Support ESM test files

[novemberborn]

Once avajs/ava#2345 has shipped it should be possible to configure AVA to load ts files as ES modules.

This means we need to import them, instead of using require.

We should also explore if there may be a way to configure this within the typescript configuration.

[cinderblock]

Is this why I'm getting this error?

  C:\Users\Cameron\git\http-terminator\test\http-terminator\http.ts:3
  import createTests from '../helpers/createTests';
  ^^^^^^

  SyntaxError: Cannot use import statement outside a module

  × test\http-terminator\http.ts exited with a non-zero exit code: 1

  Uncaught exception in test\http-terminator\https.ts

[novemberborn]

Yes, right now the files are loaded using require().

[rien]

I am using TypeScript with ES Modules using ts-node. However, when I want to precompile typescript in order speed up the tests, the tests fail with syntax errors:

  Rejected promise returned by test. Reason:

  SyntaxError {
    message: 'Invalid or unexpected token',
  }

  › SyntaxError: Invalid or unexpected token
  › module.exports (node_modules/default-require-extensions/js.js:7:9)

Is there something else I have to do to get this working? I have "module": "commonjs" in my tsconfig.json and I don't have "type": "module" in my package.json.

[novemberborn]

@rien there's not enough context in order for me to help. What is your AVA configuration? TypeScript configuration? This will be better as a new issue.

[rien]

My apologies for hijacking the issue, I thought this could be a straightforward bug. I've tried to make a minimal reproduction, but even with exactly the same stack everything was working fine.

I've been debugging that issue for too long so I've had to switch to jest unfortunately :(

[sindresorhus]

@novemberborn Just so we're on the same page, this issue is about supporting projects that use AVA with @ava/typescript where package.json has "type": "module" and the tsconfig has "module": "es2020", meaning the TS output is native ESM. Correct?

[novemberborn]

@sindresorhus Yes.