fix: Prerequisites should not trigger hooks. (#628)

Author: kinyoklion

packages/shared/sdk-client/__tests__/LDClientImpl.hooks.test.ts

@@ -3,6 +3,8 @@ import { AutoEnvAttributes } from '@launchdarkly/js-sdk-common';
 import { Hook, HookMetadata } from '../src/api';
 import LDClientImpl from '../src/LDClientImpl';
 import { createBasicPlatform } from './createBasicPlatform';
+import * as mockResponseJson from './evaluation/mockResponse.json';
+import { MockEventSource } from './streaming/LDClientImpl.mocks';
 import { makeTestDataManagerFactory } from './TestDataManager';
 
 it('should use hooks registered during configuration', async () => {
@@ -239,3 +241,70 @@ it('should execute both initial hooks and hooks added using addHook', async () =
     },
   );
 });
+
+it('should not execute hooks for prerequisite evaluations', async () => {
+  const testHook: Hook = {
+    beforeEvaluation: jest.fn(),
+    afterEvaluation: jest.fn(),
+    beforeIdentify: jest.fn(),
+    afterIdentify: jest.fn(),
+    getMetadata(): HookMetadata {
+      return {
+        name: 'test hook',
+      };
+    },
+  };
+
+  const platform = createBasicPlatform();
+  let mockEventSource: MockEventSource;
+  const simulatedEvents = [{ data: JSON.stringify(mockResponseJson) }];
+  platform.requests.createEventSource.mockImplementation(
+    (streamUri: string = '', options: any = {}) => {
+      mockEventSource = new MockEventSource(streamUri, options);
+      mockEventSource.simulateEvents('put', simulatedEvents);
+      return mockEventSource;
+    },
+  );
+
+  const factory = makeTestDataManagerFactory('sdk-key', platform);
+  const client = new LDClientImpl(
+    'sdk-key',
+    AutoEnvAttributes.Disabled,
+    platform,
+    {
+      sendEvents: false,
+      hooks: [testHook],
+      logger: {
+        debug: jest.fn(),
+        info: jest.fn(),
+        warn: jest.fn(),
+        error: jest.fn(),
+      },
+    },
+    factory,
+  );
+
+  await client.identify({ key: 'user-key' });
+  await client.variation('has-prereq-depth-1', false);
+
+  expect(testHook.beforeEvaluation).toHaveBeenCalledTimes(1);
+
+  expect(testHook.beforeEvaluation).toHaveBeenCalledWith(
+    { context: { key: 'user-key' }, defaultValue: false, flagKey: 'has-prereq-depth-1' },
+    {},
+  );
+
+  expect(testHook.afterEvaluation).toHaveBeenCalledTimes(1);
+
+  expect(testHook.afterEvaluation).toHaveBeenCalledWith(
+    { context: { key: 'user-key' }, defaultValue: false, flagKey: 'has-prereq-depth-1' },
+    {},
+    {
+      reason: {
+        kind: 'FALLTHROUGH',
+      },
+      value: true,
+      variationIndex: 0,
+    },
+  );
+});

packages/shared/sdk-client/src/LDClientImpl.ts

@@ -357,7 +357,7 @@ export default class LDClientImpl implements LDClient {
     }
 
     prerequisites?.forEach((prereqKey) => {
-      this.variation(prereqKey, undefined);
+      this._variationInternal(prereqKey, undefined, this._eventFactoryDefault);
     });
     this._eventProcessor?.sendEvent(
       eventFactory.evalEventClient(