public function testCreateAliases()
{
// Set up file structure.
$testDir = $this->createTempSubDir();
$projectRoot = "{$testDir}/project";
$homeDir = "{$testDir}/home";
mkdir($projectRoot);
mkdir($homeDir);
// Check that aliases are created.
$this->drushHelper->setHomeDir($homeDir);
$this->drushHelper->createAliases($this->project, $projectRoot, $this->environments);
$this->assertFileExists("{$homeDir}/.drush/test.aliases.drushrc.php");
// Check that aliases exist for the 'master' and local environments.
$aliases = [];
include_once "{$homeDir}/.drush/test.aliases.drushrc.php";
$this->assertArrayHasKey('master', $aliases);
$this->assertArrayHasKey('_local', $aliases);
}