fix: incorrect standard swap gas fee estimation (#28127)

## **Description**

Fix incorrect non-smart gas fee estimations due to the use of an empty
estimated base fee.

[![Open in GitHub
Codespaces](https://github.com/codespaces/badge.svg)](https://codespaces.new/MetaMask/metamask-extension/pull/28127?quickstart=1)

## **Related issues**

Fixes: #28088 

## **Manual testing steps**

See issue.

## **Screenshots/Recordings**

### **Before**

### **After**

<img width="354" alt="Smart"
src="https://github.com/user-attachments/assets/c1c604d3-9b03-4e4f-b819-9c21f230f789">

<img width="353" alt="Standard"
src="https://github.com/user-attachments/assets/47acd4d1-c618-4d61-afdc-65ce827454a2">

## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I’ve included tests if applicable
- [x] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

ui/pages/swaps/prepare-swap-page/review-quote.js

@@ -257,7 +257,8 @@ export default function ReviewQuote({ setReceiveToAmount }) {
   );
   const smartTransactionFees = useSelector(getSmartTransactionFees, isEqual);
   const swapsNetworkConfig = useSelector(getSwapsNetworkConfig, shallowEqual);
-  const { estimatedBaseFee = '0' } = useGasFeeEstimates();
+  const { gasFeeEstimates: networkGasFeeEstimates } = useGasFeeEstimates();
+  const { estimatedBaseFee = '0' } = networkGasFeeEstimates ?? {};
 
   const gasFeeEstimates = useAsyncResult(async () => {
     if (!networkAndAccountSupports1559) {

ui/pages/swaps/prepare-swap-page/review-quote.test.js

@@ -10,18 +10,26 @@ import {
 } from '../../../../test/jest';
 import { CHAIN_IDS } from '../../../../shared/constants/network';
 import { getSwap1559GasFeeEstimates } from '../swaps.util';
+import { getNetworkConfigurationByNetworkClientId } from '../../../store/actions';
 import ReviewQuote from './review-quote';
 
 jest.mock(
   '../../../components/ui/info-tooltip/info-tooltip-icon',
   () => () => '<InfoTooltipIcon />',
 );
 
+jest.mock('../../../store/actions', () => ({
+  ...jest.requireActual('../../../store/actions'),
+  getNetworkConfigurationByNetworkClientId: jest.fn(),
+}));
+
 jest.mock('../swaps.util', () => ({
   ...jest.requireActual('../swaps.util'),
   getSwap1559GasFeeEstimates: jest.fn(),
 }));
 
+const ESTIMATED_BASE_FEE_MOCK = '1234';
+
 const middleware = [thunk];
 const createProps = (customProps = {}) => {
   return {
@@ -31,6 +39,15 @@ const createProps = (customProps = {}) => {
 };
 
 describe('ReviewQuote', () => {
+  const getNetworkConfigurationByNetworkClientIdMock = jest.mocked(
+    getNetworkConfigurationByNetworkClientId,
+  );
+
+  beforeEach(() => {
+    jest.resetAllMocks();
+    getNetworkConfigurationByNetworkClientIdMock.mockResolvedValue(undefined);
+  });
+
   const getSwap1559GasFeeEstimatesMock = jest.mocked(
     getSwap1559GasFeeEstimates,
   );
@@ -210,5 +227,45 @@ describe('ReviewQuote', () => {
       expect(getByText('Max fee:')).toBeInTheDocument();
       expect(getByText('$8.15')).toBeInTheDocument();
     });
+
+    it('extracts estimated base fee from network gas fee estimates', async () => {
+      getNetworkConfigurationByNetworkClientIdMock.mockResolvedValueOnce({
+        chainId: CHAIN_IDS.MAINNET,
+      });
+
+      smartDisabled1559State.metamask.gasFeeEstimatesByChainId = {
+        [CHAIN_IDS.MAINNET]: {
+          gasFeeEstimates: {
+            estimatedBaseFee: ESTIMATED_BASE_FEE_MOCK,
+          },
+        },
+      };
+
+      getSwap1559GasFeeEstimatesMock.mockResolvedValueOnce({
+        estimatedBaseFee: '0x1',
+        tradeGasFeeEstimates: {
+          maxFeePerGas: '0x2',
+          maxPriorityFeePerGas: '0x3',
+          baseAndPriorityFeePerGas: '0x123456789123',
+        },
+        approveGasFeeEstimates: undefined,
+      });
+
+      const store = configureMockStore(middleware)(smartDisabled1559State);
+      const props = createProps();
+
+      renderWithProvider(<ReviewQuote {...props} />, store);
+
+      await act(() => {
+        // Intentionally empty
+      });
+
+      expect(getSwap1559GasFeeEstimatesMock).toHaveBeenCalledWith(
+        expect.any(Object),
+        null,
+        ESTIMATED_BASE_FEE_MOCK,
+        CHAIN_IDS.MAINNET,
+      );
+    });
   });
 });