class MockAliasManager

class MockAliasManager implements AliasManagerInterface {
    
    /**
     * Array of mocked aliases. Keys are system paths, followed by language.
     *
     * @var array
     */
    protected $aliases = [];
    
    /**
     * Array of mocked aliases. Keys are aliases, followed by language.
     *
     * @var array
     */
    protected $systemPaths = [];
    
    /**
     * An index of aliases that have been requested.
     *
     * @var array
     */
    protected $lookedUp = [];
    
    /**
     * The language to assume a path alias is for if not specified.
     *
     * @var string
     */
    public $defaultLanguage = 'en';
    
    /**
     * Adds an alias to the in-memory alias table for this object.
     *
     * @param string $path
     *   The system path of the alias.
     * @param string $alias
     *   The alias of the system path.
     * @param string $path_language
     *   The language of this alias.
     */
    public function addAlias($path, $alias, $path_language = NULL) {
        $language = $path_language ?: $this->defaultLanguage;
        if ($path[0] !== '/') {
            throw new \InvalidArgumentException('The path needs to start with a slash.');
        }
        if ($alias[0] !== '/') {
            throw new \InvalidArgumentException('The alias needs to start with a slash.');
        }
        $this->aliases[$path][$language] = $alias;
        $this->systemPaths[$alias][$language] = $path;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getPathByAlias($alias, $langcode = NULL) {
        $langcode = $langcode ?: $this->defaultLanguage;
        return $this->systemPaths[$alias][$langcode];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getAliasByPath($path, $langcode = NULL) {
        if ($path[0] !== '/') {
            throw new \InvalidArgumentException(sprintf('Source path %s has to start with a slash.', $path));
        }
        $langcode = $langcode ?: $this->defaultLanguage;
        $this->lookedUp[$path] = 1;
        return $this->aliases[$path][$langcode];
    }
    
    /**
     * {@inheritdoc}
     */
    public function cacheClear($source = NULL) {
        // Not needed.
    }

}