From 1a29f446498969df4ca0a9fef17bb71d35cd1f8a Mon Sep 17 00:00:00 2001
From: Frederic Massart <fred@moodle.com>
Date: Thu, 23 Jul 2015 11:54:46 +0800
Subject: [PATCH] MDL-46232 user: Handle bulk delete of users without email
 addresses

---
 lib/moodlelib.php            |  5 ++++-
 lib/tests/moodlelib_test.php | 28 ++++++++++++++++++++++++++++
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index 69cd39567cb..3cb1fdd7d71 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -3984,8 +3984,11 @@ function delete_user(stdClass $user) {
     // Force logout - may fail if file based sessions used, sorry.
     \core\session\manager::kill_user_sessions($user->id);
 
+    // Generate username from email address, or a fake email.
+    $delemail = !empty($user->email) ? $user->email : $user->username . '.' . $user->id . '@unknownemail.invalid';
+    $delname = clean_param($delemail . "." . time(), PARAM_USERNAME);
+
     // Workaround for bulk deletes of users with the same email address.
-    $delname = clean_param($user->email . "." . time(), PARAM_USERNAME);
     while ($DB->record_exists('user', array('username' => $delname))) { // No need to use mnethostid here.
         $delname++;
     }
diff --git a/lib/tests/moodlelib_test.php b/lib/tests/moodlelib_test.php
index 3d33588a9f0..8ee6dd2d803 100644
--- a/lib/tests/moodlelib_test.php
+++ b/lib/tests/moodlelib_test.php
@@ -1882,6 +1882,10 @@ class core_moodlelib_testcase extends advanced_testcase {
 
         $user = $this->getDataGenerator()->create_user(array('idnumber'=>'abc'));
         $user2 = $this->getDataGenerator()->create_user(array('idnumber'=>'xyz'));
+        $usersharedemail1 = $this->getDataGenerator()->create_user(array('email' => 'sharedemail@example.invalid'));
+        $usersharedemail2 = $this->getDataGenerator()->create_user(array('email' => 'sharedemail@example.invalid'));
+        $useremptyemail1 = $this->getDataGenerator()->create_user(array('email' => ''));
+        $useremptyemail2 = $this->getDataGenerator()->create_user(array('email' => ''));
 
         // Delete user and capture event.
         $sink = $this->redirectEvents();
@@ -1947,6 +1951,30 @@ class core_moodlelib_testcase extends advanced_testcase {
         $result = delete_user($admin);
         $this->assertFalse($result);
 
+        // Simultaneously deleting users with identical email addresses.
+        $result1 = delete_user($usersharedemail1);
+        $result2 = delete_user($usersharedemail2);
+
+        $usersharedemail1after = $DB->get_record('user', array('id' => $usersharedemail1->id));
+        $usersharedemail2after = $DB->get_record('user', array('id' => $usersharedemail2->id));
+        $this->assertTrue($result1);
+        $this->assertTrue($result2);
+        $this->assertStringStartsWith($usersharedemail1->email . '.', $usersharedemail1after->username);
+        $this->assertStringStartsWith($usersharedemail2->email . '.', $usersharedemail2after->username);
+
+        // Simultaneously deleting users without email addresses.
+        $result1 = delete_user($useremptyemail1);
+        $result2 = delete_user($useremptyemail2);
+
+        $useremptyemail1after = $DB->get_record('user', array('id' => $useremptyemail1->id));
+        $useremptyemail2after = $DB->get_record('user', array('id' => $useremptyemail2->id));
+        $this->assertTrue($result1);
+        $this->assertTrue($result2);
+        $this->assertStringStartsWith($useremptyemail1->username . '.' . $useremptyemail1->id . '@unknownemail.invalid.',
+            $useremptyemail1after->username);
+        $this->assertStringStartsWith($useremptyemail2->username . '.' . $useremptyemail2->id . '@unknownemail.invalid.',
+            $useremptyemail2after->username);
+
         $this->resetDebugging();
     }