[Fix] Make behavior consistent with require.resolve() for "shadowed" core modules

Backports #148 into v1.

Author: ljharb

lib/async.js

@@ -73,8 +73,8 @@ module.exports = function resolve(x, options, callback) {
             } else loadAsFile(res, opts.package, onfile);
         } else loadNodeModules(x, basedir, function (err, n, pkg) {
             if (err) cb(err);
-            else if (n) cb(null, n, pkg);
             else if (core[x]) return cb(null, x);
+            else if (n) cb(null, n, pkg);
             else {
                 var moduleError = new Error("Cannot find module '" + x + "' from '" + parent + "'");
                 moduleError.code = 'MODULE_NOT_FOUND';

lib/sync.js

@@ -59,6 +59,8 @@ module.exports = function (x, options) {
         if (x === '..' || x.slice(-1) === '/') res += '/';
         var m = loadAsFileSync(res) || loadAsDirectorySync(res);
         if (m) return m;
+    } else if (core[x]) {
+        return x;
     } else {
         var n = loadNodeModulesSync(x, absoluteStart);
         if (n) return n;

test/resolver.js

@@ -283,17 +283,6 @@ test('without basedir', function (t) {
     });
 });
 
-test('#25: node modules with the same name as node stdlib modules', function (t) {
-    t.plan(1);
-
-    var resolverDir = path.join(__dirname, 'resolver/punycode');
-
-    resolve('punycode', { basedir: resolverDir }, function (err, res, pkg) {
-        if (err) t.fail(err);
-        t.equal(res, path.join(resolverDir, 'node_modules/punycode/index.js'));
-    });
-});
-
 test('#52 - incorrectly resolves module-paths like "./someFolder/" when there is a file of the same name', function (t) {
     t.plan(2);
 

test/resolver_sync.js

@@ -184,17 +184,6 @@ test('incorrect main', function (t) {
     t.end();
 });
 
-test('#25: node modules with the same name as node stdlib modules', function (t) {
-    var resolverDir = path.join(__dirname, 'resolver/punycode');
-
-    t.equal(
-        resolve.sync('punycode', { basedir: resolverDir }),
-        path.join(resolverDir, 'node_modules/punycode/index.js')
-    );
-
-    t.end();
-});
-
 var stubStatSync = function stubStatSync(fn) {
     var fs = require('fs');
     var statSync = fs.statSync;

test/shadowed_core.js

@@ -0,0 +1,38 @@
+var test = require('tape');
+var resolve = require('../');
+var path = require('path');
+
+test('shadowed core modules still return core module', function (t) {
+    t.plan(2);
+
+    resolve('util', { basedir: path.join(__dirname, 'shadowed_core') }, function (err, res) {
+        t.ifError(err);
+        t.equal(res, 'util');
+    });
+});
+
+test('shadowed core modules still return core module [sync]', function (t) {
+    t.plan(1);
+
+    var res = resolve.sync('util', { basedir: path.join(__dirname, 'shadowed_core') });
+
+    t.equal(res, 'util');
+});
+
+test('shadowed core modules return shadow when appending `/`', function (t) {
+    t.plan(2);
+
+    resolve('util/', { basedir: path.join(__dirname, 'shadowed_core') }, function (err, res) {
+        t.ifError(err);
+        t.equal(res, path.join(__dirname, 'shadowed_core/node_modules/util/index.js'));
+    });
+});
+
+test('shadowed core modules return shadow when appending `/` [sync]', function (t) {
+    t.plan(1);
+
+    var res = resolve.sync('util/', { basedir: path.join(__dirname, 'shadowed_core') });
+
+    t.equal(res, path.join(__dirname, 'shadowed_core/node_modules/util/index.js'));
+});
+

test/shadowed_core/.gitignore

@@ -0,0 +1 @@
+!/node_modules