How to mock a module with bun:test?

[raulfdm]

Hey folks.

I was considering migrating our company's unit test to use bun to gain some performance but then I didn't find a way of mocking like vi.mock('module-name', ()=>{...}.

I thought about importing the module and using spyOn but this would drastically change my current setup.

Am I missing something?

[roryokane]

It looks like Bun doesn’t support jest.mock or vi.mock yet. See open issue #5394.

[KhalfaniW]

They have implented it in new bun versions according to the ticket #5394

import { expect, test, mock } from "bun:test";
import { main, main2 } from "./module";

test("before", async () => {
  expect(main()).toBe(1);
  expect(main2()).toBe(2);
});

test("after", async () => {
  const mockDependency = () => "mocked";
  mock.module("./module.ts", () => ({ main: mockDependency }));
  expect(main()).toBe("mocked");
  expect(main2()).toBe(2);
});

[constraintAutomaton]

I wonder how can we revert the mock to the original implementation?

[brenodanyel]

Mocks are automatically reset between tests.
https://bun.sh/docs/cli/test#mocks