Mock
Datewhen run unit test cases with jest. Make tests ofDateeasier.
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canvaswhen run unit test cases with jest.
This should only be installed as a development dependency (devDependencies) as it is only designed for testing.
npm i --save-dev jest-date-mockIn your package.json under the jest, create a setupFiles array and add jest-date-mock to the array.
{
"jest": {
"setupFiles": ["jest-date-mock"]
}
}If you already have a setupFiles attribute you can also append jest-date-mock to the array.
{
"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
import 'jest-date-mock';
// or
require('jest-date-mock');Add that file to your setupFiles array:
"jest": {
"setupFiles": [
"./__setups__/date.js"
]
}Use the only
3 apifor test cases.
advanceBy(ms): advance date timestamp byms.advanceTo([timestamp]): reset date totimestamp, default to0.clear(): shut down the mock system.
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.
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.
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