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Hello :slightly_smiling_face:

We’re targeting JS and developing a library. We have seen that our jsTest takes 9 min to complete but jvmTest is around 5-6 min. Is there anything we can do to improve performance? We’re using the parallel flag.

Follow-up question: what’s the difference between jsTest and jsNodeTest task?

Thanks
Ola

&gt; jsTest and jsNodeTest task
IIRC `jsTest` automatically "wraps" tests for Node.js or the browser, depending on what you have activated. `jsNodeTest` is the more fine grained task.

&gt; takes 9 min to complete
Given JVM takes 6 minutes, this doesn't look * that * bad.
But you might want to first understand which test(s) is taking longer than what you'd expect.

image.png

Ah thanks for the answer.

We have narrowed down the issue to one module. the modules contains most of our tests (don’t ask shy :slightly_smiling_face: ). They seem to run on one thread.  Or is the console output misleading me? :slightly_smiling_face:

What I really meant is, try to identify the single test cases that take too much time

You can quickly check by running those tests from the IDE

The issue is, I think, that we have many. The ones that takes most time i 1.5s

Ahhh, then I think it might just be the runtime itself that is slow.
I don't recall which version of Mocha K/JS is using, but from v8 parallel mode is supported on Node, so there might be a way to do it

I've looked at the KGP `KotlinMocha` sources, and AFAIU there is no way to specify additional CLI args for Mocha.
Looking at <https://mochajs.org/#parallel-tests> tho, I'm not sure the custom Kotlin `--reporter` supports parallel mode.
<@UAG4QQZB6> might know more about what the K/JS Mocha test runner supports

Mocha can be configured through file, or through `package.json`.
I didn’t test with parallel mode, but in <https://mochajs.org/#reporter-limitations|limitations> I don’t see problems for our reporter
<https://mochajs.org/#configuring-mocha-nodejs>

Looks like the `project.json` way is the quickest way to try it out.

Hm how can I configure it package.json since it’s generated during build time?

Inside your Gradle script, this should do the trick
```compilations.configureEach {
  packageJson {
    customField("mocha", "...")
  }
}```


Moreover, you can do anything you want in `doLast` of `packageJson` task or `testPackageJson`
But for most cases `customField` is enough

Thanks :slightly_smiling_face:

So something like this?
```compilations.configureEach{
    packageJson{
        customField("mocha", "parallel:true")

    }
}```


I think this is what you're looking for
```customField("mocha", mapOf("parallel" to true))```
So that it results in
```"mocha": {
  "parallel": true
}```
Try it out.

Will do :slightly_smiling_face: I’m not that familiar how to work with json in kotlin. However, the output seem correct now :slightly_smiling_face:

Thanks for the help

I managed to decrease the build time from 9 to 6