Issue #2934354 by amateescu, Fabianx, alexpott: Expose cacheability metadata...

Issue #2934354 by amateescu, Fabianx, alexpott: Expose cacheability metadata in WorkspaceCacheContext

core/modules/workspace/src/WorkspaceCacheContext.php

@@ -47,7 +47,11 @@ public function getContext() {
    * {@inheritdoc}
    */
   public function getCacheableMetadata($type = NULL) {
-    return new CacheableMetadata();
+    // The active workspace will always be stored in the user's session.
+    $cacheability = new CacheableMetadata();
+    $cacheability->addCacheContexts(['session']);
+
+    return $cacheability;
   }
 
 }

core/modules/workspace/tests/src/Functional/WorkspaceSwitcherTest.php

@@ -3,6 +3,7 @@
 namespace Drupal\Tests\workspace\Functional;
 
 use Drupal\Tests\BrowserTestBase;
+use Drupal\Tests\system\Functional\Cache\AssertPageCacheContextsAndTagsTrait;
 
 /**
  * Tests workspace switching functionality.
@@ -11,6 +12,7 @@
  */
 class WorkspaceSwitcherTest extends BrowserTestBase {
 
+  use AssertPageCacheContextsAndTagsTrait;
   use WorkspaceTestUtilities;
 
   /**
@@ -52,6 +54,10 @@ public function testSwitchingWorkspaces() {
     $page = $this->getSession()->getPage();
     $page->findButton('Confirm')->click();
 
+    // Check that WorkspaceCacheContext provides the cache context used to
+    // support its functionality.
+    $this->assertCacheContext('session');
+
     $page->findLink($gravity->label());
   }
 
@@ -70,6 +76,10 @@ public function testQueryParameterNegotiator() {
     // The workspace switching via query parameter should persist.
     $this->drupalGet('<front>');
     $web_assert->elementContains('css', '.block-workspace-switcher', 'Stage');
+
+    // Check that WorkspaceCacheContext provides the cache context used to
+    // support its functionality.
+    $this->assertCacheContext('session');
   }
 
 }