Support resolve 1.11.1, add built-in test (#223)

src/index.js

@@ -234,10 +234,29 @@ export default function nodeResolve ( options = {} ) {
 				resolveOptions.preserveSymlinks = preserveSymlinks;
 			}
 
+			const importeeIsBuiltin = builtins.has(importee);
+			const forceLocalLookup = importeeIsBuiltin && (!preferBuiltins || !isPreferBuiltinsSet);
+			let importSpecifier = importee;
+
+			if (forceLocalLookup) {
+				// need to attempt to look up a local module
+				importSpecifier += '/';
+			}
+
 			return resolveIdAsync(
-				importee,
+				importSpecifier,
 				Object.assign( resolveOptions, customResolveOptions )
 			)
+				.catch(err => {
+					if (forceLocalLookup && err.code === 'MODULE_NOT_FOUND') {
+						// didn't find a local module, so fall back to the importee
+						// (i.e. the builtin's name)
+						return importee;
+					}
+
+					// some other error, just forward it
+					throw err;
+				})
 				.then(resolved => {
 					if ( resolved && packageBrowserField ) {
 						if ( packageBrowserField.hasOwnProperty(resolved) ) {
@@ -255,9 +274,9 @@ export default function nodeResolve ( options = {} ) {
 							resolved = fs.realpathSync( resolved );
 						}
 
-						if ( builtins.has( resolved ) ) {
+						if (builtins.has(resolved) && preferBuiltins && isPreferBuiltinsSet) {
 							return null;
-						} else if ( builtins.has( importee ) && preferBuiltins ) {
+						} else if (importeeIsBuiltin && preferBuiltins) {
 							if ( !isPreferBuiltinsSet ) {
 								this.warn(
 									`preferring built-in module '${importee}' over local alternative ` +

test/test.js

@@ -29,11 +29,11 @@ function executeBundle ( bundle ) {
 	return bundle.generate({
 		format: 'cjs'
 	}).then( generated => {
-		const fn = new Function ( 'module', 'exports', 'assert', generated.output[0].code );
+		const fn = new Function ( 'module', 'exports', 'assert', 'require', generated.output[0].code );
 		const module = { exports: {} };
 
 		try {
-			fn(module, module.exports, assert);
+			fn(module, module.exports, assert, require);
 		} catch (error) {
 			// eslint-disable-next-line no-console
 			console.log(generated.output[0].code);
@@ -337,6 +337,24 @@ describe( 'rollup-plugin-node-resolve', function () {
 		});
 	});
 
+	it( 'warns when importing builtins', function () {
+		return rollup.rollup({
+			input: 'samples/builtins/main.js',
+			onwarn: expectWarnings([{
+				code: 'UNRESOLVED_IMPORT',
+				source: 'path'
+			}]),
+			plugins: [
+				nodeResolve({
+					mainFields: ['browser', 'main'],
+					preferBuiltins: true
+				})
+			]
+		}).then(executeBundle).then(module => {
+			assert.equal(module.exports, require('path').sep);
+		});
+	});
+
 	it( 'allows use of object browser field, resolving nested directories', function () {
 		return rollup.rollup({
 			input: 'samples/browser-object-nested/main.js',