Test ES modules don't seem to work without esm package

[mightyiam]

Thank you for my favorite test runner.

The ES modules recipe says:

By default AVA converts ES module syntax to CommonJS. You can disable this.

The Babel recipe also says:

By default our Babel pipeline is applied to test and helper files ending in .js.

And it also says:

By default AVA's stage-4 preset will convert ES module syntax to CommonJS. This can be disabled.

But my tests, which are written in TypeScript and ES modules and are not transpiled to CommonJS, but remain ES modules, are failing AVA. Here is a copy paste from my terminal:

➜  pick-path-router git:(ava-no-esm) head lib/index.test.js
import test from 'ava';
import xs from 'xstream';
import { div } from '@cycle/dom';
import Subject from '.';
import { mockTimeSource } from '@cycle/time';
const testPageSinks = {
    title: xs.of('foo'),
    breadcrumbs: xs.of([]),
    DOM: xs.of(div())
};
➜  pick-path-router git:(ava-no-esm) npx ava    


  ✖ No tests found in lib/index.test.js

  1 uncaught exception

  Uncaught exception in lib/index.test.js

  /home/mightyiam/src/cycle-components/pick-path-router/lib/index.test.ts:4

  /home/mightyiam/src/cycle-components/pick-path-router/lib/index.js:1
  import xs from 'xstream';
  ^^^^^^

  SyntaxError: Cannot use import statement outside a module

Here is the pull request where I am trying to remove usage of the esm package:
https://github.com/cycle-components/pick-path-router/pull/93

Here are the changes.

And here is the failure in the CI log.

[mightyiam]

Sorry. Somehow submitted prematurely. Editing.

[mightyiam]

Done editing description.

[novemberborn]

AVA only transpiles your test files though. This error is coming from a source file.

The good news, as it were, is that we're looking to remove the out-of-the-box transpilation. So at least things will be less confusing.

(I'm closing this issue for housekeeping purposes, but let's keep the conversation going.)

[mightyiam]

Thank you for the information, @novemberborn.

So it seems that I'm doing the right thing using the esm package.