chore(browser): Clean up open handles when running Jest

- 143 from XMLHttpRequest.send
- ~20 from getRequestPerformanceEntry retry timeouts in
  fetch-wrapper-invariants

Author: dustinbyrne

packages/browser/src/__tests__/extensions/replay/external/fetch-wrapper-invariants.test.ts

@@ -40,6 +40,11 @@ function setupWrappedFetch(downstreamFetch: typeof fetch): { wrappedFetch: typeo
 }
 
 describe('fetch wrapper', () => {
+    // Use fake timers to prevent getRequestPerformanceEntry retry timeouts
+    // from keeping the Jest worker alive after tests complete.
+    beforeEach(() => jest.useFakeTimers())
+    afterEach(() => jest.useRealTimers())
+
     describe('does not throw for valid inputs', () => {
         let wrappedFetch: typeof fetch
         let cleanup: () => void

packages/browser/src/__tests__/setup.js

@@ -7,4 +7,10 @@ beforeEach(() => {
     console.warn = (...args) => {
         throw new Error(`Unexpected console.warn: ${args}`)
     }
+
+    // Prevent jsdom XHR requests from creating open handles (TLSWRAP/Timeout)
+    // that keep Jest from exiting. No unit tests need real HTTP responses.
+    if (typeof XMLHttpRequest !== 'undefined') {
+        jest.spyOn(XMLHttpRequest.prototype, 'send').mockImplementation(() => {})
+    }
 })