MDL-51014 behat: Wait for filepicker to load repository

lib/behat/behat_files.php

@@ -193,6 +193,14 @@ protected function open_add_file_window($filemanagernode, $repositoryname) {
         $this->ensure_node_is_visible($add);
         $add->click();
 
+        // Wait for the default repository (if any) to load. This checks that
+        // the relevant div exists and that it does not include the loading image.
+        $this->ensure_element_exists(
+                "//div[contains(concat(' ', normalize-space(@class), ' '), ' file-picker ')]" .
+                "//div[contains(concat(' ', normalize-space(@class), ' '), ' fp-content ')]" .
+                "[not(descendant::div[contains(concat(' ', normalize-space(@class), ' '), ' fp-content-loading ')])]",
+                'xpath_element');
+
         // Getting the repository link and opening it.
         $repoexception = new ExpectationException('The "' . $repositoryname . '" repository has not been found', $this->getSession());
 
@@ -210,7 +218,11 @@ protected function open_add_file_window($filemanagernode, $repositoryname) {
 
         // Selecting the repo.
         $this->ensure_node_is_visible($repositorylink);
-        $repositorylink->click();
+        if (!$repositorylink->getParent()->getParent()->hasClass('active')) {
+            // If the repository link is active, then the repository is already loaded.
+            // Clicking it while it's active causes issues, so only click it when it isn't (see MDL-51014).
+            $repositorylink->click();
+        }
     }
 
     /**