core/modules/big_pipe/src/Tests/BigPipeTest.php       | 19 +++++++++++--------
 .../tests/src/Functional/BigPipeSessionlessTest.php   |  2 +-
 2 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/core/modules/big_pipe/src/Tests/BigPipeTest.php b/core/modules/big_pipe/src/Tests/BigPipeTest.php
index 4a73614..58ea5d4 100644
--- a/core/modules/big_pipe/src/Tests/BigPipeTest.php
+++ b/core/modules/big_pipe/src/Tests/BigPipeTest.php
@@ -6,7 +6,6 @@
 use Drupal\big_pipe\Render\BigPipe;
 use Drupal\Component\Serialization\Json;
 use Drupal\Component\Utility\Html;
-use Drupal\Core\Cache\Cache;
 use Drupal\Core\Logger\RfcLogLevel;
 use Drupal\Core\Url;
 use Drupal\simpletest\WebTestBase;
@@ -161,6 +160,7 @@ public function testBigPipe() {
     $this->assertBigPipeResponseHeadersPresent();
     $this->assertNoCacheTag('cache_tag_set_in_lazy_builder');
 
+    $this->setCsrfTokenSeedInTestEnvironment();
     $cases = $this->getTestCases();
     $this->assertBigPipeNoJsPlaceholders([
       $cases['edge_case__invalid_html']->bigPipeNoJsPlaceholder     => $cases['edge_case__invalid_html']->embeddedHtmlResponse,
@@ -240,6 +240,7 @@ public function testBigPipeNoJs() {
     $this->assertBigPipeResponseHeadersPresent();
     $this->assertNoCacheTag('cache_tag_set_in_lazy_builder');
 
+    $this->setCsrfTokenSeedInTestEnvironment();
     $cases = $this->getTestCases();
     $this->assertBigPipeNoJsPlaceholders([
       $cases['edge_case__invalid_html']->bigPipeNoJsPlaceholder           => $cases['edge_case__invalid_html']->embeddedHtmlResponse,
@@ -405,16 +406,18 @@ protected function assertBigPipePlaceholders(array $expected_big_pipe_placeholde
   }
 
   /**
+   * Ensures CSRF tokens can be generated for the current user's session.
+   */
+  protected function setCsrfTokenSeedInTestEnvironment() {
+    $session_data = $this->container->get('session_handler.write_safe')->read($this->cookies[$this->getSessionName()]['value']);
+    $csrf_token_seed = unserialize(explode('_sf2_meta|', $session_data)[1])['s'];
+    $this->container->get('session_manager.metadata_bag')->setCsrfTokenSeed($csrf_token_seed);
+  }
+
+  /**
    * @return \Drupal\big_pipe\Tests\BigPipePlaceholderTestCase[]
    */
   protected function getTestCases($has_session = TRUE) {
-    if ($has_session) {
-      // Ensure we can generate CSRF tokens for the current user's session.
-      $session_data = $this->container->get('session_handler.write_safe')->read($this->cookies[$this->getSessionName()]['value']);
-      $csrf_token_seed = unserialize(explode('_sf2_meta|', $session_data)[1])['s'];
-      $this->container->get('session_manager.metadata_bag')->setCsrfTokenSeed($csrf_token_seed);
-    }
-
     return BigPipePlaceholderTestCases::cases($this->container, $this->rootUser);
   }
 
diff --git a/modules/big_pipe_sessionless/tests/src/Functional/BigPipeSessionlessTest.php b/modules/big_pipe_sessionless/tests/src/Functional/BigPipeSessionlessTest.php
index c926b5f..6e66de0 100644
--- a/modules/big_pipe_sessionless/tests/src/Functional/BigPipeSessionlessTest.php
+++ b/modules/big_pipe_sessionless/tests/src/Functional/BigPipeSessionlessTest.php
@@ -71,7 +71,7 @@ public function testBigPipeNoSession() {
       $this->assertRaw('<a href="' . base_path() . 'big_pipe_test" data-drupal-link-system-path="big_pipe_test" class="is-active">This should be marked active</a>');
       $this->assertRaw('<a href="' . base_path() . '" data-drupal-link-system-path="&lt;front&gt;">This should be marked inactive</a>');
 
-      $cases = $this->getTestCases(FALSE);
+      $cases = $this->getTestCases();
       $this->assertBigPipeNoJsPlaceholders([
         $cases['edge_case__invalid_html']->bigPipeNoJsPlaceholder => $cases['edge_case__invalid_html']->embeddedHtmlResponse,
         $cases['html_attribute_value']->bigPipeNoJsPlaceholder => $cases['html_attribute_value']->embeddedHtmlResponse,