fix: missing events bundled dep (#660)

Fixes: #659

This PR fixes an issue created with [this
change](#650), which removed
the `events` polyfill package from `@openfeature/core` where is wasn't
always needed (see that issue for details). The problem was that we
still imported `events` in the `@openfeature/core` module, but can't use
the `events` bundled in the `@openfeature/web-sdk` since the bundled
package there isn't accessible from imports in `@openfeature/core`.

This PR _**removes all imports of `events`**_ from `@openfeature/core`,
and instead only imports types. Imports of `events` only now occur in
the web-sdk (where it's bundled) and server-sdk (where it's made
available by the node runtime), not in the common module.

Unfortunately this issue was a bit tough to track down, because `events`
is VERY common, and lots of bundlers, etc will add it, so it's
frequently available "accidentally".

Thanks to @juanparadox for the report.

---------

Signed-off-by: Todd Baert <[email protected]>

Author: toddbaert

packages/client/src/client/open-feature-client.ts

@@ -11,7 +11,6 @@ import {
   JsonValue,
   Logger,
   OpenFeatureError,
-  OpenFeatureEventEmitter,
   ProviderEvents,
   ProviderStatus,
   ResolutionDetails,
@@ -21,6 +20,7 @@ import {
 import { FlagEvaluationOptions } from '../evaluation';
 import { OpenFeature } from '../open-feature';
 import { Provider } from '../provider';
+import { InternalEventEmitter } from '../events/internal/internal-event-emitter';
 import { Client } from './client';
 
 type OpenFeatureClientOptions = {
@@ -36,7 +36,7 @@ export class OpenFeatureClient implements Client {
     // functions are passed here to make sure that these values are always up to date,
     // and so we don't have to make these public properties on the API class.
     private readonly providerAccessor: () => Provider,
-    private readonly emitterAccessor: () => OpenFeatureEventEmitter,
+    private readonly emitterAccessor: () => InternalEventEmitter,
     private readonly globalLogger: () => Logger,
     private readonly options: OpenFeatureClientOptions
   ) {}

packages/client/src/events/index.ts

@@ -0,0 +1 @@
+export * from './open-feature-event-emitter';

packages/client/src/events/internal/internal-event-emitter.ts

@@ -0,0 +1,8 @@
+import { CommonEventDetails, GenericEventEmitter } from '@openfeature/core';
+
+/**
+ * The InternalEventEmitter is not exported publicly and should only be used within the SDK. It extends the
+ * OpenFeatureEventEmitter to include additional properties that can be included
+ * in the event details.
+ */
+export abstract class InternalEventEmitter extends GenericEventEmitter<CommonEventDetails> {};

packages/client/src/events/open-feature-event-emitter.ts

@@ -0,0 +1,20 @@
+import { GenericEventEmitter } from '@openfeature/core';
+import EventEmitter from 'events';
+
+/**
+ * The OpenFeatureEventEmitter can be used by provider developers to emit
+ * events at various parts of the provider lifecycle.
+ *
+ * NOTE: Ready and error events are automatically emitted by the SDK based on
+ * the result of the initialize method.
+ */
+export class OpenFeatureEventEmitter extends GenericEventEmitter {
+  protected readonly eventEmitter = new EventEmitter({ captureRejections: true });
+
+  constructor() {
+    super();
+    this.eventEmitter.on('error', (err) => {
+      this._logger?.error('Error running event handler:', err);
+    });
+  }
+}

packages/client/src/index.ts

@@ -1,6 +1,6 @@
-import 'events'; // we need this to trigger the bundling of the browser events module: https://www.npmjs.com/package/events
 export * from './client';
 export * from './provider';
 export * from './evaluation';
 export * from './open-feature';
+export * from './events';
 export * from '@openfeature/core';

packages/client/src/open-feature.ts

@@ -1,6 +1,7 @@
 import { EvaluationContext, ManageContext, OpenFeatureCommonAPI } from '@openfeature/core';
 import { Client, OpenFeatureClient } from './client';
 import { NOOP_PROVIDER, Provider } from './provider';
+import { OpenFeatureEventEmitter } from './events';
 
 // use a symbol as a key for the global singleton
 const GLOBAL_OPENFEATURE_API_KEY = Symbol.for('@openfeature/web-sdk/api');
@@ -11,7 +12,9 @@ type OpenFeatureGlobal = {
 const _globalThis = globalThis as OpenFeatureGlobal;
 
 export class OpenFeatureAPI extends OpenFeatureCommonAPI<Provider> implements ManageContext<Promise<void>> {
+  protected _events = new OpenFeatureEventEmitter();
   protected _defaultProvider: Provider = NOOP_PROVIDER;
+  protected _createEventEmitter = () => new OpenFeatureEventEmitter();
 
   // eslint-disable-next-line @typescript-eslint/no-empty-function
   private constructor() {

packages/client/test/events.spec.ts

@@ -9,7 +9,7 @@ import {
   ProviderMetadata,
   ProviderStatus,
   ResolutionDetails,
-  StaleEvent,
+  StaleEvent
 } from '../src';
 
 const TIMEOUT = 1000;

packages/client/tsconfig.json

@@ -28,7 +28,9 @@
     // "rootDir": "./",                                  /* Specify the root folder within your source files. */
     "moduleResolution": "node", /* Specify how TypeScript looks up a file from a given module specifier. */
     // "baseUrl": "./",                                  /* Specify the base directory to resolve non-relative module names. */
-    // "paths": {},                                      /* Specify a set of entries that re-map imports to additional lookup locations. */
+    "paths": {
+      "@openfeature/core": [ "../shared/src" ]
+    },                                                   /* Specify a set of entries that re-map imports to additional lookup locations. */
     // "rootDirs": [],                                   /* Allow multiple folders to be treated as one when resolving modules. */
     // "typeRoots": [],                                  /* Specify multiple folders that act like `./node_modules/@types`. */
     // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */

packages/server/src/client/open-feature-client.ts

@@ -8,7 +8,6 @@ import {
   FlagValueType,
   Hook,
   HookContext,
-  InternalEventEmitter,
   JsonValue,
   Logger,
   ManageContext,
@@ -23,6 +22,7 @@ import { FlagEvaluationOptions } from '../evaluation';
 import { OpenFeature } from '../open-feature';
 import { Provider } from '../provider';
 import { Client } from './client';
+import { InternalEventEmitter } from '../events/internal/internal-event-emitter';
 
 type OpenFeatureClientOptions = {
   name?: string;

packages/server/src/events/index.ts

@@ -0,0 +1 @@
+export * from './open-feature-event-emitter';