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test(browser): Keep whitespace text out of the handlers-lcp page - #25280
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Nice find! Tbh, not fully sure if asserting on the exact size is a good idea but if it differed by so much (68 vs. 107400) any "is in range" check would have failed here.
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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>
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This moves the button of the
handlers-lcptest page into its own block, so the image is the only LCP candidate.Why
The space between the inline
<img>and<button>was painted as a text run in<body>(68 px²). When it painted in the same frame as the image, Chromium gave both LCP entries the samestartTime. web-vitals calls its callback only when the LCP value changes, so the handlers never got the image entry, andwindow._LCPstayed at 68.On Linux (Playwright v1.63.0 image, 8 workers), 3 of 60 and 3 of 120 runs failed before this change. After it, 120 of 120 passed.
Failed on CI: https://github.com/getsentry/sentry-javascript/actions/runs/38217884500/job/114713949461