Testing AssemblyScript function with Jest results in error "TextDecoder is not defined"

[Odisseuss]

Hello. I am not really sure if this is the right place to ask this question, but here I go.

I am trying to test an AssemblyScript function, but when running my Jest tests, I get the following error which seems to have something to do with the AssemblyScript loader.

Did anyone manage to test his/her code with Jest?

Thanks

[dcodeIO]

What's your node.js version?

[Odisseuss]

@dcodeIO I am working with node 12.18

[dcodeIO]

Hmm, according to the node.js docs, TextDecoder was added as a global in v11.0.0. May be a problem with Jest not exposing it then.

[dcodeIO]

Found this thread with a potential solution at the end: jestjs/jest#10523

[Odisseuss]

Hm, it seems that after following the steps in the thread, the error message changed:

[MaxGraey]

I recommend update node.js at least to 13.x (but better to latest version ofc)

[dcodeIO]

The error seems to indicate that Jest refuses to load the loader as an ES module. The first bullet point appears to offer a solution, or you can try import { ... } from "@assemblyscript/loader/umd";.

[Odisseuss]

Updating node.js to version 14 and changing the assemblyscript loader import from
import { instantiateStreaming } from "@assemblyscript/loader"; to import { instantiateStreaming } from "@assemblyscript/loader"; fixed that issue.

Now it seems that i cannot load the .wasm files because jest-fetch-mock does not support relative URLs. I am using fetch in a component that loads the AssemblyScript module as follows:

import { instantiateStreaming } from "@assemblyscript/loader";
import ModuleTypes from "../asTypes";

export const loadWasm = instantiateStreaming<typeof ModuleTypes>(
  fetch("optimized.wasm")
).then(({ exports }) =>
  Object.assign({}, exports, {
    YinDetector: (
      arrayValues: Float32Array,
      threshold: number,
      sampleRate: number,
      probabilityThreshold: number
    ) => {
      const pInput = exports.__retain(
        exports.__newArray(exports.Float32AudioBuffer_ID, arrayValues)
      );
      const pOutput = exports.YIN(
        pInput,
        threshold,
        sampleRate,
        probabilityThreshold
      );
      exports.__release(pInput);
      return pOutput;
    },
  })
);

I am getting this following error:

[MaxGraey]

Btw did you know we have nice jest compatible testing library written on AS for AS which works should works without any problems and don't even require loader and passing data from and back to host?
https://github.com/jtenner/as-pect

[MaxGraey]

Regarding your jest error. It seems node-fetch can't resolve relative path somehow. Try to use absolute path for your optimized.wasm

[Odisseuss]

@MaxGraey

Btw did you know we have nice jest compatible testing library written on AS for AS which works should works without any problems and don't even require loader and passing data from and back to host?
https://github.com/jtenner/as-pect

Yes, I stumbled upon as-pect on some threads regarding AS testing. I wanted to use Jest for writing some tests that compare two algorithms in terms of speed and accuracy. But I dropped that and wrote the comparison tests in pain TSX.

Thanks a lot for all the support. This issue can be closed now

[mrchantey]

Adding this to my jest.config solved it for me

module.exports = {
	testEnvironment: 'node'
}