add test that detection doesn't interfere with hooks

test/es-module/test-esm-detect-ambiguous.mjs

@@ -400,6 +400,25 @@ describe('--experimental-detect-module', { concurrency: !process.env.TEST_PARALL
       strictEqual(code, 0);
       strictEqual(signal, null);
     });
+
+    it('should detect the syntax of the source as returned by a custom load hook', async () => {
+      const { code, signal, stdout, stderr } = await spawnPromisified(process.execPath, [
+        '--no-warnings',
+        '--experimental-detect-module',
+        '--import',
+        `data:text/javascript,${encodeURIComponent(
+          'import { register } from "node:module";' +
+          'import { pathToFileURL } from "node:url";' +
+          'register("./transpile-esm-to-cjs.mjs", pathToFileURL("./"));'
+        )}`,
+        fixtures.path('es-modules/package-without-type/esm-with-check.js'),
+      ], { cwd: fixtures.fileURL('es-module-loaders/') });
+
+      strictEqual(stderr, '');
+      strictEqual(stdout, 'commonjs\ntransformed!\n');
+      strictEqual(code, 0);
+      strictEqual(signal, null);
+    });
   });
 });
 

test/fixtures/es-module-loaders/transpile-esm-to-cjs.mjs

@@ -0,0 +1,16 @@
+export async function load(url, context, next) {
+  const output = await next(url, context);
+  let source = `${output.source}`
+
+  // This is a very naive implementation for testing purposes only
+  if (source?.includes('import')) {
+    source = source.replace(/import\s+{\s*([^;]+)\s*}\s+from\s+(['"])(.*?)\2;/g, 'const { $1 } = require($2$3$2);')
+
+    source += '\nconsole.log("transformed!");'; // To verify the hook ran
+
+    output.source = source;
+    output.format = 'commonjs';
+  }
+
+  return output;
+}

test/fixtures/es-modules/package-without-type/esm-with-check.js

@@ -0,0 +1,2 @@
+import { version } from 'node:process';
+console.log(this === undefined ? 'module' : 'commonjs');