fix: ignore virtual modules from other plugins

src/index.js

@@ -71,12 +71,17 @@ export default function commonjs ( options = {} ) {
 	let entryModuleIdsPromise = null;
 
 	function resolveId ( importee, importer ) {
-		if ( importee === HELPERS_ID ) return importee;
-
-		if ( importer && startsWith( importer, PREFIX ) ) importer = importer.slice( PREFIX.length );
-
 		const isProxyModule = startsWith( importee, PREFIX );
-		if ( isProxyModule ) importee = importee.slice( PREFIX.length );
+		if ( isProxyModule ) {
+			importee = importee.slice( PREFIX.length );
+		}
+		else if ( startsWith( importee, '\0' ) ) {
+			return importee;
+		}
+
+		if ( importer && startsWith( importer, PREFIX ) ) {
+			importer = importer.slice( PREFIX.length );
+		}
 
 		return resolveUsingOtherResolvers( importee, importer ).then( resolved => {
 			if ( resolved ) return isProxyModule ? PREFIX + resolved : resolved;

test/samples/ignore-virtual-modules/main.js

@@ -0,0 +1 @@
+module.exports = require('\0virtual');

test/test.js

@@ -576,5 +576,19 @@ describe( 'rollup-plugin-commonjs', () => {
 				assert.equal( error.frame, '1: export const foo = 2,\n                        ^' );
 			}
 		});
+
+		it('ignores virtual modules', async () => {
+			const bundle = await rollup({
+				input: 'samples/ignore-virtual-modules/main.js',
+				plugins: [ commonjs(), {
+					load (id) {
+						if (id === '\0virtual') {
+							return 'export default "Virtual export"';
+						}
+					}
+				} ]
+			});
+			assert.equal( (await executeBundle( bundle )).exports, 'Virtual export' );
+		});
 	});
 });