and the bottom.
+ *
+ * Available variables:
+ * - content: The content for this layout.
+ * - attributes: HTML attributes for the layout <div>.
+ *
+ * @ingroup themeable
+ */
+#}
+{%
+  set classes = [
+    'layout',
+    'layout--threecol-25-50-25',
+  ]
+%}
+{% if content %}
+  <div{{ attributes.addClass(classes) }}>
+    {% if content.top %}
+      <div {{ region_attributes.top.addClass('layout__region', 'layout__region--top') }}>
+        {{ content.top }}
+      </div>
+    {% endif %}
+
+    {% if content.first %}
+      <div {{ region_attributes.first.addClass('layout__region', 'layout__region--first') }}>
+        {{ content.first }}
+      </div>
+    {% endif %}
+
+    {% if content.second %}
+      <div {{ region_attributes.second.addClass('layout__region', 'layout__region--second') }}>
+        {{ content.second }}
+      </div>
+    {% endif %}
+
+    {% if content.third %}
+      <div {{ region_attributes.third.addClass('layout__region', 'layout__region--third') }}>
+        {{ content.third }}
+      </div>
+    {% endif %}
+
+    {% if content.bottom %}
+      <div {{ region_attributes.bottom.addClass('layout__region', 'layout__region--bottom') }}>
+        {{ content.bottom }}
+      </div>
+    {% endif %}
+  </div>
+{% endif %}

2017/web/core/modules/layout_discovery/layouts/threecol_25_50_25/threecol_25_50_25.css

@@ -0,0 +1,26 @@
+/*
+ * @file
+ * Provides the layout styles for layout_threecol_25_50_25.
+ *
+ * @todo Using display: flex requires https://www.drupal.org/node/2842298 to be
+ * in before this can be marked as stable.
+ */
+.layout--threecol-25-50-25 {
+  display: flex;
+  flex-wrap: wrap;
+}
+
+.layout--threecol-25-50-25 > .layout__region,
+.layout--threecol-25-50-25 > .layout__region--second {
+  flex: 0 1 100%;
+}
+
+@media screen and (min-width: 40em) {
+  .layout--threecol-25-50-25 > .layout__region--first,
+  .layout--threecol-25-50-25 > .layout__region--third {
+    flex: 0 1 25%;
+  }
+  .layout--threecol-25-50-25 > .layout__region--second {
+    flex: 0 1 50%;
+  }
+}

2017/web/core/modules/layout_discovery/layouts/threecol_33_34_33/layout--threecol-33-34-33.html.twig

@@ -0,0 +1,54 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a three column layout.
+ *
+ * This template provides a three column 33%-34%-33% display layout, with
+ * additional areas for the top and the bottom.
+ *
+ * Available variables:
+ * - content: The content for this layout.
+ * - attributes: HTML attributes for the layout <div>.
+ *
+ * @ingroup themeable
+ */
+#}
+{%
+  set classes = [
+    'layout',
+    'layout--threecol-33-34-33',
+  ]
+%}
+{% if content %}
+  <div{{ attributes.addClass(classes) }}>
+    {% if content.top %}
+      <div {{ region_attributes.top.addClass('layout__region', 'layout__region--top') }}>
+        {{ content.top }}
+      </div>
+    {% endif %}
+
+    {% if content.first %}
+      <div {{ region_attributes.first.addClass('layout__region', 'layout__region--first') }}>
+        {{ content.first }}
+      </div>
+    {% endif %}
+
+    {% if content.second %}
+      <div {{ region_attributes.second.addClass('layout__region', 'layout__region--second') }}>
+        {{ content.second }}
+      </div>
+    {% endif %}
+
+    {% if content.third %}
+      <div {{ region_attributes.third.addClass('layout__region', 'layout__region--third') }}>
+        {{ content.third }}
+      </div>
+    {% endif %}
+
+    {% if content.bottom %}
+      <div {{ region_attributes.bottom.addClass('layout__region', 'layout__region--bottom') }}>
+        {{ content.bottom }}
+      </div>
+    {% endif %}
+  </div>
+{% endif %}

2017/web/core/modules/layout_discovery/layouts/threecol_33_34_33/threecol_33_34_33.css

@@ -0,0 +1,26 @@
+/*
+ * @file
+ * Provides the layout styles for layout_threecol_33_34_33.
+ *
+ * @todo Using display: flex requires https://www.drupal.org/node/2842298 to be
+ * in before this can be marked as stable.
+ */
+
+.layout--threecol-33-34-33 {
+  display: flex;
+  flex-wrap: wrap;
+}
+
+.layout--threecol-33-34-33 > .layout__region {
+  flex: 0 1 100%;
+}
+
+@media screen and (min-width: 40em) {
+  .layout--threecol-33-34-33 > .layout__region--first,
+  .layout--threecol-33-34-33 > .layout__region--third {
+    flex: 0 1 33%;
+  }
+  .layout--threecol-33-34-33 > .layout__region--second {
+    flex: 0 1 34%;
+  }
+}

2017/web/core/modules/layout_discovery/layouts/twocol/layout--twocol.html.twig

@@ -0,0 +1,45 @@
+{#
+/**
+ * @file
+ * Default theme implementation to display a two-column layout.
+ *
+ * Available variables:
+ * - content: The content for this layout.
+ * - attributes: HTML attributes for the layout <div>.
+ *
+ * @ingroup themeable
+ */
+#}
+{%
+  set classes = [
+    'layout',
+    'layout--twocol',
+  ]
+%}
+{% if content %}
+  <div{{ attributes.addClass(classes) }}>
+    {% if content.top %}
+      <div {{ region_attributes.top.addClass('layout__region', 'layout__region--top') }}>
+        {{ content.top }}
+      </div>
+    {% endif %}
+
+    {% if content.first %}
+      <div {{ region_attributes.first.addClass('layout__region', 'layout__region--first') }}>
+        {{ content.first }}
+      </div>
+    {% endif %}
+
+    {% if content.second %}
+      <div {{ region_attributes.second.addClass('layout__region', 'layout__region--second') }}>
+        {{ content.second }}
+      </div>
+    {% endif %}
+
+    {% if content.bottom %}
+      <div {{ region_attributes.bottom.addClass('layout__region', 'layout__region--bottom') }}>
+        {{ content.bottom }}
+      </div>
+    {% endif %}
+  </div>
+{% endif %}

2017/web/core/modules/layout_discovery/layouts/twocol/twocol.css

@@ -0,0 +1,23 @@
+/*
+ * @file
+ * Provides the layout styles for layout_twocol.
+ *
+ * @todo Using display: flex requires https://www.drupal.org/node/2842298 to be
+ * in before this can be marked as stable.
+ */
+
+.layout--twocol {
+  display: flex;
+  flex-wrap: wrap;
+}
+
+.layout--twocol > .layout__region {
+  flex: 0 1 100%;
+}
+
+@media screen and (min-width: 40em) {
+  .layout--twocol > .layout__region--first,
+  .layout--twocol > .layout__region--second {
+    flex: 0 1 50%;
+  }
+}

2017/web/core/modules/layout_discovery/layouts/twocol_bricks/layout--twocol-bricks.html.twig

@@ -0,0 +1,66 @@
+{#
+/**
+ * @file
+ * Default theme implementation for a two column layout.
+ *
+ * This template provides a two column display layout with full width areas at
+ * the top, bottom and in the middle.
+ *
+ * Available variables:
+ * - content: The content for this layout.
+ * - attributes: HTML attributes for the layout <div>.
+ *
+ * @ingroup themeable
+ */
+#}
+{%
+  set classes = [
+    'layout',
+    'layout--twocol-bricks',
+  ]
+%}
+{% if content %}
+  <div{{ attributes.addClass(classes) }}>
+    {% if content.top %}
+      <div {{ region_attributes.top.addClass('layout__region', 'layout__region--top') }}>
+        {{ content.top }}
+      </div>
+    {% endif %}
+
+    {% if content.first_above %}
+      <div {{ region_attributes.first_above.addClass('layout__region', 'layout__region--first-above') }}>
+        {{ content.first_above }}
+      </div>
+    {% endif %}
+
+    {% if content.second_above %}
+      <div {{ region_attributes.second_above.addClass('layout__region', 'layout__region--second-above') }}>
+        {{ content.second_above }}
+      </div>
+    {% endif %}
+
+    {% if content.middle %}
+      <div {{ region_attributes.middle.addClass('layout__region', 'layout__region--middle') }}>
+        {{ content.middle }}
+      </div>
+    {% endif %}
+
+    {% if content.first_below %}
+      <div {{ region_attributes.first_below.addClass('layout__region', 'layout__region--first-below') }}>
+        {{ content.first_below }}
+      </div>
+    {% endif %}
+
+    {% if content.second_below %}
+      <div {{ region_attributes.second_below.addClass('layout__region', 'layout__region--second-below') }}>
+        {{ content.second_below }}
+      </div>
+    {% endif %}
+
+    {% if content.bottom %}
+      <div {{ region_attributes.bottom.addClass('layout__region', 'layout__region--bottom') }}>
+        {{ content.bottom }}
+      </div>
+    {% endif %}
+  </div>
+{% endif %}

2017/web/core/modules/layout_discovery/layouts/twocol_bricks/twocol_bricks.css

@@ -0,0 +1,25 @@
+/*
+ * @file
+ * Provides the layout styles for layout_twocol_bricks.
+ *
+ * @todo Using display: flex requires https://www.drupal.org/node/2842298 to be
+ * in before this can be marked as stable.
+ */
+
+.layout--twocol-bricks {
+  display: flex;
+  flex-wrap: wrap;
+}
+
+.layout--twocol-bricks > .layout__region {
+  flex: 0 1 100%;
+}
+
+@media screen and (min-width: 40em) {
+  .layout--twocol-bricks > .layout__region--first-above,
+  .layout--twocol-bricks > .layout__region--second-above,
+  .layout--twocol-bricks > .layout__region--first-below,
+  .layout--twocol-bricks > .layout__region--second-below {
+    flex: 0 1 50%;
+  }
+}

2017/web/core/modules/layout_discovery/templates/layout.html.twig

@@ -0,0 +1,23 @@
+{#
+/**
+ * @file
+ * Template for a generic layout.
+ */
+#}
+{%
+  set classes = [
+    'layout',
+    'layout--' ~ layout.id|clean_class,
+  ]
+%}
+{% if content %}
+  <div{{ attributes.addClass(classes) }}>
+    {% for region in layout.getRegionNames %}
+      {% if content[region] %}
+        <div {{ region_attributes[region].addClass('layout__region', 'layout__region--' ~ region|clean_class) }}>
+          {{ content[region] }}
+        </div>
+      {% endif %}
+    {% endfor %}
+  </div>
+{% endif %}

2017/web/core/modules/layout_discovery/tests/src/Kernel/LayoutTest.php

@@ -0,0 +1,237 @@
+<?php
+
+namespace Drupal\Tests\layout_discovery\Kernel;
+
+use Drupal\Core\Form\FormState;
+use Drupal\KernelTests\KernelTestBase;
+
+/**
+ * Tests Layout functionality.
+ *
+ * @group Layout
+ */
+class LayoutTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['system', 'layout_discovery', 'layout_test'];
+
+  /**
+   * The layout plugin manager.
+   *
+   * @var \Drupal\Core\Layout\LayoutPluginManagerInterface
+   */
+  protected $layoutPluginManager;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    $this->layoutPluginManager = $this->container->get('plugin.manager.core.layout');
+  }
+
+  /**
+   * Tests that a layout provided by a theme has the preprocess function set.
+   */
+  public function testThemeProvidedLayout() {
+    $this->container->get('theme_installer')->install(['test_layout_theme']);
+    $this->config('system.theme')->set('default', 'test_layout_theme')->save();
+
+    $theme_definitions = $this->container->get('theme.registry')->get();
+    $this->assertTrue(in_array('template_preprocess_layout', $theme_definitions['test_layout_theme']['preprocess functions']));
+  }
+
+  /**
+   * Test rendering a layout.
+   *
+   * @dataProvider renderLayoutData
+   */
+  public function testRenderLayout($layout_id, $config, $regions, array $html) {
+    $layout = $this->layoutPluginManager->createInstance($layout_id, $config);
+    $built['layout'] = $layout->build($regions);
+    $built['layout']['#prefix'] = 'Test prefix' . "\n";
+    $built['layout']['#suffix'] = 'Test suffix' . "\n";
+
+    // Assume each layout is contained by a form, in order to ensure the
+    // building of the layout does not interfere with form processing.
+    $form_state = new FormState();
+    $form_builder = $this->container->get('form_builder');
+    $form_builder->prepareForm('the_form_id', $built, $form_state);
+    $form_builder->processForm('the_form_id', $built, $form_state);
+
+    $this->render($built);
+
+    // Add in the wrapping form elements and prefix/suffix.
+    array_unshift($html, 'Test prefix');
+    array_unshift($html, '<form data-drupal-selector="the-form-id" action="/" method="post" id="the-form-id" accept-charset="UTF-8">');
+    // Retrieve the build ID from the rendered HTML since the string is random.
+    $build_id_input = $this->cssSelect('input[name="form_build_id"]')[0]->asXML();
+    $form_id_input = '<input data-drupal-selector="edit-the-form-id" type="hidden" name="form_id" value="the_form_id"/>';
+    $html[] = 'Test suffix';
+    $html[] = $build_id_input . $form_id_input . '</form>';
+
+    // Match the HTML to the full form element.
+    $this->assertSame(implode("\n", $html), $this->cssSelect('#the-form-id')[0]->asXML());
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function render(array &$elements) {
+    $content = parent::render($elements);
+    // Strip leading whitespace from every line.
+    $this->content = preg_replace('/^\s+/m', '', $content);
+    return $this->content;
+  }
+
+  /**
+   * Data provider for testRenderLayout().
+   */
+  public function renderLayoutData() {
+    $html = [];
+    $html[] = '<div data-drupal-selector="edit-layout" class="layout layout--onecol">';
+    $html[] = '<div data-drupal-selector="edit-content" class="layout__region layout__region--content">';
+    $html[] = 'This is the content';
+    $html[] = '</div>';
+    $html[] = '</div>';
+    $data['layout_onecol'] = [
+      'layout_onecol',
+      [],
+      [
+        'content' => [
+          '#markup' => 'This is the content',
+        ],
+      ],
+      $html,
+    ];
+
+    $html = [];
+    $html[] = '<div data-drupal-selector="edit-layout" class="layout-example-1col clearfix">';
+    $html[] = '<div data-drupal-selector="edit-top" class="region-top">';
+    $html[] = 'This string added by #process.';
+    $html[] = '</div>';
+    $html[] = '<div data-drupal-selector="edit-bottom" class="region-bottom">';
+    $html[] = 'This is the bottom';
+    $html[] = '</div>';
+    $html[] = '</div>';
+    $data['layout_test_1col_with_form'] = [
+      'layout_test_1col',
+      [],
+      [
+        'top' => [
+          '#process' => [[static::class, 'processCallback']],
+        ],
+        'bottom' => [
+          '#markup' => 'This is the bottom',
+        ],
+      ],
+      $html,
+    ];
+
+    $html = [];
+    $html[] = '<div data-drupal-selector="edit-layout" class="layout-example-1col clearfix">';
+    $html[] = '<div data-drupal-selector="edit-top" class="region-top">';
+    $html[] = 'This is the top';
+    $html[] = '</div>';
+    $html[] = '<div data-drupal-selector="edit-bottom" class="region-bottom">';
+    $html[] = 'This is the bottom';
+    $html[] = '</div>';
+    $html[] = '</div>';
+    $data['layout_test_1col'] = [
+      'layout_test_1col',
+      [],
+      [
+        'top' => [
+          '#markup' => 'This is the top',
+        ],
+        'bottom' => [
+          '#markup' => 'This is the bottom',
+        ],
+      ],
+      $html,
+    ];
+
+    $html = [];
+    $html[] = '<div data-drupal-selector="edit-layout" class="layout layout--layout-test-1col-no-template">';
+    $html[] = '<div data-drupal-selector="edit-top" class="layout__region layout__region--top">';
+    $html[] = 'This is the top';
+    $html[] = '</div>';
+    $html[] = '<div data-drupal-selector="edit-bottom" class="layout__region layout__region--bottom">';
+    $html[] = 'This is the bottom';
+    $html[] = '</div>';
+    $html[] = '</div>';
+    $data['layout_test_1col_no_template'] = [
+      'layout_test_1col_no_template',
+      [],
+      [
+        'top' => [
+          '#markup' => 'This is the top',
+        ],
+        'bottom' => [
+          '#markup' => 'This is the bottom',
+        ],
+      ],
+      $html,
+    ];
+
+    $html = [];
+    $html[] = '<div data-drupal-selector="edit-layout" class="layout-example-2col clearfix">';
+    $html[] = '<div data-drupal-selector="edit-left" class="class-added-by-preprocess region-left">';
+    $html[] = 'This is the left';
+    $html[] = '</div>';
+    $html[] = '<div data-drupal-selector="edit-right" class="region-right">';
+    $html[] = 'This is the right';
+    $html[] = '</div>';
+    $html[] = '</div>';
+    $data['layout_test_2col'] = [
+      'layout_test_2col',
+      [],
+      [
+        'left' => [
+          '#markup' => 'This is the left',
+        ],
+        'right' => [
+          '#markup' => 'This is the right',
+        ],
+      ],
+      $html,
+    ];
+
+    $html = [];
+    $html[] = '<div data-drupal-selector="edit-layout" class="layout-test-plugin clearfix">';
+    $html[] = '<div>';
+    $html[] = '<span class="setting-1-label">Blah: </span>';
+    $html[] = 'Config value';
+    $html[] = '</div>';
+    $html[] = '<div data-drupal-selector="edit-main" class="region-main">';
+    $html[] = 'Main region';
+    $html[] = '</div>';
+    $html[] = '</div>';
+    $data['layout_test_plugin'] = [
+      'layout_test_plugin',
+      [
+        'setting_1' => 'Config value',
+      ],
+      [
+        'main' => [
+          '#markup' => 'Main region',
+        ],
+      ],
+      $html,
+    ];
+
+    return $data;
+  }
+
+  /**
+   * Provides a test #process callback.
+   */
+  public static function processCallback($element) {
+    $element['#markup'] = 'This string added by #process.';
+    return $element;
+  }
+
+}

2017/web/core/modules/layout_discovery/tests/themes/test_layout_theme/templates/test-layout-theme.html.twig

@@ -0,0 +1 @@
+{{ content.content }}

2017/web/core/modules/layout_discovery/tests/themes/test_layout_theme/test_layout_theme.info.yml

@@ -0,0 +1,6 @@
+name: 'Test layout theme'
+type: theme
+description: 'Theme for testing a theme-provided layout'
+version: VERSION
+base theme: classy
+core: 8.x

2017/web/core/modules/layout_discovery/tests/themes/test_layout_theme/test_layout_theme.layouts.yml

@@ -0,0 +1,7 @@
+test_layout_theme:
+  label: 'Test Layout - Theme'
+  category: 'Test Layout Theme'
+  template: templates/test-layout-theme
+  regions:
+    content:
+      label: Content