.../Render/Placeholder/BigPipeStrategyTest.php     | 40 +++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/tests/src/Unit/Render/Placeholder/BigPipeStrategyTest.php b/tests/src/Unit/Render/Placeholder/BigPipeStrategyTest.php
index 65e7255..35babb8 100644
--- a/tests/src/Unit/Render/Placeholder/BigPipeStrategyTest.php
+++ b/tests/src/Unit/Render/Placeholder/BigPipeStrategyTest.php
@@ -42,9 +42,15 @@ class BigPipeStrategyTest extends UnitTestCase {
 
     $big_pipe_strategy = new BigPipeStrategy($session_configuration->reveal(), $request_stack->reveal());
     $processed_placeholders = $big_pipe_strategy->processPlaceholders($placeholders);
-    $this->assertSame($expected_big_pipe_placeholders, $processed_placeholders);
+
     if ($request_has_session) {
       $this->assertSameSize($placeholders, $processed_placeholders, 'BigPipe is able to deliver all placeholders.');
+      foreach (array_keys($placeholders) as $placeholder) {
+        $this->assertSame($expected_big_pipe_placeholders[$placeholder], $processed_placeholders[$placeholder], "Verifying how BigPipeStrategy handles the placeholder '$placeholder'");
+      }
+    }
+    else {
+      $this->assertSame(0, count($processed_placeholders));
     }
   }
 
@@ -142,6 +148,36 @@ class BigPipeStrategyTest extends UnitTestCase {
       ],
     ];
 
+    // Edge case: non-#lazy_builder placeholder.
+    $placeholders['<time>CURRENT TIME</time>'] = [
+      '#pre_render' => ['current_time'],
+    ];
+    $current_time_big_pipe_placeholder = [
+      '#markup' => '<div data-big-pipe-placeholder-id="timecurrent-timetime"></div>',
+      '#cache' => $cacheability_depends_on_session_and_nojs_cookie,
+      '#attached' => [
+        'library' => ['big_pipe/big_pipe'],
+        'drupalSettings' => [
+          'bigPipePlaceholderIds' => [
+            'timecurrent-timetime' => TRUE,
+          ],
+        ],
+        'big_pipe_placeholders' => [
+          'timecurrent-timetime' => $placeholders['<time>CURRENT TIME</time>'],
+        ],
+      ],
+    ];
+    $current_time_big_pipe_nojs_placeholder = [
+      '#markup' => '<div data-bigpipe-nojs-placeholder-id="timecurrent-timetime"></div>',
+      '#cache' => $cacheability_depends_on_session_and_nojs_cookie,
+      '#attached' => [
+        'big_pipe_nojs_placeholders' => [
+          '<div data-big-pipe-nojs-placeholder-id="timecurrent-timetime"></div>' => $placeholders['<time>CURRENT TIME</time>'],
+        ],
+      ],
+    ];
+
+
     return [
       'no session, no-JS cookie absent' => [$placeholders, FALSE, FALSE, []],
       'no session, no-JS cookie present' => [$placeholders, FALSE, TRUE, []],
@@ -150,12 +186,14 @@ class BigPipeStrategyTest extends UnitTestCase {
         'form_action_cc611e1d' => $form_action_big_pipe_nojs_placeholder,
         '22dcc695f4a22e809a62d8eb7addd6fccecfbf31' => $csrf_token_big_pipe_nojs_placeholder,
         '<hello' => $hello_big_pipe_nojs_placeholder,
+        '<time>CURRENT TIME</time>' => $current_time_big_pipe_placeholder,
       ]],
       'session, no-JS cookie present: no-JS BigPipe placeholder used for HTML placeholders' => [$placeholders, TRUE, TRUE, [
         $messages_placeholder_markup => $messages_big_pipe_nojs_placeholder,
         'form_action_cc611e1d' => $form_action_big_pipe_nojs_placeholder,
         '22dcc695f4a22e809a62d8eb7addd6fccecfbf31' => $csrf_token_big_pipe_nojs_placeholder,
         '<hello' => $hello_big_pipe_nojs_placeholder,
+        '<time>CURRENT TIME</time>' => $current_time_big_pipe_nojs_placeholder,
       ]],
     ];
   }