Jest mocking does not affect calls within the same module

from Jest Memo Mocking Jest does not affect calls in the same module MyModule.ts

export const A = () => "old value";
export const callA = () => A();

test.ts

test("render", () => {
  jest.spyOn(MyModule, "A").mockImplementation(() => {
    return "new value";
  });
  expect(MyModule.callA()).toBe("new value");

result

Error: expect(received).toBe(expected) // Object.is equality

Expected: "new value"
Received: "old value"

It is convenient to be able to replace a specific function in a module with another process in one line, but if it is called from a function in the same module, it is a source of confusion If it is indeed correct to replace A with a mock, then there should be a module boundary between callA and A (OK1), and if callA and A are so tightly coupled that it is not appropriate to separate them into separate modules, then it is not A that should be replaced with a mock (OK2), is it?

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