1  'use strict';
 2  const path = require('path');
 3  const resolveCwd = require('resolve-cwd');
 4  const pkgDir = require('pkg-dir');
 5  
 6  module.exports = filename => {
 7  	const globalDir = pkgDir.sync(path.dirname(filename));
 8  	const relativePath = path.relative(globalDir, filename);
 9  	const pkg = require(path.join(globalDir, 'package.json'));
10  	const localFile = resolveCwd.silent(path.join(pkg.name, relativePath));
11  	const localNodeModules = path.join(process.cwd(), 'node_modules');
12  
13  	const filenameInLocalNodeModules = !path.relative(localNodeModules, filename).startsWith('..') &&
14  		// On Windows, if `localNodeModules` and `filename` are on different partitions, `path.relative()` returns the value of `filename`, resulting in `filenameInLocalNodeModules` incorrectly becoming `true`.
15  		path.parse(localNodeModules).root === path.parse(filename).root;
16  
17  	// Use `path.relative()` to detect local package installation,
18  	// because __filename's case is inconsistent on Windows
19  	// Can use `===` when targeting Node.js 8
20  	// See https://github.com/nodejs/node/issues/6624
21  	return !filenameInLocalNodeModules && localFile && path.relative(localFile, filename) !== '' && require(localFile);
22  };