🔊 Add feature flags to telemetry events

packages/core/src/domain/configuration/experimentalFeatures.ts

@@ -5,29 +5,29 @@
  * So keep in mind that in certain configurations, your experimental feature flag may affect other products.
  */
 
-let enabledExperimentalFeatures: Set<string>
+let enabledExperimentalFeatures: string[] = []
 
 export function updateExperimentalFeatures(enabledFeatures: string[] | undefined): void {
   // Safely handle external data
   if (!Array.isArray(enabledFeatures)) {
     return
   }
 
-  if (!enabledExperimentalFeatures) {
-    enabledExperimentalFeatures = new Set(enabledFeatures)
-  }
-
   enabledFeatures
     .filter((flag) => typeof flag === 'string')
     .forEach((flag: string) => {
-      enabledExperimentalFeatures.add(flag)
+      if (!enabledExperimentalFeatures.includes(flag)) enabledExperimentalFeatures.push(flag)
     })
 }
 
 export function isExperimentalFeatureEnabled(featureName: string): boolean {
-  return !!enabledExperimentalFeatures && enabledExperimentalFeatures.has(featureName)
+  return enabledExperimentalFeatures.includes(featureName)
 }
 
 export function resetExperimentalFeatures(): void {
-  enabledExperimentalFeatures = new Set()
+  enabledExperimentalFeatures = []
+}
+
+export function getExperimentalFeatures(): string[] {
+  return enabledExperimentalFeatures
 }

packages/core/src/domain/configuration/index.ts

@@ -10,5 +10,6 @@ export {
   isExperimentalFeatureEnabled,
   updateExperimentalFeatures,
   resetExperimentalFeatures,
+  getExperimentalFeatures,
 } from './experimentalFeatures'
 export * from './intakeSites'

packages/core/src/domain/telemetry/telemetry.spec.ts

@@ -1,7 +1,7 @@
 import type { StackTrace } from '@datadog/browser-core'
 import { callMonitored } from '../../tools/monitor'
 import type { Configuration } from '../configuration'
-import { INTAKE_SITE_US1, INTAKE_SITE_US1_FED } from '../configuration'
+import { updateExperimentalFeatures, INTAKE_SITE_US1, INTAKE_SITE_US1_FED } from '../configuration'
 import { resetTelemetry, startTelemetry, scrubCustomerFrames, formatError } from './telemetry'
 
 function startAndSpyTelemetry(configuration?: Partial<Configuration>) {
@@ -31,6 +31,16 @@ describe('telemetry', () => {
     expect(notifySpy).toHaveBeenCalledTimes(1)
   })
 
+  it('should contains feature flags', () => {
+    updateExperimentalFeatures(['foo'])
+    const { notifySpy } = startAndSpyTelemetry()
+    callMonitored(() => {
+      throw new Error('message')
+    })
+
+    expect(notifySpy.calls.mostRecent().args[0].experimental_features).toEqual(['foo'])
+  })
+
   describe('telemetry context', () => {
     it('should be added to telemetry events', () => {
       const { telemetry, notifySpy } = startAndSpyTelemetry()

packages/core/src/domain/telemetry/telemetry.ts

@@ -3,7 +3,7 @@ import { ConsoleApiName } from '../../tools/display'
 import { toStackTraceString } from '../../tools/error'
 import { assign, combine, jsonStringify, performDraw, includes, startsWith } from '../../tools/utils'
 import type { Configuration } from '../configuration'
-import { INTAKE_SITE_STAGING, INTAKE_SITE_US1_FED } from '../configuration'
+import { getExperimentalFeatures, INTAKE_SITE_STAGING, INTAKE_SITE_US1_FED } from '../configuration'
 import type { StackTrace } from '../tracekit'
 import { computeStackTrace } from '../tracekit'
 import { Observable } from '../../tools/observable'
@@ -80,6 +80,7 @@ export function startTelemetry(configuration: Configuration): Telemetry {
           format_version: 2 as const,
         },
         telemetry: event as any, // https://github.com/microsoft/TypeScript/issues/48457
+        experimental_features: getExperimentalFeatures(),
       },
       contextProvider !== undefined ? contextProvider() : {}
     )