[ticket/11579] Add remaining unit tests for validate_data functions

This now includes tests for usernames, passwords, emails, and jabber
addresses. A few small changes had to be applied to phpbb_mock_cache
and phpbb_mock_user in order to incorporate needed methods.

PHPBB3-11579

tests/mock/user.php

@@ -33,4 +33,17 @@ class phpbb_mock_user
 	{
 		$this->options[$item] = $value;
 	}
+
+	public function check_ban($user_id = false, $user_ips = false, $user_email = false, $return = false)
+	{
+		$banned_users = $this->optionget('banned_users');
+		foreach ($banned_users as $banned)
+		{
+			if ($banned == $user_id || $banned == $user_ips || $banned == $user_email)
+			{
+				return true;
+			}
+		}
+		return false;
+	}
 }