function linkDependencies(projectName) {
  let sourceFixture = dirs[projectName]; // original fixture for this acceptance test.
  let runFixture = quickTemp.makeOrRemake(dirs, `${projectName}-clone`);

  fs.copySync(sourceFixture, runFixture);

  let nodeManifest = fs.readFileSync(path.join(runFixture, 'package.json'));

  let packageCache = new PackageCache(root);
  let packager = hasGlobalYarn ? 'yarn' : 'npm';

  packageCache.create('node', packager, nodeManifest, [{ name: 'ember-cli', path: root }]);

  let nodeModulesPath = path.join(runFixture, 'node_modules');
  symlinkOrCopySync(path.join(packageCache.get('node'), 'node_modules'), nodeModulesPath);

  process.chdir(runFixture);

  return runFixture;
}
Creates symbolic links from the dependency temp directories
to the project that is under test.

@method linkDependencies
@param  {String} projectName The name of the project under test
@return {String} The path to the hydrated fixture.