Elgg\ViewsService::viewExists PHP Method

    public function viewExists($view, $viewtype = '', $recurse = true)
    {
        $view = $this->canonicalizeViewName($view);
        if (empty($view) || !is_string($view)) {
            return false;
        }
        // Detect view type
        if ($viewtype === '' || !_elgg_is_valid_viewtype($viewtype)) {
            $viewtype = elgg_get_viewtype();
        }
        $file = $this->findViewFile($view, $viewtype);
        if ($file) {
            return true;
        }
        // If we got here then check whether this exists as an extension
        // We optionally recursively check whether the extended view exists also for the viewtype
        if ($recurse && isset($this->extensions[$view])) {
            foreach ($this->extensions[$view] as $view_extension) {
                // do not recursively check to stay away from infinite loops
                if ($this->viewExists($view_extension, $viewtype, false)) {
                    return true;
                }
            }
        }
        // Now check if the default view exists if the view is registered as a fallback
        if ($viewtype != 'default' && $this->doesViewtypeFallback($viewtype)) {
            return $this->viewExists($view, 'default');
        }
        return false;
    }

 public function testViewsCanExistBasedOnViewtypeFallback()
 {
     $this->views->registerViewtypeFallback('mobile');
     $this->assertTrue($this->views->viewExists('js/interpreted.js', 'mobile'));
     $this->assertEquals('// PHP', $this->views->renderView('js/interpreted.js', array(), false, 'mobile'));
 }