module: reintroduce package exports dot main

This reintroduces the dot main in exports as discussed in the previous
Node.js modules meeting.

The implementation includes both CommonJS and ES module resolution with
the associated documentation and resolver specification changes.

In addition to the dot main, "exports" as a string or direct fallback
array is supported as well.

Co-Authored-By: Geoffrey Booth <GeoffreyBooth@users.noreply.github.com>
PR-URL: https://github.com/nodejs/node/pull/29494
Reviewed-By: Jan Krems <jan.krems@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>

1 files changed, 2 insertions, 12 deletions

diff --git a/test/es-module/test-esm-exports.mjs b/test/es-module/test-esm-exports.mjs
index 4f77252158..5059a2d418 100644
--- a/test/es-module/test-esm-exports.mjs
+++ b/test/es-module/test-esm-exports.mjs
@@ -20,6 +20,8 @@ import { requireFixture, importFixture } from '../fixtures/pkgexports.mjs';
     // Fallbacks
     ['pkgexports/fallbackdir/asdf.js', { default: 'asdf' }],
     ['pkgexports/fallbackfile', { default: 'asdf' }],
+    // Dot main
+    ['pkgexports', { default: 'asdf' }],
   ]);
   for (const [validSpecifier, expected] of validSpecifiers) {
     if (validSpecifier === null) continue;
@@ -81,18 +83,6 @@ import { requireFixture, importFixture } from '../fixtures/pkgexports.mjs';
     }));
   }
 
-  // There's no main field so we won't find anything when importing the name.
-  // The fact that "." is mapped is ignored, it's not a valid main config.
-  loadFixture('pkgexports').catch(mustCall((err) => {
-    if (isRequire) {
-      strictEqual(err.code, 'MODULE_NOT_FOUND');
-      assertStartsWith(err.message, 'Cannot find module \'pkgexports\'');
-    } else {
-      strictEqual(err.code, 'ERR_MODULE_NOT_FOUND');
-      assertStartsWith(err.message, 'Cannot find main entry point');
-    }
-  }));
-
   // Covering out bases - not a file is still not a file after dir mapping.
   loadFixture('pkgexports/sub/not-a-file.js').catch(mustCall((err) => {
     strictEqual(err.code, (isRequire ? '' : 'ERR_') + 'MODULE_NOT_FOUND');