ignore setup mock for one file - node.js

Question

I have a decorator that I use on a lot of my methods. To not have to mock it each time, I have added a mock on jest.setup.js:
jest.mock('src/something', () => {
someMethod: jest.fn.mockImplementation(/*some implementation*/)
})
This works fine, but now I want to unit test this one method (the someMethod in this example) and I can't, since it brings up the mock. How can I ignore this mock for only this file/test?

Answer 1

You can use jest.unmock(moduleName) in the test file of a module. So that your module under test will use the real module rather than the mocked version.
Let's see an example:
./src/stackoverflow/73129547/something.ts:
export const someMethod = () => 1;
This is the module we want to mock.
./jest.setup.js:
jest.setTimeout(5 * 1000);
jest.mock('./stackoverflow/73129547/something', () => ({
someMethod: jest.fn().mockReturnValue(0),
}));
jest.config.js:
module.exports = {
preset: 'ts-jest/presets/js-with-ts',
testEnvironment: 'jsdom',
setupFilesAfterEnv: ['./jest.setup.js'],
};
We set up the mock using jest.mock() in the jest.setup.js file. So that every module under test will use the mocked version of this module.
Suppose our project has two modules: a.ts and b.ts, they use the someMethod exported from the something module.
./src/stackoverflow/73129547/a.ts:
import { someMethod } from './something';
export const a = someMethod;
./src/stackoverflow/73129547/b.ts:
import { someMethod } from './something';
export const b = someMethod;
The test suites of a and b modules:
./src/stackoverflow/73129547/a.test.ts:
import { a } from './a';
describe('73129547 - a', () => {
test('should pass', () => {
expect(a()).toBe(0);
});
});
./src/stackoverflow/73129547/b.test.ts:
import { b } from "./b";
describe('73129547 - b', () => {
test('should pass', () => {
expect(b()).toBe(0);
});
});
Test result:
PASS stackoverflow/73129547/b.test.ts
PASS stackoverflow/73129547/a.test.ts (9.829 s)
Test Suites: 2 passed, 2 total
Tests: 2 passed, 2 total
Snapshots: 0 total
Time: 10.681 s
As you can see the expected execution result. Both the a and b modules use the mocked someMethod which has a mock return value: 0.
Now, we want to test the someMethod of the something module, we should test the real someMethod rather than the mocked one. Test mock implementations make no sense.
./src/stackoverflow/73129547/something.test.ts:
import { someMethod } from './something';
jest.unmock('./something');
describe('73129547 - something', () => {
test('should pass', () => {
expect(someMethod()).toBe(1);
});
});
Test result:
PASS stackoverflow/73129547/a.test.ts
PASS stackoverflow/73129547/b.test.ts
PASS stackoverflow/73129547/something.test.ts
Test Suites: 3 passed, 3 total
Tests: 3 passed, 3 total
Snapshots: 0 total
Time: 1.955 s, estimated 14 s
As you can see, the return value of real someMethod is 1. jest.unmock(moduleName) will unmock the module and return the real module.