chore(test): validate that requiring TS from ESM works

README.md

@@ -45,7 +45,8 @@ require('./myFile.ts'); // works
 ### Limitations
 
 - You can't import `.ts` files from ESM. If you want to use ESM syntax, you have
-  convert the file to TS and use `.ts` file extension.
+  convert the file to TS and use `.ts` file extension, or use
+  [`createRequire`](https://nodejs.org/api/module.html#modulecreaterequirefilename).
 - By default, we only support `.js` and `.ts` file extensions.
 - Windows would only support the `node -r @transloadit/ts-fly …` form, as the
   executable is a POSIX shell script.

test/esmEntryPoint.test.mjs

@@ -0,0 +1,80 @@
+import { Buffer } from 'node:buffer';
+import { fileURLToPath } from 'node:url';
+import { join } from 'node:path';
+import { once } from 'node:events';
+import { spawn } from 'node:child_process';
+import { platform, tmpdir } from 'node:os';
+import assert from 'node:assert';
+import fs from 'node:fs/promises';
+
+const ROOT_DIR = new URL('../', import.meta.url);
+const { bin } = JSON.parse(
+	await fs.readFile(new URL('./package.json', ROOT_DIR), 'utf-8'),
+);
+
+const tmpDir = await fs.mkdtemp(join(tmpdir(), 'tsen-test-'));
+
+await Promise.all([
+	fs.writeFile(
+		join(tmpDir, 'entryPoint.mjs'),
+		`#!${
+			// macOS doesn't support shebangs pointing at scripts for some reason
+			(platform() === 'darwin' ? '/usr/bin/env ' : '') +
+			fileURLToPath(new URL(bin, ROOT_DIR))
+		}\n
+    'use strict';
+    import {createRequire} from 'node:module';
+    const require = createRequire(import.meta.url);
+    await 'top-level';
+    console.log('require', require('./require.ts'));
+    import('./dynamic.ts').then(module => console.log('dynamic TS', Object.keys(module)), console.error);
+    import('./dynamic.mjs').then(module => console.log('dynamic ESM', Object.keys(module)), console.error);
+    \n`,
+		'ascii',
+	),
+
+	fs.writeFile(join(tmpDir, 'require.ts'), 'export const a = 1'),
+	fs.writeFile(join(tmpDir, 'reexported.js'), 'exports.c = 1'),
+
+	fs.writeFile(
+		join(tmpDir, 'dynamic.ts'),
+		`"use strict";
+    export default 1;
+    export const a = 1;
+    export const b = 1;
+    export * from "./reexported.js";
+    \n`,
+	),
+
+	fs.writeFile(
+		join(tmpDir, 'dynamic.mjs'),
+		`
+    export default 1;
+    export const a = 1;
+    export const b = 1;
+    export * from "./reexported.js";
+    \n`,
+	),
+]);
+
+await Promise.all([fs.chmod(join(tmpDir, 'entryPoint.mjs'), 0o777)]);
+
+try {
+	const cp = spawn(join(tmpDir, 'entryPoint.mjs'));
+
+	const [exitStatus, stdoutArray, stderrArray] = await Promise.all([
+		once(cp, 'exit'),
+		cp.stdout.toArray(),
+		cp.stderr.toArray(),
+	]);
+
+	const stdout = Buffer.concat(stdoutArray).toString('utf-8');
+	const stderr = Buffer.concat(stderrArray).toString('utf-8');
+
+	assert.match(stdout, /^require \{ a: 1 \}$/m);
+	assert.match(stderr, /Unknown file extension ".ts"/);
+	assert.match(stdout, /^dynamic ESM \[ 'a', 'b', 'c', 'default' \]$/m);
+	assert.deepStrictEqual(exitStatus, [0, null]);
+} finally {
+	await fs.rm(tmpDir, { recursive: true, force: true });
+}