Add hermetic coverage for service boundaries

web/src/obs.browser.test.ts

@@ -0,0 +1,39 @@
+import { afterEach, expect, test, vi } from 'vitest'
+
+import { installClientErrorReporting } from './observability'
+
+afterEach(() => vi.restoreAllMocks())
+
+test('reports and cleans up', () => {
+  const beacon = vi.spyOn(navigator, 'sendBeacon').mockReturnValue(true)
+  const added = vi.spyOn(window, 'addEventListener')
+  const removed = vi.spyOn(window, 'removeEventListener')
+  const remove = installClientErrorReporting()
+  const error = added.mock.calls.find(([kind]) => kind === 'error')?.[1]
+  const rejection = added.mock.calls.find(
+    ([kind]) => kind === 'unhandledrejection',
+  )?.[1]
+
+  expect(error).toEqual(expect.any(Function))
+  expect(rejection).toEqual(expect.any(Function))
+  ;(error as EventListener)(new Event('error'))
+  ;(rejection as EventListener)(new Event('unhandledrejection'))
+
+  expect(beacon.mock.calls).toEqual([
+    [
+      '/client-errors',
+      JSON.stringify({ kind: 'error', path: window.location.pathname }),
+    ],
+    [
+      '/client-errors',
+      JSON.stringify({
+        kind: 'unhandled_rejection',
+        path: window.location.pathname,
+      }),
+    ],
+  ])
+
+  remove()
+  expect(removed).toHaveBeenCalledWith('error', error)
+  expect(removed).toHaveBeenCalledWith('unhandledrejection', rejection)
+})