Mocking a file with a hashbang using the import key fails

[tommy-mitchell]

Given some file cli.js:

#!/usr/bin/env node
import someConstant from "./foo.js";

console.log(someConstant);

Trying to mock this with the import key fails with the error

file:///.../cli.js?esmk=1:1
import {console} from 'file:///import?esmkTreeId=1&esmkModuleId=import&isfound=false&isesm=false&exportNames=console';#!/usr/bin/env node
                                                                                                                      ^

SyntaxError: Invalid or unexpected token
	at ESMLoader.moduleStrategy (node:internal/modules/esm/translators:119:18)
	at ESMLoader.moduleProvider (node:internal/modules/esm/loader:468:14)
	at async link (node:internal/modules/esm/module_job:68:21)

esmock call:

const logs = [];

await esmock("./cli.js", {
	"./foo.js": "bar",
	import: {
		console: { log: (...args) => logs.push(...args) },
	},
});

[tommy-mitchell]

I think the issue is that hashbangs have to be at the start of the file (MDN):

A hashbang comment ... is only valid at the absolute start of a script or module. Note also that no whitespace of any kind is permitted before the #!. The comment consists of all the characters after #! up to the end of the first line; only one such comment is permitted.

esmock is inserting import globals before the hashbang.

[koshic]

Very similar issue without hashbang.

foo.js

export default 1;

cli.js

import someConstant from "./foo.js";

console.log(someConstant);

1.js

import esmock from "esmock";

await esmock("./cli.js", {
  "./foo.js": "bar",
});

file:///Users/xxxfoo.js?esmkTreeId=1&esmkModuleId=./foo.js&isfound=true&isesm=false&exportNames=0,1,2,default:1
export const 0 = global.esmockCacheGet("file:///Users/xxx/foo.js?esmkTreeId=1&esmkModuleId=./foo.js&isfound=true&isesm=false&exportNames=0,1,2,default").0
             ^

SyntaxError: Unexpected number
    at CustomizedModuleLoader.moduleStrategy (node:internal/modules/esm/translators:116:18)
    at CustomizedModuleLoader.moduleProvider (node:internal/modules/esm/loader:190:14)

[iambumblehead]

esmock is inserting import globals before the hashbang.

I think you are correct :) thanks for finding this. I should have time this evening or tomorrow to look at PRs or try to resolve it myself

[iambumblehead]

I don't know why the win32 error is occurring. The error indicates that paths like "node:fs" are only available in esm to packages using "type": "module", but the error originates inside an esm "load" hook and tests are started inside the tests-source-map folder which includes a package.json with "type": "module"

I don't know what causes the issue

[iambumblehead]

related nodejs/node#35518

[iambumblehead]

The ci error went away when node 18.16 was pinned. The error occurs on the latest 18.17

A new ticket is created at the node repo here let's see what they say nodejs/node#48948

[iambumblehead]

closing with this #217

feel free to reopen for any reason