Cook

Catch error

• source: https://stackoverflow.com/questions/46042613/how-to-test-type-of-thrown-exception-in-jest

test("Test description", () => {
  const t = () => {
    throw new TypeError();
  };
  expect(t).toThrow(TypeError);
});

async

• source: https://jestjs.io/docs/en/tutorial-async#error-handling

// Testing for async errors using Promise.catch.
it('tests error with promises', () => {
  expect.assertions(1);
  return user.getUserName(2).catch(e =>
    expect(e).toEqual({
      error: 'User with 2 not found.',
    }),
  );
});

// Or using async/await.
it('tests error with async/await', async () => {
  expect.assertions(1);
  try {
    await user.getUserName(1);
  } catch (e) {
    expect(e).toEqual({
      error: 'User with 1 not found.',
    });
  }
});

Add Delay to Watch

• not implemented, see https://github.com/facebook/jest/issues/4234