feat: warn that payload filtering has no effect with FDv2

packages/shared/sdk-client/__tests__/datasource/FDv2DataManagerBase.test.ts

@@ -1153,3 +1153,35 @@ it('populates polling and streaming config in the factory context', async () =>
 
   manager.close();
 });
+
+it('warns when a payload filter key is configured', () => {
+  const config = makeConfig({
+    serviceEndpoints: new ServiceEndpoints(
+      'https://stream',
+      'https://poll',
+      'https://events',
+      '/bulk',
+      '/diagnostic',
+      true,
+      'microservice-1',
+    ),
+  });
+
+  const manager = createFDv2DataManagerBase(makeBaseConfig({ config }));
+
+  expect(config.logger.warn).toHaveBeenCalledWith(
+    expect.stringContaining('Payload filtering is not supported with the FDv2 data system'),
+  );
+
+  manager.close();
+});
+
+it('does not warn when no payload filter key is configured', () => {
+  const config = makeConfig();
+
+  const manager = createFDv2DataManagerBase(makeBaseConfig({ config }));
+
+  expect(config.logger.warn).not.toHaveBeenCalled();
+
+  manager.close();
+});

packages/shared/sdk-client/src/api/LDOptions.ts

@@ -249,6 +249,9 @@ export interface LDOptions {
    * This payload filter key only applies to the default streaming and polling data sources. It will not affect
    * TestData or FileData data sources, nor will it be applied to any data source provided through the featureStore
    * config property.
+   *
+   * Payload filtering is not supported with the FDv2 data system, so this key has no effect on requests made by
+   * FDv2 data sources.
    */
   payloadFilterKey?: string;
 

packages/shared/sdk-client/src/datasource/FDv2DataManagerBase.ts

@@ -137,6 +137,13 @@ export function createFDv2DataManagerBase(
   } = baseConfig;
 
   const { logger } = config;
+
+  if (config.serviceEndpoints.payloadFilterKey !== undefined) {
+    logger?.warn(
+      `${logTag} Payload filtering is not supported with the FDv2 data system; the configured payload filter has no effect on FDv2 requests`,
+    );
+  }
+
   const statusManager: DataSourceStatusManager = createDataSourceStatusManager(emitter);
   const endpoints = fdv2Endpoints();
 

packages/shared/sdk-server/__tests__/LDClientImpl.payloadFilter.test.ts

@@ -0,0 +1,70 @@
+import { LDLogger } from '@launchdarkly/js-sdk-common';
+
+import { LDOptions } from '../src/api/options/LDOptions';
+import LDClientImpl from '../src/LDClientImpl';
+import { createBasicPlatform } from './createBasicPlatform';
+
+describe('given a client using the FDv2 data system', () => {
+  const callbacks = {
+    onFailed: jest.fn(),
+    onError: jest.fn(),
+    onReady: jest.fn(),
+    onUpdate: jest.fn(),
+    hasEventListeners: jest.fn(),
+  };
+  let platform: any;
+  let logger: LDLogger;
+  let client: LDClientImpl;
+
+  function makeOptions(overrides: LDOptions = {}): LDOptions {
+    return {
+      sendEvents: false,
+      diagnosticOptOut: true,
+      logger,
+      dataSystem: {
+        dataSource: {
+          dataSourceOptionsType: 'custom',
+          initializers: [],
+          synchronizers: [],
+        },
+      },
+      ...overrides,
+    };
+  }
+
+  beforeEach(() => {
+    platform = createBasicPlatform();
+    logger = {
+      error: jest.fn(),
+      warn: jest.fn(),
+      info: jest.fn(),
+      debug: jest.fn(),
+    };
+  });
+
+  afterEach(() => {
+    client?.close();
+    jest.resetAllMocks();
+  });
+
+  it('warns when a payload filter key is configured', () => {
+    client = new LDClientImpl(
+      'sdk-key',
+      platform,
+      makeOptions({ payloadFilterKey: 'microservice-1' }),
+      callbacks,
+    );
+
+    expect(logger.warn).toHaveBeenCalledWith(
+      expect.stringContaining('Payload filtering is not supported with the FDv2 data system'),
+    );
+  });
+
+  it('does not warn when no payload filter key is configured', () => {
+    client = new LDClientImpl('sdk-key', platform, makeOptions(), callbacks);
+
+    expect(logger.warn).not.toHaveBeenCalledWith(
+      expect.stringContaining('Payload filtering is not supported'),
+    );
+  });
+});

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

@@ -302,6 +302,13 @@ function constructFDv2(
   }
 
   const { logger } = config;
+
+  if (config.payloadFilterKey !== undefined) {
+    logger?.warn(
+      'Payload filtering is not supported with the FDv2 data system; the configured payload filter has no effect on FDv2 requests',
+    );
+  }
+
   const baseHeaders = defaultHeaders(
     sdkKey,
     platform.info,

packages/shared/sdk-server/src/api/options/LDOptions.ts

@@ -328,6 +328,9 @@ export interface LDOptions {
    * This payload filter key only applies to the default streaming and polling data sources. It will not affect
    * TestData or FileData data sources, nor will it be applied to any data source provided through the featureStore
    * config property.
+   *
+   * Payload filtering is not supported with the FDv2 data system, so this key has no effect on requests made by
+   * FDv2 data sources.
    */
   payloadFilterKey?: string;