Jest: How to send node command line arguments in jest test

[Pasupathi-Rajamanickam]

I have a utility.js which uses program arguments through process.argv.

When I run jest -t 'utility-spec' --arg1 value1 --arg2 value2 it's throwing exception. Failed to run the test.

(node:8956) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): ● Unrecognized CLI Parameters:

Following options were not recognized: ["arg1", "arg2"]

How to pass my program argument.?

[cpojer]

Jest doesn't accept node arguments unfortunately. I recommend testing your utility by making a programmatic interface. You can also overwrite process.argv in your test before requiring your module.

[rambabusaravanan]

@cpojer Can you please show us a sample how to do that?

[SimenB]

https://repl.it/@SimenB/SphericalFirsthandOpengroup

[Pasupathi-Rajamanickam]

@rambabusaravanan
I did this in my spec.js at the top

process.argv.push('--arg1', 'value1');

describe('check', () => {
.....
});

[GuiF007]

This should not be blocking at all... My Jenkins jobs crash because of that errors, with proxy configuration...

[roryokane]

For convenience, and in case Repl.it disappears in the future, here is the code that @SimenB linked to in their comment:

test.js

~~~js
process.argv = ['node', 'jest', '--arg1', '1', '--arg2', 'hello']

const argv = require('./argv');

test('argv', () => {
expect(argv).toEqual(['--arg1', '1', '--arg2', 'hello']);
});
~~~

argv.js

~js
module.exports = process.argv.slice(2);
~

[tomnlittle]

It's worth noting that this also works if you put it in a jest setup file

Jest configuration - jest.config.js

module.exports = {
    setupFiles: ['./setup'],
};

Setup File - setup.js

process.argv = ['node', 'jest', 'arg1', 'arg2'];

[akopchinskiy]

process.argv.push('--config');  // your flag
process.argv.push('config-local.json');  // flag value

[bendulum]

This information might be useful to someone:

I have an npm task which I run via npm run jest -- --password=MY_PASSWORD.
The npm task: "jest": "jest --passWithNoTests --forceExit --silent"

There is a single test file:

test('database', () => {
    return new Promise(function(resolve, reject) {
        dbConnect(function(err, db) {
            if (err) return reject(err);
            resolve(db);
        });
    });
});

dbConnect internally reads password from process.argv to connect to the database. This works, the argument that I pass when running npm is available in dbConnect. However, as soon as there are two test files it no longer works because then the arguments get swallowed.

A very bad workaround is running with --maxWorkers=1. With --maxWorkers=2 the second item in process.argv is node_modules/jest-worker/build/workers/processChild.js, otherwise it's node_modules/.bin/jest. I think if there is only one test file it will also use node_modules/.bin/jest, so the arguments are passed down.

I was surprised when my tests broke after "not changing anything", not realizing what I did was adding a second test file, which then broke everything. But I didn't see it mentioned anywhere that maxWorkers has that effect.

I've tried other methods of injecting my custom --password=MY_PASSWORD argument so it's available in test files but it only works with --maxWorkers=1 or when using only a single test file. :woman_shrugging:

• node 14.15.0
• npm 6.14.8
• jest 25.5.4
• jest-extended 0.11.5
• babel-jest 25.5.1
• babel-plugin-require-context-hook 1.0.0

Setup file:

require('babel-plugin-require-context-hook/register')();
require('regenerator-runtime/runtime');