fix: merge context to preserve plugin injected properties (segmentio#487)

Author: oscb

example/ios/Podfile.lock

@@ -466,4 +466,4 @@ SPEC CHECKSUMS:
 
 PODFILE CHECKSUM: 0c7eb82d495ca56953c50916b7b49e7512632eb6
 
-COCOAPODS: 1.11.2
+COCOAPODS: 1.11.3

packages/core/package.json

@@ -47,6 +47,7 @@
   "dependencies": {
     "@react-native-async-storage/async-storage": "^1.15.17",
     "@segment/sovran-react-native": "^0.2.6",
+    "deepmerge": "^4.2.2",
     "js-base64": "^3.7.2",
     "nanoid": "^3.1.25"
   },

packages/core/src/__tests__/internal/checkInstalledVersion.test.ts

@@ -3,6 +3,7 @@ import { getMockLogger } from '../__helpers__/mockLogger';
 import * as context from '../../context';
 import { MockSegmentStore } from '../__helpers__/mockSegmentStore';
 import { Context, EventType } from '../../types';
+import deepmerge from 'deepmerge';
 
 jest
   .spyOn(Date.prototype, 'toISOString')
@@ -161,4 +162,47 @@ describe('internal #checkInstalledVersion', () => {
       type: EventType.TrackEvent,
     });
   });
+
+  it('merges context and preserves context injected by plugins during configure', async () => {
+    const injectedContextByPlugins = {
+      device: {
+        adTrackingEnabled: true,
+        advertisingId: 'mock-advertising-id',
+      },
+    };
+
+    const store = new MockSegmentStore({
+      context: {
+        ...currentContext,
+        ...injectedContextByPlugins,
+      },
+    });
+
+    client = new SegmentClient({
+      ...clientArgs,
+      store,
+    });
+
+    const newContext = {
+      ...currentContext, // Just adding the full object to prevent TS complaining about missing properties
+      app: {
+        version: '1.5',
+        build: '2',
+        name: 'Test',
+        namespace: 'Test',
+      },
+      device: {
+        manufacturer: 'Apple',
+        model: 'iPhone',
+        name: 'iPhone',
+        type: 'iOS',
+      },
+    };
+    jest.spyOn(context, 'getContext').mockResolvedValueOnce(newContext);
+    await client.init();
+
+    expect(store.context.get()).toEqual(
+      deepmerge(newContext, injectedContextByPlugins)
+    );
+  });
 });

packages/core/src/analytics.ts

@@ -1,7 +1,7 @@
-import { AppState, AppStateStatus } from 'react-native';
 import type { Unsubscribe } from '@segment/sovran-react-native';
+import deepmerge from 'deepmerge';
+import { AppState, AppStateStatus } from 'react-native';
 import { getContext } from './context';
-
 import {
   applyRawEventData,
   createAliasEvent,
@@ -566,7 +566,8 @@ export class SegmentClient {
 
     const previousContext = this.store.context.get();
 
-    this.store.context.set(context);
+    // Only overwrite the previous context values to preserve any values that are added by enrichment plugins like IDFA
+    this.store.context.set(deepmerge(previousContext ?? {}, context));
 
     if (!this.config.trackAppLifecycleEvents) {
       return;