Jest: runTimersToTime does not execute a function that is debounced using lodash's debounce.

[cameron-martin]

Do you want to request a _feature_ or report a _bug_?

Bug

What is the current behavior?

Advancing jest timers does not call a function which is debounced using lodash's debounce function.

If the current behavior is a bug, please provide the steps to reproduce and
either a repl.it demo through https://repl.it/languages/jest or a minimal
repository on GitHub that we can yarn install and yarn test.

Execute the following test, and it should pass but at the moment it does not.

var debounce = require('lodash/debounce');

jest.useFakeTimers();

test('foo', function() {
    const mock = jest.fn();

    const fn = debounce(mock, 1000);
    fn();

    jest.runTimersToTime(1200);

    expect(mock).toHaveBeenCalledTimes(1);
});

https://repl.it/repls/BlushingGrayGharial

What is the expected behavior?

The debounced function should be called.

Please provide your exact Jest configuration and mention your Jest, node,
yarn/npm version and operating system.

Jest configuration

  {
    "moduleFileExtensions": [
      "ts",
      "tsx",
      "js"
    ],
    "transform": {
      "^.+\\.(ts|tsx)$": "babel-jest"
    },
    "testMatch": [
      "**/__tests__/*.(ts|tsx|js)"
    ],
    "setupFiles": [
      "<rootDir>/jestEnvironment.js"
    ]
  }

Versions

• npm - 5.3.0
• node - v8.6.0
• jest - v22.0.3
• OS - Windows 10

[cpojer]

You have to enable fake timers before requiring lodash or using setTimeout, otherwise fake timers will not be used.

[cameron-martin]

This still does not work, see the updated repl:

https://repl.it/repls/BlushingGrayGharial

[SimenB]

I can confirm it doesn't work, might be better tracked in #3465, though

[thymikee]

Yup this is a dupe. It won’t work because lodash doesn’t use timers to schedule denounce and throttle

[cameron-martin]

Interestingly, using sinon's fake timers to do the same thing works.