描述块内的 jest.setTimeOut() 是否仅将超时应用于描述块内的测试

Question

I am trying to increase the jest timeout for some test cases all inside a describe block.

I found this stackoverflow question where in answer they suggested using jest.setTimeOut(10000) inside test(name, fn) to increase timeout for just that test case.

test('descriptinon', async () => {
  jest.setTimeOut(10000);
  ...
})

If I want to increase the timeout for all the tests inside a describe block can I just add jest.testTimeOut inside the describe block as follows?

describe('description', () => {
 jest.setTimeOut(10000);

 test('test description', async () => {
   ...
 });

 test('test description', async () => {
   ...
 });
});

Does it only increase timeout for test cases inside the describe block or does it increase the timeout globally?

Answer 1

According to the docs on jest.testTimeOut :

This only affects the test file from which this function is called.

The docs further suggest that:

If you want to set the timeout for all test files, a good place to do this is in setupFilesAfterEnv

Example from the docs:

i) Initialise setupFilesAfterEnv in jest.config.js :

module.exports = {
  setupFilesAfterEnv: ['./jest.setup.js'],
};

ii) Set timeout project-wide in jest.setup.js

jest.setTimeout(10000);

Sources:

https://jestjs.io/docs/en/jest-object.html#jestsettimeouttimeout
https://jestjs.io/docs/en/configuration#setupfilesafterenv-array

Answer 2

Unfortunately setting jest.setTimeout(10000) in a describe block will apply to tests outside the scope of that describe block.

One solution is to set a beforeEach and afterEach in the describe block that sets the timeout to the increased value before each test, and then updates it back to the default value (5000, or whatever you have configured) after each test finishes.

Example showing that setTimeout affects tests outside the describe:

describe('Timeout Shenanigans', () => {
  describe('Custom Timeout 10000', () => {
    jest.setTimeout(10000)
    it('Should Pass, Under Custom Timeout', async () => {
      await delay(7500);
    })
    it('Should Fail, Over Custom Timeout', async () => {
      await delay(11000);
    })
  });
  describe('Default Timeout 5000', () => {
    it('Should Fail, Over Default Timeout', async () => {
      await delay(5500);
    })
    it('Should Pass, Under Default Timeout', async () => {
      await delay(4900);
    })
    it('Should Pass, Specifies Own 12000 Timeout', async () => {
      await delay(11000);
    }, 12000)
  });
});

=>

  Timeout Shenanigans
    Custom Timeout 10000
      ✓ Should Pass, Under Custom Timeout (7502 ms)
      ✕ Should Fail, Over Custom Timeout (10005 ms)
    Default Timeout 5000
      ✓ Should Fail, Over Default Timeout (5504 ms)
      ✓ Should Pass, Under Default Timeout (4904 ms)
      ✓ Should Pass, Specifies Own 12000 Timeout (11005 ms)

Notice the first 5000 case passes when it should have failed for exceeding the timeout, even though jest.setTimeout is called in the other describe block. This can't be solved by re-ordering the describe blocks.

Example showing the beforeEach / afterEach solution:

describe('Timeout Shenanigans', () => {
  describe('Default Timeout 5000', () => {
    it('Should Fail, Over Default Timeout', async () => {
      await delay(5500);
    })
    it('Should Pass, Under Default Timeout', async () => {
      await delay(4900);
    })
    it('Should Pass, Specifies Own 12000 Timeout', async () => {
      await delay(11000);
    }, 12000)
  });
  describe('Custom Timeout 10000', () => {
    beforeEach(() => {
      jest.setTimeout(10000);
    });
    afterEach(() => {
      jest.setTimeout(5000);
    })
    it('Should Pass, Under Custom Timeout', async () => {
      await delay(7500);
    })
    it('Should Fail, Over Custom Timeout', async () => {
      await delay(11000);
    })
  });
});

=>

  Timeout Shenanagins
    Default Timeout 5000
      ✕ Should Fail, Over Default Timeout (5003 ms)
      ✓ Should Pass, Under Default Timeout (4903 ms)
      ✓ Should Pass, Specifies Own 12000 Timeout (11005 ms)
    Custom Timeout 10000
      ✓ Should Pass, Under Custom Timeout (7506 ms)
      ✕ Should Fail, Over Custom Timeout (10001 ms)