Resolve directory to the real path before using as base for resolve (#7)

Close #6

Author: zkochan

fixture/fixture-for-symlinks/subfolder/.gitignore

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

fixture/fixture-for-symlinks/subfolder/node_modules/foo.js

@@ -0,0 +1 @@
+subfolder/symlink-target/

fixture/fixture-for-symlinks/subfolder/symlink-target/.gitkeep

@@ -1,6 +1,7 @@
 'use strict';
 const path = require('path');
 const Module = require('module');
+const fs = require('fs');
 
 const resolveFrom = (fromDir, moduleId, silent) => {
 	if (typeof fromDir !== 'string') {
@@ -11,7 +12,18 @@ const resolveFrom = (fromDir, moduleId, silent) => {
 		throw new TypeError(`Expected \`moduleId\` to be of type \`string\`, got \`${typeof moduleId}\``);
 	}
 
-	fromDir = path.resolve(fromDir);
+	try {
+		fromDir = fs.realpathSync(fromDir);
+	} catch (err) {
+		if (err.code === 'ENOENT') {
+			fromDir = path.resolve(fromDir);
+		} else if (silent) {
+			return null;
+		} else {
+			throw err;
+		}
+	}
+
 	const fromFile = path.join(fromDir, 'noop.js');
 
 	const resolveFileName = () => Module._resolveFilename(moduleId, {

fixture/fixture-for-symlinks/symlink-target

@@ -15,6 +15,8 @@ test('resolveFrom()', t => {
 
 	const resolveFromfixture = m.bind(null, 'fixture');
 	t.regex(resolveFromfixture('./fixture'), /fixture\/fixture\.js$/);
+
+	t.truthy(m('./fixture/fixture-for-symlinks/symlink-target', 'foo'));
 });
 
 test('resolveFrom.silent()', t => {
@@ -23,4 +25,6 @@ test('resolveFrom.silent()', t => {
 
 	const silentResolveFromfixture = m.silent.bind(null, 'fixture');
 	t.regex(silentResolveFromfixture('./fixture'), /fixture\/fixture\.js$/);
+
+	t.is(m.silent('fixture-not-exists', './fixture'), null);
 });