Issue #2873732 by vijaycs85, GaëlG: Array to string conversion in...

Issue #2873732 by vijaycs85, GaëlG: Array to string conversion in CacheContextsManager::convertTokensToKeys() because of the 'cookies' cache context

core/lib/Drupal/Core/Cache/Context/CookiesCacheContext.php

@@ -25,7 +25,12 @@ public static function getLabel() {
    */
   public function getContext($cookie = NULL) {
     if ($cookie === NULL) {
-      return $this->requestStack->getCurrentRequest()->cookies->all();
+      $cookies = $this->requestStack->getCurrentRequest()->cookies->all();
+      // Sort the cookies by names, to always set the same context if the cookies
+      // are the same but in a different order.
+      ksort($cookies);
+      // Use http_build_query() to get a short string from the cookies array.
+      return http_build_query($cookies);
     }
     else {
       return $this->requestStack->getCurrentRequest()->cookies->get($cookie);

core/tests/Drupal/Tests/Core/Cache/Context/CookieCacheContextTest.php

+<?php
+
+namespace Drupal\Tests\Core\Cache\Context;
+
+use Drupal\Core\Cache\Context\CookiesCacheContext;
+use Drupal\Tests\UnitTestCase;
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\RequestStack;
+
+/**
+ * @coversDefaultClass \Drupal\Core\Cache\Context\CookiesCacheContext
+ * @group Cache
+ */
+class CookieCacheContextTest extends UnitTestCase {
+
+  /**
+   * @covers ::getContext
+   *
+   * @dataProvider providerTestGetContext
+   */
+  public function testGetContext($cookies, $cookie_name, $context) {
+    $request_stack = new RequestStack();
+    $request = Request::create('/', 'GET');
+    foreach ($cookies as $cookie => $value) {
+      $request->cookies->set($cookie, $value);
+    }
+    $request_stack->push($request);
+    $cache_context = new CookiesCacheContext($request_stack);
+    $this->assertSame($cache_context->getContext($cookie_name), $context);
+  }
+
+  /**
+   * Provides a list of cookies and expected cache contexts.
+   */
+  public function providerTestGetContext() {
+    return [
+      [['foo' => 1, 'bar' => 2, 'baz' => 3], 'foo', 1],
+      // Context is ordered by cookie name.
+      [['foo' => 1, 'bar' => 2, 'baz' => 3], NULL, 'bar=2&baz=3&foo=1'],
+    ];
+  }
+
+}