add integration test for empty string attribute

Author: Lms24

dev-packages/browser-integration-tests/suites/public-api/startSpan/attributes/subject.js

@@ -0,0 +1,11 @@
+async function run() {
+  Sentry.startSpan({ name: 'parent_span' }, () => {
+    Sentry.startSpan({ name: 'child_span', attributes: { someAttribute: '' } }, () => {
+      // whatever a user would do here
+    });
+  });
+}
+
+(async () => {
+  await run();
+})();

dev-packages/browser-integration-tests/suites/public-api/startSpan/attributes/test.ts

@@ -0,0 +1,21 @@
+import { expect } from '@playwright/test';
+
+import { sentryTest } from '../../../../utils/fixtures';
+import {
+  envelopeRequestParser,
+  shouldSkipTracingTest,
+  waitForTransactionRequestOnUrl,
+} from '../../../../utils/helpers';
+
+sentryTest('sends an empty string attribute', async ({ getLocalTestPath, page }) => {
+  if (shouldSkipTracingTest()) {
+    sentryTest.skip();
+  }
+
+  const url = await getLocalTestPath({ testDir: __dirname });
+  const req = await waitForTransactionRequestOnUrl(page, url);
+  const transaction = envelopeRequestParser(req);
+
+  const childSpan = transaction.spans?.[0];
+  expect(childSpan?.data?.someAttribute).toBe('');
+});