Issue #2635238 by dsnopek, tim.plunkett: Contexts not mapped in time to use them in BlockInterface::access()

core/modules/block/src/BlockAccessControlHandler.php

@@ -127,7 +127,22 @@ class BlockAccessControlHandler extends EntityAccessControlHandler implements En
       }
       elseif ($this->resolveConditions($conditions, 'and') !== FALSE) {
         // Delegate to the plugin.
-        $access = $entity->getPlugin()->access($account, TRUE);
+        $block_plugin = $entity->getPlugin();
+        try {
+          if ($block_plugin instanceof ContextAwarePluginInterface) {
+            $contexts = $this->contextRepository->getRuntimeContexts(array_values($block_plugin->getContextMapping()));
+            $this->contextHandler->applyContextMapping($block_plugin, $contexts);
+          }
+          $access = $block_plugin->access($account, TRUE);
+        }
+        catch (ContextException $e) {
+          // Setting access to forbidden if any context is missing for the same
+          // reasons as with conditions (described in the comment above).
+          // @todo Avoid setting max-age 0 for some or all cases, for example by
+          //   treating available contexts without value differently in
+          //   https://www.drupal.org/node/2521956.
+          $access = AccessResult::forbidden()->setCacheMaxAge(0);
+        }
       }
       else {
         $access = AccessResult::forbidden();

core/modules/block/src/Tests/BlockUiTest.php

@@ -241,6 +241,7 @@ class BlockUiTest extends WebTestBase {
 
     $this->drupalGet('');
     $this->assertText('Test context-aware block');
+    $this->assertText('User context found.');
     $this->assertRaw($expected_text);
 
     // Test context mapping allows empty selection for optional contexts.
@@ -251,6 +252,7 @@ class BlockUiTest extends WebTestBase {
     $this->drupalPostForm(NULL, $edit, 'Save block');
     $this->drupalGet('');
     $this->assertText('No context mapping selected.');
+    $this->assertNoText('User context found.');
   }
 
   /**

core/modules/block/tests/modules/block_test/src/Plugin/Block/TestContextAwareBlock.php

@@ -8,6 +8,8 @@
 namespace Drupal\block_test\Plugin\Block;
 
 use Drupal\Core\Block\BlockBase;
+use Drupal\Core\Session\AccountInterface;
+use Drupal\user\UserInterface;
 
 /**
  * Provides a context-aware block.
@@ -35,4 +37,15 @@ class TestContextAwareBlock extends BlockBase {
     );
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  protected function blockAccess(AccountInterface $account) {
+    if ($this->getContextValue('user') instanceof UserInterface) {
+      drupal_set_message('User context found.');
+    }
+
+    return parent::blockAccess($account);
+  }
+
 }