I have following two modules.

// exchange.ts

export async function fetchBalances(exchangeIds: string[]): Promise<ExchangeBalance> { /* ... */}

// normalizer.ts

import { fetchBalances } from './exchange';

export async function scaleFactor() {
  const balances = await fetchBalances([...]);
  // ....
}

I am trying to mock fetchBalances of exchange when testing normalizer as follows:

// normalizer.test.ts

beforeEach(() => {
  jest.resetModules();
});

async function mockExchange() {
  jest.doMock('../src/exchange', () => {
    return {
      __esModule: true,

      fetchBalances: async (exchangeIds: string[]): Promise<ExchangeBalance> => {
        return {/* ... */};
      }
    };
  });

  return (await import('../src/exchange'));
}

test('returns 1', async () => {
    // 1
    const moduleName = await mockExchange();
    console.log(await moduleName.fetchBalances([...]));

    // 2
    const scaleFactor = await scaleFactor();
    expect(scaleFactor).toEqual(1);
});

1. Direct call to moduleName uses mock & doesnt call API. All good here.
2. However, calls to scaleFactor does not use mock & runs real implementation of fetchBalances.

How can I make normalizer to use mocks of fetchBalances ?