Mock `window.Date` when run unit test cases with jest. Make tests of `Date` easier.
npm install jest-date-mock> Mock Date when run unit test cases with jest. Make tests of Date easier.
> - jest-random-mock Mock Math.random in jest, with deterministic random generator.
> - jest-canvas-mock Mock canvas when run unit test cases with jest.
This should only be installed as a development dependency (devDependencies) as it is only designed for testing.
``bash`
npm i --save-dev jest-date-mock
In your package.json under the jest, create a setupFiles array and add jest-date-mock to the array.
`js`
{
"jest": {
"setupFiles": ["jest-date-mock"]
}
}
If you already have a setupFiles attribute you can also append jest-date-mock to the array.
`js`
{
"jest": {
"setupFiles": ["./__setups__/other.js", "jest-date-mock"]
}
}
More about in configuration section.
Alternatively you can create a new setup file which then requires this module or
add the require statement to an existing setup file.
__setups__/date.js
`js`
import 'jest-date-mock';
// or
require('jest-date-mock');
Add that file to your setupFiles array:
`js`
"jest": {
"setupFiles": [
"./__setups__/date.js"
]
}
> Use the only 3 api for test cases.
- advanceBy(ms): advance date timestamp by ms.advanceTo([timestamp])
- : reset date to timestamp, default to 0.clear()
- : shut down the mock system.
`js
import { advanceBy, advanceTo, clear } from 'jest-date-mock';
test('usage', () => {
advanceTo(new Date(2018, 5, 27, 0, 0, 0)); // reset to date time.
const now = Date.now();
advanceBy(3000); // advance time 3 seconds
expect(+new Date() - now).toBe(3000);
advanceBy(-1000); // advance time -1 second
expect(+new Date() - now).toBe(2000);
clear();
Date.now(); // will got current timestamp
});
`
More sample code here.
Also, add an API Date.current() to get the actual current timestamp.
`js
import { advanceBy, advanceTo, clear } from 'jest-date-mock';
advanceTo(0); // reset to timestamp = 0
Date.now(); // will got 0
Date.current(); // will got the actual timestamp.
``
MIT@hustcc.