test: add coverage for TokenBalancesPoller isolation and AssetPollingContext memoization

Agent-Logs-Url: https://github.com/MetaMask/metamask-extension/sessions/c94cdb5a-1d8d-41e0-b2cc-4060a80f5f24

Co-authored-by: DDDDDanica <12678455+DDDDDanica@users.noreply.github.com>

Author: Copilot

ui/components/multichain/account-overview/account-overview-tabs.test.tsx

@@ -10,12 +10,17 @@ import {
   MetaMetricsEventName,
 } from '../../../../shared/constants/metametrics';
 import { CHAIN_IDS } from '../../../../shared/constants/network';
+import { useTokenBalances } from '../../../hooks/useTokenBalances';
 import { AccountOverviewTabs } from './account-overview-tabs';
 
 jest.mock('../../../store/actions', () => ({
   setDefaultHomeActiveTabName: jest.fn(),
 }));
 
+jest.mock('../../../hooks/useTokenBalances', () => ({
+  useTokenBalances: jest.fn(),
+}));
+
 jest.mock('../../app/assets/asset-list', () => ({
   // eslint-disable-next-line @typescript-eslint/naming-convention
   __esModule: true,
@@ -46,6 +51,11 @@ jest.mock('../../app/perps/perps-tab', () => ({
   PerpsTab: () => <div data-testid="perps-tab-mock">PerpsTab</div>,
 }));
 
+beforeEach(() => {
+  jest.clearAllMocks();
+  (useTokenBalances as jest.Mock).mockReturnValue({ tokenBalances: {} });
+});
+
 describe('AccountOverviewTabs - event metrics', () => {
   const mockTrackEvent = jest.fn();
   const mockMetaMetricsContext = {
@@ -55,10 +65,6 @@ describe('AccountOverviewTabs - event metrics', () => {
     onboardingParentContext: { current: null },
   };
 
-  beforeEach(() => {
-    jest.clearAllMocks();
-  });
-
   it('includes network_filter property with both EVM and non-EVM networks in CAIP format', () => {
     const store = configureStore({
       metamask: {
@@ -107,3 +113,39 @@ describe('AccountOverviewTabs - event metrics', () => {
     });
   });
 });
+
+describe('AccountOverviewTabs - TokenBalancesPoller', () => {
+  it('polls token balances for the enabled EVM chain IDs', () => {
+    const store = configureStore({
+      metamask: {
+        ...mockState.metamask,
+        enabledNetworkMap: {
+          eip155: {
+            [CHAIN_IDS.MAINNET]: true,
+            [CHAIN_IDS.POLYGON]: true,
+          },
+        },
+      },
+    });
+
+    renderWithProvider(
+      <AccountOverviewTabs
+        showTokens={true}
+        showNfts={false}
+        showActivity={false}
+        setBasicFunctionalityModalOpen={jest.fn()}
+        onSupportLinkClick={jest.fn()}
+      />,
+      store,
+    );
+
+    expect(useTokenBalances).toHaveBeenCalledWith(
+      expect.objectContaining({
+        chainIds: expect.arrayContaining([
+          CHAIN_IDS.MAINNET,
+          CHAIN_IDS.POLYGON,
+        ]),
+      }),
+    );
+  });
+});

ui/contexts/assetPolling.test.tsx

@@ -1,4 +1,4 @@
-import React from 'react';
+import React, { useContext, useEffect } from 'react';
 import { render, screen } from '@testing-library/react';
 import '@testing-library/jest-dom';
 import * as redux from 'react-redux';
@@ -9,7 +9,11 @@ import useTokenListPolling from '../hooks/useTokenListPolling';
 import useStaticTokensPollingHook from '../hooks/useStaticTokensPolling';
 import useDeFiPolling from '../hooks/defi/useDeFiPolling';
 import useMultichainAssetsRatesPolling from '../hooks/useMultichainAssetsRatesPolling';
-import { AssetPollingProvider } from './assetPolling';
+import {
+  AssetPollingContext,
+  AssetPollingContextValue,
+  AssetPollingProvider,
+} from './assetPolling';
 
 jest.mock('../hooks/useCurrencyRatePolling');
 jest.mock('../hooks/useTokenRatesPolling');
@@ -97,4 +101,35 @@ describe('AssetPollingProvider', () => {
       expect(mockUseMultichainAssetsRatesPolling).not.toHaveBeenCalled();
     });
   });
+
+  describe('context value memoization', () => {
+    it('provides a stable context value object across re-renders', () => {
+      jest.spyOn(redux, 'useSelector').mockReturnValue(false);
+
+      const capturedValues: AssetPollingContextValue[] = [];
+
+      const TestConsumer = () => {
+        const ctx = useContext(AssetPollingContext);
+        useEffect(() => {
+          capturedValues.push(ctx);
+        });
+        return null;
+      };
+
+      const { rerender } = render(
+        <AssetPollingProvider>
+          <TestConsumer />
+        </AssetPollingProvider>,
+      );
+
+      rerender(
+        <AssetPollingProvider>
+          <TestConsumer />
+        </AssetPollingProvider>,
+      );
+
+      expect(capturedValues.length).toBeGreaterThanOrEqual(2);
+      expect(capturedValues[0]).toBe(capturedValues[1]);
+    });
+  });
 });