# jsBrowserTest for a multiplatform library

**URL:** <https://discuss.kotlinlang.org/t/jsbrowsertest-for-a-multiplatform-library/19422>\
**Category:** Multiplatform\
**Created:** [October 8, 2020, 12:35pm UTC](https://discuss.kotlinlang.org/t/jsbrowsertest-for-a-multiplatform-library/19422 "2020-10-08T12:35:01Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![claude.brisson](https://avatars.discourse-cdn.com/v4/letter/c/a3d4f5/32.png) [@claude.brisson](https://discuss.kotlinlang.org/u/claude.brisson)\
**Post date:** [October 8, 2020, 12:35pm UTC](https://discuss.kotlinlang.org/t/jsbrowsertest-for-a-multiplatform-library/19422/1 "2020-10-08T12:35:01Z")

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I have a 1.4.10 multiplatform library, targeting for now js(LEGACY) and jvm, with a rather standard build script using the kotlin DSL. Since it’s a library, I don’t have any `main()` function.

I have some questions about the `jsBrowserTest` task:

1. Where is it originally defined? Grepping the whole kotlin and gradle sources didn’t help. I saw some references to metacity in the gradle debug logs.
2. I understand it is launching a (potentially headless) browser, chosen in the js karma (I’ve read somewhere that it’s best to use a chrome family browser for js maps to properly work). But on which address? If I were to inspect the http traffic with a tool like wireshark or tcpdump, which localhost port should I watch?
3. If I have a resource located in `src/commonTest/resources`, it’s visible in the classpath for the `jvmTest` task ; but how to get hold of it for the `jsBrowserTest`? I guess it would involve some ajax call, but towards which URI? Does it involve something like a tests webpack or so?
4. Is remote debugging supposed to work with latest versions of Intellij Idea? Using chromium, the debugger seems to hang when running `jsBrowserTest`. Can it be so because on my ubuntu, chromium is installed by snap?

Thanks.

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<div class="post-metadata">

**Author:** ![claude.brisson](https://avatars.discourse-cdn.com/v4/letter/c/a3d4f5/32.png) [@claude.brisson](https://discuss.kotlinlang.org/u/claude.brisson)\
**Post date:** [October 20, 2020, 3:43pm UTC](https://discuss.kotlinlang.org/t/jsbrowsertest-for-a-multiplatform-library/19422/2 "2020-10-20T15:43:04Z")

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Kinda responding to myself.

1. The jsBrowserTask is defined in the kotlin multiplatform plugin.

2. It runs a nodejs HTTP server on the port 9876. The browser is opened on an URL like `GET /?id=34002427`, which then loads `/socket.io/socket.io.js`, then `/absolute/path/to/project/build/js/node_modules/mocha/mocha.js?...`, then `/context..html`, `/context.js`, some other mocha resources, and then everything happens within websocket connections. On the server side, I see several references in the log: metacity, several npm packages, …

3. I guess there is a way of having some kind of expect/actual getResource function, that would hit the classpath under the jvm, and use the ktor client -for instance- to fetch the resource using an /absolute/ URL (parametrized or deduced in some way…). Right now, I just turn on an external basic HTTP server on my `build/processedResources/js/test/` directory.

4. I don’t know yet about this one. But it seems like js tooling has a foot in the jvm island and another one in the nodejs one. I’m pretty sure there would be a way to make everyone happy, by having a pure jvm tooling on the server for browser tests.