From 0b2aabe3f371bef71e1569f82d1bbf891cb01bc4 Mon Sep 17 00:00:00 2001
From: JPeer264 <jan.peer@sentry.io>
Date: Mon, 12 Oct 2026 13:34:02 +0200
Subject: [PATCH] test(browser): Keep whitespace text out of the handlers-lcp
 page
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The space between the inline <img> and <button> was painted as a text
run in <body> (68px²). When it painted in the same frame as the image,
Chromium emitted both LCP entries with the same startTime. web-vitals only
calls its callback when the LCP value changes, so the handlers never got
the image entry and window._LCP stayed at 68.

Put the button into its own block, so the image is the only LCP
candidate. On Linux (Playwright v1.63.0 image) the test failed 3 of 60
and 3 of 120 runs before, and passed 120 of 120 after.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .../suites/tracing/metrics/handlers-lcp/template.html         | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/dev-packages/browser-integration-tests/suites/tracing/metrics/handlers-lcp/template.html b/dev-packages/browser-integration-tests/suites/tracing/metrics/handlers-lcp/template.html
index ff4754b3ebb6..dc24329539fe 100644
--- a/dev-packages/browser-integration-tests/suites/tracing/metrics/handlers-lcp/template.html
+++ b/dev-packages/browser-integration-tests/suites/tracing/metrics/handlers-lcp/template.html
@@ -6,6 +6,8 @@
   <body>
     <div id="content"></div>
     <img src="https://sentry-test-site.example/path/to/image.png" />
-    <button type="button" aria-label="Finalize LCP"></button>
+    <!-- Keeps the button off the image's line: whitespace between inline elements is painted as text, which can
+         become an LCP entry in the same frame as the image and hide the image from the LCP handlers. -->
+    <div><button type="button" aria-label="Finalize LCP"></button></div>
   </body>
 </html>