account for spaces in baggage header (+adjust test)

Author: Lms24

dev-packages/browser-integration-tests/suites/tracing/request/xhr-with-custom-sentry-headers/subject.js

@@ -3,6 +3,6 @@ const xhr = new XMLHttpRequest();
 xhr.open('GET', 'http://sentry-test-site.example/1');
 xhr.setRequestHeader('X-Test-Header', 'existing-header');
 xhr.setRequestHeader('sentry-trace', '123-abc-1');
-xhr.setRequestHeader('baggage', 'sentry-release=1.1.1');
+xhr.setRequestHeader('baggage', ' sentry-release=1.1.1,  sentry-trace_id=123');
 
 xhr.send();

dev-packages/browser-integration-tests/suites/tracing/request/xhr-with-custom-sentry-headers/test.ts

@@ -20,7 +20,7 @@ sentryTest(
     const requestHeaders = request.headers();
     expect(requestHeaders).toMatchObject({
       'sentry-trace': '123-abc-1',
-      baggage: 'sentry-release=1.1.1',
+      baggage: 'sentry-release=1.1.1,  sentry-trace_id=123',
       'x-test-header': 'existing-header',
     });
   },

packages/browser/src/tracing/request.ts

@@ -431,7 +431,9 @@ function setHeaderOnXhr(
     // eslint-disable-next-line @typescript-eslint/no-non-null-assertion
     xhr.setRequestHeader!('sentry-trace', sentryTraceHeader);
     if (sentryBaggageHeader) {
-      // bail if a pre-existing baggage header is set and already contains sentry values
+      // only add our headers if
+      // - no pre-existing baggage header exists
+      // - or it is set and doesn't yet contain sentry values
       const originalBaggageHeader = originalHeaders?.['baggage'];
       if (!originalBaggageHeader || !baggageHeaderHasSentryValues(originalBaggageHeader)) {
         // From MDN: "If this method is called several times with the same header, the values are merged into one single request header."
@@ -447,7 +449,7 @@ function setHeaderOnXhr(
 }
 
 function baggageHeaderHasSentryValues(baggageHeader: string): boolean {
-  return baggageHeader.split(',').some(value => value.startsWith('sentry-'));
+  return baggageHeader.split(',').some(value => value.trim().startsWith('sentry-'));
 }
 
 function getFullURL(url: string): string | undefined {