Demonstrates differences between loader-returned sources; between import examplejs from './example.js' and import examplejson from './example.json' assert { type: 'json' }

With node v20.6+, use npm test,

import test from 'node:test'
import assert from 'node:assert'
import module from 'node:module'

module.register('./loader.js', {
  parentURL: import.meta.url
})

// _importing.js_
// ```
// import JSobj from './example.js'
// import JSONobj from './example.json' assert { type: 'json' }
// 
// export { JSobj, JSONobj }
// ```

// for "module" type modules, the loader can return different versions
// of that "module" source to multiple import contexts (desired behaviour),
test('loader can return fresh source, js', async () => {
  const importOne = await import('./importing.js?t=1')
  const importTwo = await import('./importing.js?t=2')

  assert.deepEqual(importOne.JSobj, { example: 'js-1' })
  assert.deepEqual(importTwo.JSobj, { example: 'js-2' })
})

// for "json" type modules, the loader cannot return different versions
// of that "json" source to different import contexts and, instead, the
// first version is seemingly cache-returned to any subsequently-importing 
// context (not-desired behaviour)
test('loader cannot return fresh source, json', async () => {
  const importThree = await import('./importing.js?t=3')
  const importFour = await import('./importing.js?t=4')

  assert.deepEqual(importThree.JSONobj, { example: 'json-3' })
  assert.deepEqual(importFour.JSONobj, { example: 'json-4' })
  // ^^ fails: importFour.JSONobj == `{ example: 'json-3' }`
})