Improve new test

Author: GeoffreyBooth

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

@@ -411,11 +411,16 @@ describe('--experimental-detect-module', { concurrency: !process.env.TEST_PARALL
           'import { pathToFileURL } from "node:url";' +
           'register("./transpile-esm-to-cjs.mjs", pathToFileURL("./"));'
         )}`,
-        fixtures.path('es-modules/package-without-type/esm-with-check.js'),
+        fixtures.path('es-modules/package-without-type/module.js'),
       ], { cwd: fixtures.fileURL('es-module-loaders/') });
 
       strictEqual(stderr, '');
-      strictEqual(stdout, 'module\ncommonjs\ntransformed!\n');
+      strictEqual(stdout, `
+        Resolved format: module
+        Loaded original format: module
+        executed
+        Evaluated format: commonjs
+        `.replace(/^\s+/gm, ''));
       strictEqual(code, 0);
       strictEqual(signal, null);
     });

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

@@ -3,20 +3,22 @@ import { writeSync } from "node:fs";
 export async function resolve(specifier, context, next) {
   const result = await next(specifier, context);
   if (specifier.startsWith("file://")) {
-    writeSync(1, result.format + '\n');
+    writeSync(1, `Resolved format: ${result.format}\n`);
   }
   return result;
 }
 
 export async function load(url, context, next) {
   const output = await next(url, context);
+  writeSync(1, `Loaded original format: ${output.format}\n`);
+
   let source = `${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);')
+  // This is a very incomplete and naively done implementation for testing purposes only
+  if (source?.includes('export default')) {
+    source = source.replace('export default', 'module.exports =');
 
-    source += '\nconsole.log("transformed!");'; // To verify the hook ran
+    source += '\nconsole.log(`Evaluated format: ${this === undefined ? "module" : "commonjs"}`);';
 
     output.source = source;
     output.format = 'commonjs';