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test(browser): Register the LCP handlers in the bundle of the SDK #25263

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Merged
chargome merged 1 commit into from
Oct 12, 2026
Merged

test(browser): Register the LCP handlers in the bundle of the SDK #25263

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30 changes: 30 additions & 0 deletions dev-packages/browser-integration-tests/suites/tracing/metrics/handlers-lcp/init.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,30 @@
import * as Sentry from '@sentry/browser';
import { addLcpInstrumentationHandler } from '@sentry/browser-utils';

window.Sentry = Sentry;

Sentry.init({
dsn: 'https://public@dsn.ingest.sentry.io/1337',
integrations: [Sentry.browserTracingIntegration()],
tracesSampleRate: 1,
});

// Registered in the bundle of the SDK, so the handlers share its LCP observer. A second bundle gets
// a copy of the instrumentation with an observer of its own, whose view of the LCP candidates can
// differ from the SDK's (e.g. a different first-hidden time), which made this test flaky.
addLcpInstrumentationHandler(({ metric }) => {
const entry = metric.entries[metric.entries.length - 1];
window._LCP = entry.size;
});

addLcpInstrumentationHandler(({ metric }) => {
const entry = metric.entries[metric.entries.length - 1];
window._LCP2 = entry.size;
});

window.ADD_HANDLER = () => {
addLcpInstrumentationHandler(({ metric }) => {
const entry = metric.entries[metric.entries.length - 1];
window._LCP3 = entry.size;
});
};
19 changes: 1 addition & 18 deletions dev-packages/browser-integration-tests/suites/tracing/metrics/handlers-lcp/subject.js
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Original file line number Diff line number Diff line change
@@ -1,18 +1 @@
import { addLcpInstrumentationHandler } from '@sentry/browser-utils';

addLcpInstrumentationHandler(({ metric }) => {
const entry = metric.entries[metric.entries.length - 1];
window._LCP = entry.size;
});

addLcpInstrumentationHandler(({ metric }) => {
const entry = metric.entries[metric.entries.length - 1];
window._LCP2 = entry.size;
});

window.ADD_HANDLER = () => {
addLcpInstrumentationHandler(({ metric }) => {
const entry = metric.entries[metric.entries.length - 1];
window._LCP3 = entry.size;
});
};
// The handlers live in `init.js`, see there.
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