Issue with jest environment

[r4ul90]

I have a test case, that runs using jsdom (@jest-environment jsdom) because it requires some window operations. One of the components involved in this test case, recently received telemetry support via the opentelemetry library. However the test case is throwing a TypeError: timer.unref is not a function error. I looked at the file that is throwing the error (timer-util.js), there are two implementations, the file from the node folder is being executed instead of the folder from the browser file. Am I missing some configuration maybe?

[Flarna]

Supported runtimes are browsers and node.js (see here for more details). Other runtimes like deno,... or toolings which modify a runtime to look like another may work but there is no guarantee nor tests.

If I understand jest-environment-jsdom correct it uses node.js as runtime to simulate a browser. Maybe the simulation is incomplete which results in wrong variant of opentelemetry is used. Or the runtime detection of OTel is not good enough.

Not sure if the runtime detection can be easily extended to detect jest-environment-jsdom as browser. Besides that I'm also not sure if the browser emulation of jest-environment-jsdom goes that far that everything (e.g. exporters,...) works like in a browser.

Maybe @SimenB has some hints how to close this gap.

[SimenB]

Hello! Without digging too deep, I'm guessing this is because OTel uses browser property in package.json rather than browser condition within exports.

opentelemetry-js/packages/opentelemetry-core/package.json

Lines 8 to 13 in 9328558

	"browser": {
	"./src/platform/index.ts": "./src/platform/browser/index.ts",
	"./build/esm/platform/index.js": "./build/esm/platform/browser/index.js",
	"./build/esnext/platform/index.js": "./build/esnext/platform/browser/index.js",
	"./build/src/platform/index.js": "./build/src/platform/browser/index.js"
	},

This is unsupported out of the box, but our docs provide an example of how to configure the resovler.

https://jestjs.io/docs/configuration#resolver-string

That said, would be nice if OTel used exports stanza with browser condition.

[r4ul90]

@SimenB thanks for your reply. @Flarna would you consider a change for including the browser condition within exports as @SimenB has suggested?

[m10241]

@SimenB
Thanks for the input!
Our app has tests that need to be run in node env, and there are some that need to run in browser env.

I tried the link you sent and it works perfectly for the test files that have docblock at the top like this (browser env):

/**
 * @jest-environment jsdom
 */

But when it comes to the test files that actually need node env, they will fail and start complaining about window is not defined.
I have tried adding some more logic to the resolver, tried packageFilter and pathFilter, but got no luck.
So, would you please share your thoughts on how to tackle this issue?

[m10241]

I also was able to confirm that jest is processing the package.json file, which has browser instructions in it. But for some reason, it is not able to pick the right timer-util from browser folder, instead of node folder.

[myaaia]

@SimenB do you have any resolution on this? we are stuck with the resolver, can you advise how to have a resolver that will support both node and browser for a given app?

[fragsalat]

I got the issue as well. Jest + JSDom trying to test some tracing functionality. Calling span's end function I'm getting as well the issue about the unref function.

[m10241]

So far, I have found two ways of resolving it:

1. Mock entire otel lib in your tests (because you really don't need to report signals during tests)
2. Write a custom resolver and point to it in your jest.config

Here is a sample code that worked for me!

// resolver.js
module.exports = function (file, options) {
  // defaulting it to the default resolver
  const resolver = require("resolve");
  // run the resolver normally to find the full file path
  let filepath = resolver.sync(file, {
    basedir: options.basedir,
    extensions: options.extensions,
    moduleDirectory: options.moduleDirectory,
    paths: options.paths,
  });
  // add a check to make sure we replace the file when we should
  if (
    filepath.indexOf(
      "@opentelemetry/core/build/src/platform/node/timer-util.js"
    ) > -1
  ) {
    filepath = filepath.replace("/node/", "/browser/");
  }
  return filepath;
};

And in your jest.config.ts you can do this

module.exports = {
  resolver: // path_to_your_resolver.js
}

[fragsalat]

The first option I would not really consider as viable as the repo where I face the issue is actually a wrapper library for our company to make the ot lib more usable and fill some defaults. So we are expecting things to be reported normally and we catch them at the exporter level.
The 2nd option sounds viable but quite ugly