diff --git a/plugins/acl/acl.php b/plugins/acl/acl.php
index 451edad4c..d1ec4f6c5 100644
--- a/plugins/acl/acl.php
+++ b/plugins/acl/acl.php
@@ -597,7 +597,7 @@ class acl extends rcube_plugin
 
         $out = $this->list_rights();
 
-        $out = preg_replace(array('/^<table[^>]+>/', '/<\/table>$/'), '', $out);
+        $out = preg_replace(['/^<table[^>]+>/', '/<\/table>$/'], '', $out);
 
         $this->rc->output->command('acl_list_update', $out);
     }
diff --git a/plugins/additional_message_headers/additional_message_headers.php b/plugins/additional_message_headers/additional_message_headers.php
index 1861aa319..b20f9bc0d 100644
--- a/plugins/additional_message_headers/additional_message_headers.php
+++ b/plugins/additional_message_headers/additional_message_headers.php
@@ -7,7 +7,7 @@
  * to or remove them from outgoing messages.
  *
  * Enable the plugin in config.inc.php and add your desired headers:
- * $config['additional_message_headers'] = array('User-Agent' => 'My-Very-Own-Webmail');
+ * $config['additional_message_headers'] = ['User-Agent' => 'My-Very-Own-Webmail'];
  *
  * @author Ziba Scott
  * @website http://roundcube.net
diff --git a/plugins/attachment_reminder/localization/en_US.inc b/plugins/attachment_reminder/localization/en_US.inc
index b1fdc9e37..17e775968 100644
--- a/plugins/attachment_reminder/localization/en_US.inc
+++ b/plugins/attachment_reminder/localization/en_US.inc
@@ -13,7 +13,6 @@
  For translation see https://www.transifex.com/projects/p/roundcube-webmail/resource/plugin-attachment_reminder/
 */
 
-$messages = array();
 $messages['missingattachment'] = "Missing attachment?";
 $messages['forgotattachment'] = "Did you forget to attach a file?";
 $messages['reminderoption'] = "Remind about forgotten attachments";
diff --git a/plugins/enigma/enigma.php b/plugins/enigma/enigma.php
index 504432eef..19f60bedd 100644
--- a/plugins/enigma/enigma.php
+++ b/plugins/enigma/enigma.php
@@ -78,7 +78,7 @@ class enigma extends rcube_plugin
 
             // register handler for keys/certs management
             $this->register_action('plugin.enigmakeys', [$this, 'preferences_ui']);
-//            $this->register_action('plugin.enigmacerts', array($this, 'preferences_ui'));
+//            $this->register_action('plugin.enigmacerts', [$this, 'preferences_ui']);
 
             $this->load_ui();
 
@@ -371,7 +371,7 @@ class enigma extends rcube_plugin
             $field_id = 'rcmfd_enigma_password_time';
             $select   = new html_select(['name' => '_enigma_password_time', 'id' => $field_id, 'class' => 'custom-select']);
 
-            foreach (array(1, 5, 10, 15, 30) as $m) {
+            foreach ([1, 5, 10, 15, 30] as $m) {
                 $label = $this->gettext(['name' => 'nminutes', 'vars' => ['m' => $m]]);
                 $select->add($label, $m);
             }
diff --git a/plugins/enigma/lib/enigma_driver_gnupg.php b/plugins/enigma/lib/enigma_driver_gnupg.php
index def197639..1c14946e5 100644
--- a/plugins/enigma/lib/enigma_driver_gnupg.php
+++ b/plugins/enigma/lib/enigma_driver_gnupg.php
@@ -700,7 +700,7 @@ class enigma_driver_gnupg extends enigma_driver
                 }
 
                 $unique = ['user_id' => $this->rc->user->ID, 'context' => 'enigma', 'filename' => $filename];
-                $result = $db->insert_or_update($table, $unique, array('mtime', 'data'), array($mtime, $data));
+                $result = $db->insert_or_update($table, $unique, ['mtime', 'data'], [$mtime, $data]);
 
                 if ($db->is_error($result)) {
                     rcube::raise_error([
diff --git a/plugins/enigma/lib/enigma_ui.php b/plugins/enigma/lib/enigma_ui.php
index 74f39bb28..d5438280a 100644
--- a/plugins/enigma/lib/enigma_ui.php
+++ b/plugins/enigma/lib/enigma_ui.php
@@ -1200,7 +1200,7 @@ class enigma_ui
 
         if ($mode && ($status instanceof enigma_error)) {
             $code = $status->getCode();
-            $vars = array();
+            $vars = [];
 
             if ($code == enigma_error::KEYNOTFOUND) {
                 if ($email = $status->getData('missing')) {
diff --git a/plugins/krb_authentication/config.inc.php.dist b/plugins/krb_authentication/config.inc.php.dist
index 975cacb85..b1c1ffb9e 100644
--- a/plugins/krb_authentication/config.inc.php.dist
+++ b/plugins/krb_authentication/config.inc.php.dist
@@ -12,9 +12,9 @@ $config['krb_authentication_host'] = '';
 // GSSAPI security context.
 // Single value or an array with per-protocol values. Example:
 //
-//   $config['krb_authentication_context'] = array(
+//   $config['krb_authentication_context'] = [
 //       'imap'  => 'imap/host.fqdn@REALM.NAME',
 //       'smtp'  => 'smtp/host.fqdn@REALM.NAME',
 //       'sieve' => 'sieve/host.fqdn@REALM.NAME',
-//   );
+//   ];
 $config['krb_authentication_context'] = 'principal@REALM.NAME';
diff --git a/plugins/markasjunk/drivers/cmd_learn.php b/plugins/markasjunk/drivers/cmd_learn.php
index 4d81c536a..83ee0abae 100644
--- a/plugins/markasjunk/drivers/cmd_learn.php
+++ b/plugins/markasjunk/drivers/cmd_learn.php
@@ -76,7 +76,7 @@ class markasjunk_cmd_learn
                 preg_match_all('/%h:([\w_-]+)/', $tmp_command, $header_names, PREG_SET_ORDER);
                 foreach ($header_names as $header) {
                     $val = null;
-                    if ($msg = $storage->conn->fetchHeader($src_mbox, $uid, true, false, array($header[1]))) {
+                    if ($msg = $storage->conn->fetchHeader($src_mbox, $uid, true, false, [$header[1]])) {
                         $val = !empty($msg->{$header[1]}) ? $msg->{$header[1]} : $msg->others[$header[1]];
                     }
 
diff --git a/plugins/password/drivers/cpanel_webmail.php b/plugins/password/drivers/cpanel_webmail.php
index d08170c26..47e5896f5 100644
--- a/plugins/password/drivers/cpanel_webmail.php
+++ b/plugins/password/drivers/cpanel_webmail.php
@@ -105,10 +105,10 @@ class rcube_cpanel_webmail_password
      * Example:
      *
      * <code>
-     * curl_auth_post('john:Secr3t', 'https://example.org', array(
+     * curl_auth_post('john:Secr3t', 'https://example.org', [
      *     'param' => 'value',
      *     'param' => 'value'
-     * ));
+     * ]);
      * </code>
      *
      * @param string $userpwd  user name and password separated by a colon
diff --git a/plugins/password/drivers/pwned.php b/plugins/password/drivers/pwned.php
index 0152bd453..2624fbd67 100644
--- a/plugins/password/drivers/pwned.php
+++ b/plugins/password/drivers/pwned.php
@@ -176,7 +176,7 @@ class rcube_pwned_password
         curl_setopt($ch, CURLOPT_URL, $url);
         curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
         if (self::ENHANCED_PRIVACY_CURL == 1) {
-            curl_setopt($ch, CURLOPT_HTTPHEADER, array('Add-Padding: true'));
+            curl_setopt($ch, CURLOPT_HTTPHEADER, ['Add-Padding: true']);
         }
         $output = curl_exec($ch);
         curl_close($ch);
diff --git a/plugins/redundant_attachments/redundant_attachments.php b/plugins/redundant_attachments/redundant_attachments.php
index 172bc8914..783c235d7 100644
--- a/plugins/redundant_attachments/redundant_attachments.php
+++ b/plugins/redundant_attachments/redundant_attachments.php
@@ -91,7 +91,8 @@ class redundant_attachments extends filesystem_attachments
      */
     private function _key($args)
     {
-        $uname = $args['path'] ?: $args['name'];
+        $uname = !empty($args['path']) ? $args['path'] : $args['name'];
+
         return $args['group'] . md5(microtime() . $uname . $_SESSION['user_id']);
     }
 
@@ -130,7 +131,7 @@ class redundant_attachments extends filesystem_attachments
 
         $this->_load_drivers();
 
-        $data = $args['path'] ? file_get_contents($args['path']) : $args['data'];
+        $data = !empty($args['path']) ? file_get_contents($args['path']) : $args['data'];
 
         $args['data'] = null;
 
@@ -193,8 +194,9 @@ class redundant_attachments extends filesystem_attachments
         // attempt to get file from local file system
         $args = parent::get($args);
 
-        if ($args['path'] && ($args['status'] = file_exists($args['path'])))
-          return $args;
+        if (!empty($args['path']) && ($args['status'] = file_exists($args['path']))) {
+            return $args;
+        }
 
         $this->_load_drivers();
 
diff --git a/plugins/show_additional_headers/show_additional_headers.php b/plugins/show_additional_headers/show_additional_headers.php
index 87de51fca..1a48f8b76 100644
--- a/plugins/show_additional_headers/show_additional_headers.php
+++ b/plugins/show_additional_headers/show_additional_headers.php
@@ -7,44 +7,50 @@
  * and display them in the message view.
  *
  * Enable the plugin in config.inc.php and add your desired headers:
- *   $config['show_additional_headers'] = array('User-Agent');
+ *   $config['show_additional_headers'] = ['User-Agent'];
  *
  * @author Thomas Bruederli
  * @license GNU GPLv3+
  */
 class show_additional_headers extends rcube_plugin
 {
-  public $task = 'mail';
+    public $task = 'mail';
 
-  function init()
-  {
-    $rcmail = rcmail::get_instance();
-    if ($rcmail->action == 'show' || $rcmail->action == 'preview') {
-      $this->add_hook('storage_init', array($this, 'storage_init'));
-      $this->add_hook('message_headers_output', array($this, 'message_headers'));
-    } else if ($rcmail->action == '') {
-      // with enabled_caching we're fetching additional headers before show/preview
-      $this->add_hook('storage_init', array($this, 'storage_init'));
-    }
-  }
+    function init()
+    {
+        $rcmail = rcmail::get_instance();
 
-  function storage_init($p)
-  {
-    $rcmail = rcmail::get_instance();
-    if ($add_headers = (array)$rcmail->config->get('show_additional_headers', array()))
-      $p['fetch_headers'] = trim($p['fetch_headers'].' ' . strtoupper(join(' ', $add_headers)));
-
-    return $p;
-  }
-
-  function message_headers($p)
-  {
-    $rcmail = rcmail::get_instance();
-    foreach ((array)$rcmail->config->get('show_additional_headers', array()) as $header) {
-      if ($value = $p['headers']->get($header))
-        $p['output'][$header] = array('title' => $header, 'value' => $value);
+        if ($rcmail->action == 'show' || $rcmail->action == 'preview') {
+            $this->add_hook('storage_init', [$this, 'storage_init']);
+            $this->add_hook('message_headers_output', [$this, 'message_headers']);
+        }
+        else if ($rcmail->action == '') {
+            // with enabled_caching we're fetching additional headers before show/preview
+            $this->add_hook('storage_init', [$this, 'storage_init']);
+        }
     }
 
-    return $p;
-  }
+    function storage_init($p)
+    {
+        $rcmail = rcmail::get_instance();
+
+        if ($add_headers = (array) $rcmail->config->get('show_additional_headers', [])) {
+            $p['fetch_headers'] = trim($p['fetch_headers']. ' ' . strtoupper(join(' ', $add_headers)));
+        }
+
+        return $p;
+    }
+
+    function message_headers($p)
+    {
+        $rcmail = rcmail::get_instance();
+
+        foreach ((array) $rcmail->config->get('show_additional_headers', []) as $header) {
+            if ($value = $p['headers']->get($header)) {
+                $p['output'][$header] = ['title' => $header, 'value' => $value];
+            }
+        }
+
+        return $p;
+    }
 }
diff --git a/plugins/show_additional_headers/tests/ShowAdditionalHeaders.php b/plugins/show_additional_headers/tests/ShowAdditionalHeaders.php
index d2a84a709..36dbd74a1 100644
--- a/plugins/show_additional_headers/tests/ShowAdditionalHeaders.php
+++ b/plugins/show_additional_headers/tests/ShowAdditionalHeaders.php
@@ -20,4 +20,3 @@ class ShowAdditionalHeaders_Plugin extends PHPUnit\Framework\TestCase
         $this->assertInstanceOf('rcube_plugin', $plugin);
     }
 }
-
diff --git a/plugins/squirrelmail_usercopy/squirrelmail_usercopy.php b/plugins/squirrelmail_usercopy/squirrelmail_usercopy.php
index d8bab8990..e4ba6ef4b 100644
--- a/plugins/squirrelmail_usercopy/squirrelmail_usercopy.php
+++ b/plugins/squirrelmail_usercopy/squirrelmail_usercopy.php
@@ -12,12 +12,12 @@ class squirrelmail_usercopy extends rcube_plugin
 
     private $prefs            = null;
     private $identities_level = 0;
-    private $abook            = array();
+    private $abook            = [];
 
     public function init()
     {
-        $this->add_hook('user_create', array($this, 'create_user'));
-        $this->add_hook('identity_create', array($this, 'create_identity'));
+        $this->add_hook('user_create', [$this, 'create_user']);
+        $this->add_hook('identity_create', [$this, 'create_identity']);
     }
 
     public function create_user($p)
@@ -29,9 +29,11 @@ class squirrelmail_usercopy extends rcube_plugin
 
         // read prefs and add email address
         $this->read_squirrel_prefs($p['user']);
-        if (($this->identities_level == 0 || $this->identities_level == 2)
+
+        if (
+            ($this->identities_level == 0 || $this->identities_level == 2)
             && $rcmail->config->get('squirrelmail_set_alias')
-            && $this->prefs['email_address']
+            && !empty($this->prefs['email_address'])
         ) {
             $p['user_email'] = $this->prefs['email_address'];
         }
@@ -45,45 +47,49 @@ class squirrelmail_usercopy extends rcube_plugin
 
         // prefs are set in create_user()
         if ($this->prefs) {
-            if ($this->prefs['full_name']) {
+            if (!empty($this->prefs['full_name'])) {
                 $p['record']['name'] = $this->prefs['full_name'];
             }
 
-            if (($this->identities_level == 0 || $this->identities_level == 2) && $this->prefs['email_address']) {
+            if (
+                ($this->identities_level == 0 || $this->identities_level == 2)
+                && !empty($this->prefs['email_address'])
+            ) {
                 $p['record']['email'] = $this->prefs['email_address'];
             }
 
-            if ($this->prefs['___signature___']) {
+            if (!empty($this->prefs['___signature___'])) {
                 $p['record']['signature'] = $this->prefs['___signature___'];
             }
 
-            if ($this->prefs['reply_to']) {
+            if (!empty($this->prefs['reply_to'])) {
                 $p['record']['reply-to'] = $this->prefs['reply_to'];
             }
 
-            if (($this->identities_level == 0 || $this->identities_level == 1)
+            if (
+                ($this->identities_level == 0 || $this->identities_level == 1)
                 && isset($this->prefs['identities']) && $this->prefs['identities'] > 1
             ) {
                 for ($i = 1; $i < $this->prefs['identities']; $i++) {
                     unset($ident_data);
-                    $ident_data = array('name' => '', 'email' => ''); // required data
+                    $ident_data = ['name' => '', 'email' => '']; // required data
 
-                    if ($this->prefs['full_name'.$i]) {
+                    if (!empty($this->prefs['full_name'.$i])) {
                         $ident_data['name'] = $this->prefs['full_name'.$i];
                     }
 
-                    if ($this->identities_level == 0 && $this->prefs['email_address'.$i]) {
+                    if ($this->identities_level == 0 && !empty($this->prefs['email_address'.$i])) {
                         $ident_data['email'] = $this->prefs['email_address'.$i];
                     }
                     else {
                         $ident_data['email'] = $p['record']['email'];
                     }
 
-                    if ($this->prefs['reply_to'.$i]) {
+                    if (!empty($this->prefs['reply_to'.$i])) {
                         $ident_data['reply-to'] = $this->prefs['reply_to'.$i];
                     }
 
-                    if ($this->prefs['___sig'.$i.'___']) {
+                    if (!empty($this->prefs['___sig'.$i.'___'])) {
                         $ident_data['signature'] = $this->prefs['___sig'.$i.'___'];
                     }
 
@@ -94,8 +100,8 @@ class squirrelmail_usercopy extends rcube_plugin
 
             // copy address book
             $contacts  = $rcmail->get_address_book(null, true);
-            $addresses = array();
-            $groups    = array();
+            $addresses = [];
+            $groups    = [];
 
             if ($contacts && !empty($this->abook)) {
                 foreach ($this->abook as $rec) {
@@ -106,25 +112,31 @@ class squirrelmail_usercopy extends rcube_plugin
 
                     // create group for addresses
                     if (count($emails) > 1) {
-                        if (!($group_id = $groups[$rec['name']])) {
-                            if ($group = $contacts->create_group($rec['name'])) {
-                                $group_id = $group['id'];
-                                $groups[$rec['name']] = $group_id;
-                            }
+                        if (!empty($groups[$rec['name']])) {
+                            $group_id = $groups[$rec['name']];
+                        }
+                        else if ($group = $contacts->create_group($rec['name'])) {
+                            $group_id = $group['id'];
+                            $groups[$rec['name']] = $group_id;
                         }
                     }
 
                     // create contacts
                     foreach ($emails as $email) {
-                        if (!($contact_id = $addresses[$email]) && rcube_utils::check_email(rcube_utils::idn_to_ascii($email))) {
+                        $contact_id = null;
+
+                        if (!empty($addresses[$email])) {
+                            $contact_id = $addresses[$email];
+                        }
+                        else if (rcube_utils::check_email(rcube_utils::idn_to_ascii($email))) {
                             $rec['email'] = rcube_utils::idn_to_utf8($email);
                             if ($contact_id = $contacts->insert($rec, true)) {
                                 $addresses[$email] = $contact_id;
                             }
                         }
 
-                        if ($group_id && $contact_id) {
-                            $contacts->add_to_group($group_id, array($contact_id));
+                        if (!empty($group_id) && !empty($contact_id)) {
+                            $contacts->add_to_group($group_id, [$contact_id]);
                         }
                     }
                 }
@@ -169,9 +181,9 @@ class squirrelmail_usercopy extends rcube_plugin
             $sigbase   = slashify($srcdir) . $uname . '.si';
 
             if (is_readable($prefsfile)) {
-                $this->prefs = array();
+                $this->prefs = [];
                 foreach (file($prefsfile) as $line) {
-                    list($key, $value) = explode('=', $line);
+                    list($key, $value) = rcube_utils::explode('=', $line);
                     $this->prefs[$key] = $this->convert_charset(rtrim($value), $file_charset);
                 }
 
@@ -193,19 +205,17 @@ class squirrelmail_usercopy extends rcube_plugin
 
                 // parse address book file
                 if (filesize($abookfile)) {
-
                     foreach (file($abookfile) as $line) {
-
                         $line = $this->convert_charset(rtrim($line), $file_charset);
                         $line = str_getcsv($line, "|");
 
-                        $rec = array(
+                        $rec = [
                             'name'      => $line[0],
                             'firstname' => $line[1],
                             'surname'   => $line[2],
                             'email'     => $line[3],
                             'notes'     => $line[4],
-                        );
+                        ];
 
                         if ($rec['name'] && $rec['email']) {
                             $this->abook[] = $rec;
@@ -215,8 +225,8 @@ class squirrelmail_usercopy extends rcube_plugin
             }
         }
         // Database backend
-        else if ($rcmail->config->get('squirrelmail_driver') == 'sql') { 
-            $this->prefs = array();
+        else if ($rcmail->config->get('squirrelmail_driver') == 'sql') {
+            $this->prefs = [];
 
             // connect to squirrelmail database
             $db = rcube_db::factory($rcmail->config->get('squirrelmail_dsn'));
@@ -230,7 +240,7 @@ class squirrelmail_usercopy extends rcube_plugin
             $db_charset      = $rcmail->config->get('squirrelmail_db_charset');
 
             if ($db_charset) {
-                $db->query('SET NAMES '.$db_charset);
+                $db->query('SET NAMES ' . $db_charset);
             }
 
             $sql_result = $db->query('SELECT * FROM ' . $db->quote_identifier($userprefs_table)
diff --git a/plugins/squirrelmail_usercopy/tests/SquirrelmailUsercopy.php b/plugins/squirrelmail_usercopy/tests/SquirrelmailUsercopy.php
index f7929af8e..96aa578b2 100644
--- a/plugins/squirrelmail_usercopy/tests/SquirrelmailUsercopy.php
+++ b/plugins/squirrelmail_usercopy/tests/SquirrelmailUsercopy.php
@@ -20,4 +20,3 @@ class SquirrelmailUsercopy_Plugin extends PHPUnit\Framework\TestCase
         $this->assertInstanceOf('rcube_plugin', $plugin);
     }
 }
-
diff --git a/plugins/subscriptions_option/localization/en_US.inc b/plugins/subscriptions_option/localization/en_US.inc
index f4008f8d6..85d624038 100644
--- a/plugins/subscriptions_option/localization/en_US.inc
+++ b/plugins/subscriptions_option/localization/en_US.inc
@@ -14,5 +14,4 @@
  For translation see https://www.transifex.com/projects/p/roundcube-webmail/resource/plugin-subscriptions_option/
 */
 
-$labels = array();
 $labels['useimapsubscriptions']  = 'Use IMAP Subscriptions';
diff --git a/plugins/subscriptions_option/subscriptions_option.php b/plugins/subscriptions_option/subscriptions_option.php
index 06e72e78a..64b7446cd 100644
--- a/plugins/subscriptions_option/subscriptions_option.php
+++ b/plugins/subscriptions_option/subscriptions_option.php
@@ -10,7 +10,7 @@
  * Add it to the plugins list in config.inc.php to enable the user option
  * The user option can be hidden and set globally by adding 'use_subscriptions'
  * to the 'dont_override' configure line:
- * $config['dont_override'] = array('use_subscriptions');
+ * $config['dont_override'] = ['use_subscriptions'];
  * and then set the global preference
  * $config['use_subscriptions'] = true; // or false
  *
@@ -26,35 +26,54 @@ class subscriptions_option extends rcube_plugin
 {
     public $task = 'mail|settings';
 
+    /**
+     * Plugin initialization
+     */
     function init()
     {
-        $dont_override = rcmail::get_instance()->config->get('dont_override', array());
+        $dont_override = rcmail::get_instance()->config->get('dont_override', []);
+
         if (!in_array('use_subscriptions', $dont_override)) {
-            $this->add_hook('preferences_list', array($this, 'settings_blocks'));
-            $this->add_hook('preferences_save', array($this, 'save_prefs'));
+            $this->add_hook('preferences_list', [$this, 'prefs_list']);
+            $this->add_hook('preferences_save', [$this, 'prefs_save']);
         }
-        $this->add_hook('storage_folders', array($this, 'mailboxes_list'));
-        $this->add_hook('folders_list', array($this, 'folders_list'));
+
+        $this->add_hook('storage_folders', [$this, 'mailboxes_list']);
+        $this->add_hook('folders_list', [$this, 'folders_list']);
     }
 
-    function settings_blocks($args)
+    /**
+     * Hook to inject plugin-specific user settings
+     *
+     * @param array $args Hook arguments
+     *
+     * @return array Modified hook arguments
+     */
+    function prefs_list($args)
     {
         if ($args['section'] == 'server') {
             $this->add_texts('localization/', false);
             $use_subscriptions = rcmail::get_instance()->config->get('use_subscriptions', true);
             $field_id = 'rcmfd_use_subscriptions';
-            $checkbox = new html_checkbox(array('name' => '_use_subscriptions', 'id' => $field_id, 'value' => 1));
+            $checkbox = new html_checkbox(['name' => '_use_subscriptions', 'id' => $field_id, 'value' => 1]);
 
-            $args['blocks']['main']['options']['use_subscriptions'] = array(
-                'title' => html::label($field_id, rcube::Q($this->gettext('useimapsubscriptions'))),
-                'content' => $checkbox->show($use_subscriptions?1:0),
-            );
+            $args['blocks']['main']['options']['use_subscriptions'] = [
+                'title'   => html::label($field_id, rcube::Q($this->gettext('useimapsubscriptions'))),
+                'content' => $checkbox->show($use_subscriptions ? 1 : 0),
+            ];
         }
 
         return $args;
     }
 
-    function save_prefs($args)
+    /**
+     * Hook to save plugin-specific user settings
+     *
+     * @param array $args Hook arguments
+     *
+     * @return array Modified hook arguments
+     */
+    function prefs_save($args)
     {
         if ($args['section'] == 'server') {
             $rcmail = rcmail::get_instance();
@@ -63,10 +82,12 @@ class subscriptions_option extends rcube_plugin
             $args['prefs']['use_subscriptions'] = isset($_POST['_use_subscriptions']);
 
             // if the use_subscriptions preference changes, flush the folder cache
-            if (($use_subscriptions && !isset($_POST['_use_subscriptions'])) ||
-                (!$use_subscriptions && isset($_POST['_use_subscriptions']))) {
-                    $storage = $rcmail->get_storage();
-                    $storage->clear_cache('mailboxes');
+            if (
+                ($use_subscriptions && !isset($_POST['_use_subscriptions']))
+                || (!$use_subscriptions && isset($_POST['_use_subscriptions']))
+            ) {
+                $storage = $rcmail->get_storage();
+                $storage->clear_cache('mailboxes');
             }
         }
 
diff --git a/plugins/subscriptions_option/tests/SubscriptionsOption.php b/plugins/subscriptions_option/tests/SubscriptionsOption.php
index bbb573fda..a293d1bc0 100644
--- a/plugins/subscriptions_option/tests/SubscriptionsOption.php
+++ b/plugins/subscriptions_option/tests/SubscriptionsOption.php
@@ -1,6 +1,6 @@
 <?php
 
-class SubscriptionsOption_Plugin extends PHPUnit\Framework\TestCase
+class SubscriptionsOption_Plugin extends ActionTestCase
 {
 
     function setUp()
@@ -19,5 +19,60 @@ class SubscriptionsOption_Plugin extends PHPUnit\Framework\TestCase
         $this->assertInstanceOf('subscriptions_option', $plugin);
         $this->assertInstanceOf('rcube_plugin', $plugin);
     }
-}
 
+    /**
+     * Test prefs_list() method
+     */
+    function test_prefs_list()
+    {
+        $rcube  = rcube::get_instance();
+        $plugin = new subscriptions_option($rcube->plugins);
+
+        html::$doctype = 'html5';
+
+        $args = ['section' => 'server', 'blocks' => ['main' => ['options' => []]]];
+
+        $result = $plugin->prefs_list($args);
+
+        $this->assertSame(
+            '<label for="rcmfd_use_subscriptions">Use IMAP Subscriptions</label>',
+            $result['blocks']['main']['options']['use_subscriptions']['title']
+        );
+
+        $this->assertSame(
+            '<input name="_use_subscriptions" id="rcmfd_use_subscriptions" value="1" checked type="checkbox">',
+            $result['blocks']['main']['options']['use_subscriptions']['content']
+        );
+    }
+
+    /**
+     * Test prefs_save() method
+     */
+    function test_prefs_save()
+    {
+        self::initStorage();
+
+        $rcube  = rcube::get_instance();
+        $plugin = new subscriptions_option($rcube->plugins);
+
+        $_POST = ['_use_subscriptions' => 1];
+        $args  = ['section' => 'server', 'prefs' => []];
+
+        $result = $plugin->prefs_save($args);
+
+        $this->assertSame(true, $result['prefs']['use_subscriptions']);
+
+        $storage = $rcube->storage;
+        $storage->registerFunction('clear_cache', true);
+
+        $_POST = [];
+        $args  = ['section' => 'server', 'prefs' => []];
+
+        $result = $plugin->prefs_save($args);
+
+        $this->assertSame(false, $result['prefs']['use_subscriptions']);
+        $this->assertCount(1, $storage->methodCalls);
+        $this->assertSame('clear_cache', $storage->methodCalls[0]['name']);
+        $this->assertSame(['mailboxes'], $storage->methodCalls[0]['args']);
+    }
+}
diff --git a/plugins/userinfo/localization/en_US.inc b/plugins/userinfo/localization/en_US.inc
index 070a9e3db..86b5e8ac7 100644
--- a/plugins/userinfo/localization/en_US.inc
+++ b/plugins/userinfo/localization/en_US.inc
@@ -14,7 +14,6 @@
  For translation see https://www.transifex.com/projects/p/roundcube-webmail/resource/plugin-userinfo/
 */
 
-$labels = array();
 $labels['userinfo'] = 'User info';
 $labels['infoforuser'] = 'Info for $user';
 $labels['created'] = 'Created';
diff --git a/plugins/userinfo/userinfo.php b/plugins/userinfo/userinfo.php
index b801e6415..41125d0b2 100644
--- a/plugins/userinfo/userinfo.php
+++ b/plugins/userinfo/userinfo.php
@@ -12,26 +12,26 @@ class userinfo extends rcube_plugin
 
     function init()
     {
-        $this->add_texts('localization/', array('userinfo'));
-        $this->add_hook('settings_actions', array($this, 'settings_actions'));
-        $this->register_action('plugin.userinfo', array($this, 'infostep'));
+        $this->add_texts('localization/', ['userinfo']);
+        $this->add_hook('settings_actions', [$this, 'settings_actions']);
+        $this->register_action('plugin.userinfo', [$this, 'infostep']);
     }
 
     function settings_actions($args)
     {
-        $args['actions'][] = array(
+        $args['actions'][] = [
             'action' => 'plugin.userinfo',
             'class'  => 'userinfo',
             'label'  => 'userinfo',
             'domain' => 'userinfo',
-        );
+        ];
 
         return $args;
     }
 
     function infostep()
     {
-        $this->register_handler('plugin.body', array($this, 'infohtml'));
+        $this->register_handler('plugin.body', [$this, 'infohtml']);
 
         $rcmail = rcmail::get_instance();
         $rcmail->output->set_pagetitle($this->gettext('userinfo'));
@@ -44,7 +44,7 @@ class userinfo extends rcube_plugin
         $user     = $rcmail->user;
         $identity = $user->get_identity();
 
-        $table = new html_table(array('cols' => 2, 'class' => 'propform'));
+        $table = new html_table(['cols' => 2, 'class' => 'propform']);
 
         $table->add('title', html::label('', rcube::Q($this->gettext('userid'))));
         $table->add('', rcube::Q($user->ID));
@@ -64,11 +64,12 @@ class userinfo extends rcube_plugin
         $table->add('title', html::label('', rcube::Q($this->gettext('defaultidentity'))));
         $table->add('', rcube::Q($identity['name'] . ' <' . $identity['email'] . '>'));
 
-        $legend = rcube::Q($this->gettext(array('name' => 'infoforuser', 'vars' => array('user' => $user->get_username()))));
+        $legend = rcube::Q($this->gettext(['name' => 'infoforuser', 'vars' => ['user' => $user->get_username()]]));
         $out    = html::tag('fieldset', '', html::tag('legend', '', $legend) . $table->show());
 
-        return html::div(array('class' => 'box formcontent'),
-            html::div(array('class' => 'boxtitle'), $this->gettext('userinfo'))
-            . html::div(array('class' => 'boxcontent'), $out));
+        return html::div(['class' => 'box formcontent'],
+            html::div(['class' => 'boxtitle'], $this->gettext('userinfo'))
+            . html::div(['class' => 'boxcontent'], $out)
+        );
     }
 }
diff --git a/plugins/vcard_attachments/localization/en_US.inc b/plugins/vcard_attachments/localization/en_US.inc
index e891776a0..d3f3fa019 100644
--- a/plugins/vcard_attachments/localization/en_US.inc
+++ b/plugins/vcard_attachments/localization/en_US.inc
@@ -14,7 +14,6 @@
  For translation see https://www.transifex.com/projects/p/roundcube-webmail/resource/plugin-vcard_attachments/
 */
 
-$labels = array();
 $labels['addvcardmsg'] = 'Add vCard to addressbook';
 $labels['vcardsavefailed'] = 'Unable to save vCard';
 $labels['attachvcard'] = 'Attach vCard';
diff --git a/plugins/vcard_attachments/tests/VcardAttachments.php b/plugins/vcard_attachments/tests/VcardAttachments.php
index 7dde2f224..d51a65ca2 100644
--- a/plugins/vcard_attachments/tests/VcardAttachments.php
+++ b/plugins/vcard_attachments/tests/VcardAttachments.php
@@ -19,5 +19,32 @@ class VcardAttachments_Plugin extends PHPUnit\Framework\TestCase
         $this->assertInstanceOf('vcard_attachments', $plugin);
         $this->assertInstanceOf('rcube_plugin', $plugin);
     }
-}
 
+    /**
+     * Test is_vcard()
+     */
+    function test_is_vcard()
+    {
+        $rcube  = rcube::get_instance();
+        $plugin = new vcard_attachments($rcube->plugins);
+
+        $part = new rcube_message_part();
+        $this->assertFalse(invokeMethod($plugin, 'is_vcard', [$part]));
+
+        $part->mimetype = 'text/vcard';
+        $this->assertTrue(invokeMethod($plugin, 'is_vcard', [$part]));
+
+        $part->mimetype = 'text/x-vcard';
+        $this->assertTrue(invokeMethod($plugin, 'is_vcard', [$part]));
+
+        $part->mimetype = 'text/directory';
+        $this->assertFalse(invokeMethod($plugin, 'is_vcard', [$part]));
+
+        $part->ctype_parameters['profile'] = 'vcard';
+        $this->assertTrue(invokeMethod($plugin, 'is_vcard', [$part]));
+
+        $part->ctype_parameters['profile'] = 'unknown';
+        $part->filename = 'vcard.vcf';
+        $this->assertTrue(invokeMethod($plugin, 'is_vcard', [$part]));
+    }
+}
diff --git a/plugins/vcard_attachments/vcard_attachments.php b/plugins/vcard_attachments/vcard_attachments.php
index fa8571611..dff39cd18 100644
--- a/plugins/vcard_attachments/vcard_attachments.php
+++ b/plugins/vcard_attachments/vcard_attachments.php
@@ -13,9 +13,12 @@ class vcard_attachments extends rcube_plugin
 
     private $abook;
     private $message;
-    private $vcard_parts  = array();
-    private $vcard_bodies = array();
+    private $vcard_parts  = [];
+    private $vcard_bodies = [];
 
+    /**
+     * Plugin initialization
+     */
     function init()
     {
         $rcmail = rcmail::get_instance();
@@ -25,25 +28,25 @@ class vcard_attachments extends rcube_plugin
             $this->add_texts('localization', !$rcmail->output->ajax_call);
             $this->include_stylesheet($skin_path . '/style.css');
             $this->include_script('vcardattach.js');
-            $this->add_button(
-                array(
+            $this->add_button([
                     'type'     => 'link-menuitem',
                     'label'    => 'vcard_attachments.forwardvcard',
                     'command'  => 'attach-vcard',
                     'class'    => 'icon vcard',
                     'classact' => 'icon vcard active',
                     'innerclass' => 'icon vcard',
-                ),
-                'contactmenu');
+                ],
+                'contactmenu'
+            );
         }
         else {
             if ($rcmail->action == 'show' || $rcmail->action == 'preview') {
-                $this->add_hook('message_load', array($this, 'message_load'));
-                $this->add_hook('message_objects', array($this, 'message_objects'));
-                $this->add_hook('template_object_messagebody', array($this, 'html_output'));
+                $this->add_hook('message_load', [$this, 'message_load']);
+                $this->add_hook('message_objects', [$this, 'message_objects']);
+                $this->add_hook('template_object_messagebody', [$this, 'html_output']);
             }
             else if ($rcmail->action == 'upload') {
-                $this->add_hook('attachment_from_uri', array($this, 'attach_vcard'));
+                $this->add_hook('attachment_from_uri', [$this, 'attach_vcard']);
             }
             else if ($rcmail->action == 'compose' && !$rcmail->output->framed) {
                 $skin_path = $this->local_skin_path();
@@ -52,8 +55,7 @@ class vcard_attachments extends rcube_plugin
                 $this->add_texts('localization', true);
                 $this->include_stylesheet($skin_path . '/style.css');
                 $this->include_script('vcardattach.js');
-                $this->add_button(
-                    array(
+                $this->add_button([
                         'type'     => 'link',
                         'label'    => 'vcard_attachments.vcard',
                         'command'  => 'attach-vcard',
@@ -61,10 +63,11 @@ class vcard_attachments extends rcube_plugin
                         'classact' => $btn_class . ' vcard',
                         'title'    => 'vcard_attachments.attachvcard',
                         'innerclass' => 'inner',
-                    ),
-                    'compose-contacts-toolbar');
+                    ],
+                    'compose-contacts-toolbar'
+                );
 
-                $this->add_hook('message_compose', array($this, 'message_compose'));
+                $this->add_hook('message_compose', [$this, 'message_compose']);
             }
             else if (!$rcmail->output->framed && (!$rcmail->action || $rcmail->action == 'list')) {
                 $skin_path = $this->local_skin_path();
@@ -73,7 +76,7 @@ class vcard_attachments extends rcube_plugin
             }
         }
 
-        $this->register_action('plugin.savevcard', array($this, 'save_vcard'));
+        $this->register_action('plugin.savevcard', [$this, 'save_vcard']);
     }
 
     /**
@@ -129,13 +132,14 @@ class vcard_attachments extends rcube_plugin
                 $vid     = rcube::JQ($part.':'.$idx);
 
                 // add box below message body
-                $p['content'][] = html::p(array('class' => 'vcardattachment aligned-buttons boxinformation'),
-                    html::span(null, rcube::Q($display)) .
-                    html::tag('button', array(
+                $p['content'][] = html::p(['class' => 'vcardattachment aligned-buttons boxinformation'],
+                    html::span(null, rcube::Q($display))
+                    . html::tag('button', [
                             'onclick' => "return plugin_vcard_save_contact('$vid')",
                             'title'   => $this->gettext('addvcardmsg'),
                             'class'   => 'import',
-                        ), rcube::Q($rcmail->gettext('import')))
+                        ], rcube::Q($rcmail->gettext('import'))
+                    )
                 );
             }
 
@@ -155,8 +159,11 @@ class vcard_attachments extends rcube_plugin
      */
     function message_compose($p)
     {
-        if (rcube_utils::get_input_value('_attach_vcard', rcube_utils::INPUT_GET) == '1' && ($uri = rcube_utils::get_input_value('_uri', rcube_utils::INPUT_GET))) {
-            if ($attachment = $this->attach_vcard(array('compose_id' => $p['compose_id'], 'uri' => $uri))) {
+        if (
+            rcube_utils::get_input_value('_attach_vcard', rcube_utils::INPUT_GET) == '1'
+            && ($uri = rcube_utils::get_input_value('_uri', rcube_utils::INPUT_GET))
+        ) {
+            if ($attachment = $this->attach_vcard(['compose_id' => $p['compose_id'], 'uri' => $uri])) {
                 $p['attachments'][] = $attachment;
             };
         }
@@ -195,7 +202,7 @@ class vcard_attachments extends rcube_plugin
         $message = new rcube_message($uid, $mbox);
 
         if ($uid && $mime_id) {
-            list($mime_id, $index) = explode(':', $mime_id);
+            list($mime_id, $index) = rcube_utils::explode(':', $mime_id);
             $part = $message->get_part_content($mime_id, null, true);
         }
 
@@ -220,6 +227,7 @@ class vcard_attachments extends rcube_plugin
 
                 // compare e-mail address
                 $existing = $CONTACTS->search('email', $email, 1, false);
+
                 // compare display name
                 if (!$existing->count && $vcard->displayname) {
                     $existing = $CONTACTS->search('name', $vcard->displayname, 1, false);
@@ -232,7 +240,7 @@ class vcard_attachments extends rcube_plugin
             }
 
             if ($valid) {
-                $plugin = $rcmail->plugins->exec_hook('contact_create', array('record' => $contact, 'source' => null));
+                $plugin = $rcmail->plugins->exec_hook('contact_create', ['record' => $contact, 'source' => null]);
                 $contact = $plugin['record'];
 
                 if (!$plugin['abort'] && $CONTACTS->insert($contact))
@@ -253,9 +261,9 @@ class vcard_attachments extends rcube_plugin
      *
      * @param rcube_message_part Part object
      *
-     * @return boolean True if part is of type vcard
+     * @return bool True if part is of type vcard
      */
-    function is_vcard($part)
+    private static function is_vcard($part)
     {
         return (
             // Content-Type: text/vcard;
@@ -264,10 +272,9 @@ class vcard_attachments extends rcube_plugin
             $part->mimetype == 'text/x-vcard' ||
             // Content-Type: text/directory; profile=vCard;
             ($part->mimetype == 'text/directory' && (
-                ($part->ctype_parameters['profile'] &&
-                    strtolower($part->ctype_parameters['profile']) == 'vcard')
+                    (!empty($part->ctype_parameters['profile']) && strtolower($part->ctype_parameters['profile']) == 'vcard')
             // Content-Type: text/directory; (with filename=*.vcf)
-                    || ($part->filename && preg_match('/\.vcf$/i', $part->filename))
+                    || (!empty($part->filename) && preg_match('/\.vcf$/i', $part->filename))
                 )
             )
         );
@@ -305,13 +312,14 @@ class vcard_attachments extends rcube_plugin
         if (preg_match('|^vcard://(.+)$|', $args['uri'], $m)) {
             list($source, $cid, $email) = explode('-', $m[1]);
 
-            $vcard  = $this->get_contact_vcard($source, $cid, $filename);
-            $params = array(
-                'filename' => $filename,
-                'mimetype' => 'text/vcard',
-            );
+            $vcard = $this->get_contact_vcard($source, $cid, $filename);
 
             if ($vcard) {
+                $params = [
+                    'filename' => $filename,
+                    'mimetype' => 'text/vcard',
+                ];
+
                 $args['attachment'] = rcmail_action_mail_compose::save_attachment($vcard, null, $args['compose_id'], $params);
             }
         }
@@ -336,11 +344,11 @@ class vcard_attachments extends rcube_plugin
                 $vcard->reset();
 
                 foreach ($contact as $key => $values) {
-                    list($field, $section) = explode(':', $key);
+                    list($field, $section) = rcube_utils::explode(':', $key);
                     // avoid unwanted casting of DateTime objects to an array
                     // (same as in rcube_contacts::convert_save_data())
                     if (is_object($values) && is_a($values, 'DateTime')) {
-                        $values = array($values);
+                        $values = [$values];
                     }
 
                     foreach ((array) $values as $value) {
diff --git a/plugins/virtuser_file/virtuser_file.php b/plugins/virtuser_file/virtuser_file.php
index 2d78717a5..9b815acce 100644
--- a/plugins/virtuser_file/virtuser_file.php
+++ b/plugins/virtuser_file/virtuser_file.php
@@ -16,14 +16,17 @@ class virtuser_file extends rcube_plugin
     private $file;
     private $app;
 
+    /**
+     * Plugin initialization
+     */
     function init()
     {
-        $this->app = rcmail::get_instance();
+        $this->app  = rcmail::get_instance();
         $this->file = $this->app->config->get('virtuser_file');
 
         if ($this->file) {
-            $this->add_hook('user2email', array($this, 'user2email'));
-            $this->add_hook('email2user', array($this, 'email2user'));
+            $this->add_hook('user2email', [$this, 'user2email']);
+            $this->add_hook('email2user', [$this, 'email2user']);
         }
     }
 
@@ -33,7 +36,7 @@ class virtuser_file extends rcube_plugin
     function user2email($p)
     {
         $r = $this->findinvirtual('/\s' . preg_quote($p['user'], '/') . '\s*$/');
-        $result = array();
+        $result = [];
 
         for ($i=0; $i<count($r); $i++) {
             $arr = preg_split('/\s+/', $r[$i]);
@@ -41,14 +44,14 @@ class virtuser_file extends rcube_plugin
             if (count($arr) > 0 && strpos($arr[0], '@')) {
                 $result[] = rcube_utils::idn_to_ascii(trim(str_replace('\\@', '@', $arr[0])));
 
-                if ($p['first']) {
+                if (!empty($p['first'])) {
                     $p['email'] = $result[0];
                     break;
                 }
             }
         }
 
-        $p['email'] = empty($result) ? NULL : $result;
+        $p['email'] = empty($result) ? null : $result;
 
         return $p;
     }
@@ -75,28 +78,33 @@ class virtuser_file extends rcube_plugin
     /**
      * Find matches of the given pattern in virtuser file
      *
-     * @param string Regular expression to search for
+     * @param string $pattern Regular expression to search for
+     *
      * @return array Matching entries
      */
     private function findinvirtual($pattern)
     {
-        $result = array();
+        $result  = [];
         $virtual = null;
 
-        if ($this->file)
+        if ($this->file) {
             $virtual = file($this->file);
+        }
 
-        if (empty($virtual))
+        if (empty($virtual)) {
             return $result;
+        }
 
         // check each line for matches
         foreach ($virtual as $line) {
             $line = trim($line);
-            if (empty($line) || $line[0]=='#')
+            if (empty($line) || $line[0] == '#') {
                 continue;
+            }
 
-            if (preg_match($pattern, $line))
+            if (preg_match($pattern, $line)) {
                 $result[] = $line;
+            }
         }
 
         return $result;
diff --git a/plugins/virtuser_query/virtuser_query.php b/plugins/virtuser_query/virtuser_query.php
index 8ebdeb3fc..693b2f993 100644
--- a/plugins/virtuser_query/virtuser_query.php
+++ b/plugins/virtuser_query/virtuser_query.php
@@ -12,7 +12,7 @@
  * The email query could optionally select identity data columns in specified order:
  *    name, organization, reply-to, bcc, signature, html_signature
  *
- * $config['virtuser_query'] = array('email' => '', 'user' => '', 'host' => '', 'alias' => '');
+ * $config['virtuser_query'] = ['email' => '', 'user' => '', 'host' => '', 'alias' => ''];
  *
  * The email query can return more than one record to create more identities.
  * This requires identities_level option to be set to value less than 2.
@@ -38,20 +38,20 @@ class virtuser_query extends rcube_plugin
 
         if (!empty($this->config)) {
             if (is_string($this->config)) {
-                $this->config = array('email' => $this->config);
+                $this->config = ['email' => $this->config];
             }
 
-            if ($this->config['email']) {
-                $this->add_hook('user2email', array($this, 'user2email'));
+            if (!empty($this->config['email'])) {
+                $this->add_hook('user2email', [$this, 'user2email']);
             }
-            if ($this->config['user']) {
-                $this->add_hook('email2user', array($this, 'email2user'));
+            if (!empty($this->config['user'])) {
+                $this->add_hook('email2user', [$this, 'email2user']);
             }
-            if ($this->config['host']) {
-                $this->add_hook('authenticate', array($this, 'user2host'));
+            if (!empty($this->config['host'])) {
+                $this->add_hook('authenticate', [$this, 'user2host']);
             }
-            if ($this->config['alias']) {
-                $this->add_hook('authenticate', array($this, 'alias2user'));
+            if (!empty($this->config['alias'])) {
+                $this->add_hook('authenticate', [$this, 'alias2user']);
             }
         }
     }
@@ -64,26 +64,26 @@ class virtuser_query extends rcube_plugin
         $dbh = $this->get_dbh();
 
         $sql_result = $dbh->query(preg_replace('/%u/', $dbh->escape($p['user']), $this->config['email']));
-        $result     = array();
+        $result     = [];
 
         while ($sql_arr = $dbh->fetch_array($sql_result)) {
             if (strpos($sql_arr[0], '@')) {
-                if ($p['extended'] && count($sql_arr) > 1) {
-                    $result[] = array(
+                if (!empty($p['extended']) && count($sql_arr) > 1) {
+                    $result[] = [
                         'email'          => rcube_utils::idn_to_ascii($sql_arr[0]),
-                        'name'           => (string) $sql_arr[1],
-                        'organization'   => (string) $sql_arr[2],
-                        'reply-to'       => (string) rcube_utils::idn_to_ascii($sql_arr[3]),
-                        'bcc'            => (string) rcube_utils::idn_to_ascii($sql_arr[4]),
-                        'signature'      => (string) $sql_arr[5],
-                        'html_signature' => (int) $sql_arr[6],
-                    );
+                        'name'           => isset($sql_arr[1]) ? $sql_arr[1] : '',
+                        'organization'   => isset($sql_arr[2]) ? $sql_arr[2] : '',
+                        'reply-to'       => isset($sql_arr[3]) ? rcube_utils::idn_to_ascii($sql_arr[3]) : '',
+                        'bcc'            => isset($sql_arr[4]) ? rcube_utils::idn_to_ascii($sql_arr[4]) : '',
+                        'signature'      => isset($sql_arr[5]) ? $sql_arr[5] : '',
+                        'html_signature' => isset($sql_arr[6]) ? intval($sql_arr[6]) : 0,
+                    ];
                 }
                 else {
                     $result[] = $sql_arr[0];
                 }
 
-                if ($p['first']) {
+                if (!empty($p['first'])) {
                     break;
                 }
             }
@@ -161,5 +161,4 @@ class virtuser_query extends rcube_plugin
 
         return $this->db;
     }
-
 }
diff --git a/plugins/zipdownload/config.inc.php.dist b/plugins/zipdownload/config.inc.php.dist
index 28dee7f4b..019cc8de5 100644
--- a/plugins/zipdownload/config.inc.php.dist
+++ b/plugins/zipdownload/config.inc.php.dist
@@ -17,5 +17,3 @@ $config['zipdownload_selection'] = '50MB';
 
 // Charset to use for filenames inside the zip
 $config['zipdownload_charset'] = 'ISO-8859-1';
-
-?>
\ No newline at end of file
diff --git a/plugins/zipdownload/localization/en_US.inc b/plugins/zipdownload/localization/en_US.inc
index a5847fba9..9b77ab0c9 100644
--- a/plugins/zipdownload/localization/en_US.inc
+++ b/plugins/zipdownload/localization/en_US.inc
@@ -14,7 +14,6 @@
  For translation see https://www.transifex.com/projects/p/roundcube-webmail/resource/plugin-zipdownload/
 */
 
-$labels = array();
 $labels['downloadall'] = 'Download all attachments';
 $labels['download'] = 'Download...';
 $labels['downloadmbox'] = 'Mbox format (.zip)';
diff --git a/plugins/zipdownload/tests/Zipdownload.php b/plugins/zipdownload/tests/Zipdownload.php
index 180866591..7e95a1d60 100644
--- a/plugins/zipdownload/tests/Zipdownload.php
+++ b/plugins/zipdownload/tests/Zipdownload.php
@@ -20,4 +20,3 @@ class Zipdownload_Plugin extends PHPUnit\Framework\TestCase
         $this->assertInstanceOf('rcube_plugin', $plugin);
     }
 }
-
diff --git a/plugins/zipdownload/zipdownload.php b/plugins/zipdownload/zipdownload.php
index 5a393939f..fb6b72809 100644
--- a/plugins/zipdownload/zipdownload.php
+++ b/plugins/zipdownload/zipdownload.php
@@ -17,7 +17,7 @@ class zipdownload extends rcube_plugin
     public $task = 'mail';
 
     private $charset       = 'ASCII';
-    private $names         = array();
+    private $names         = [];
     private $default_limit = '50MB';
 
     // RFC4155: mbox date format
@@ -30,11 +30,13 @@ class zipdownload extends rcube_plugin
     {
         // check requirements first
         if (!class_exists('ZipArchive', false)) {
-            rcmail::raise_error(array(
-                'code'    => 520,
-                'file'    => __FILE__,
-                'line'    => __LINE__,
-                'message' => "php_zip extension is required for the zipdownload plugin"), true, false);
+            rcmail::raise_error([
+                    'code'    => 520,
+                    'file'    => __FILE__,
+                    'line'    => __LINE__,
+                    'message' => "php-zip extension is required for the zipdownload plugin"
+                ], true, false
+            );
             return;
         }
 
@@ -45,11 +47,11 @@ class zipdownload extends rcube_plugin
 
         if ($rcmail->config->get('zipdownload_attachments', 1) > -1 && ($rcmail->action == 'show' || $rcmail->action == 'preview')) {
             $this->add_texts('localization');
-            $this->add_hook('template_object_messageattachments', array($this, 'attachment_ziplink'));
+            $this->add_hook('template_object_messageattachments', [$this, 'attachment_ziplink']);
         }
 
-        $this->register_action('plugin.zipdownload.attachments', array($this, 'download_attachments'));
-        $this->register_action('plugin.zipdownload.messages', array($this, 'download_messages'));
+        $this->register_action('plugin.zipdownload.attachments', [$this, 'download_attachments']);
+        $this->register_action('plugin.zipdownload.messages', [$this, 'download_messages']);
 
         if (!$rcmail->action && $rcmail->config->get('zipdownload_selection', $this->default_limit)) {
             $this->add_texts('localization');
@@ -66,20 +68,21 @@ class zipdownload extends rcube_plugin
 
         // only show the link if there is more than the configured number of attachments
         if (substr_count($p['content'], '<li') > $rcmail->config->get('zipdownload_attachments', 1)) {
-            $href = $rcmail->url(array(
-                '_action' => 'plugin.zipdownload.attachments',
-                '_mbox'   => $rcmail->output->env['mailbox'],
-                '_uid'    => $rcmail->output->env['uid'],
-            ), false, false, true);
+            $href = $rcmail->url([
+                    '_action' => 'plugin.zipdownload.attachments',
+                    '_mbox'   => $rcmail->output->get_env('mailbox'),
+                    '_uid'    => $rcmail->output->get_env('uid'),
+                ], false, false, true);
 
-            $link = html::a(array('href' => $href, 'class' => 'button zipdownload'),
+            $link = html::a(
+                ['href' => $href, 'class' => 'button zipdownload'],
                 rcube::Q($this->gettext('downloadall'))
             );
 
             // append link to attachments list, slightly different in some skins
             switch (rcmail::get_instance()->config->get('skin')) {
                 case 'classic':
-                    $p['content'] = str_replace('</ul>', html::tag('li', array('class' => 'zipdownload'), $link) . '</ul>', $p['content']);
+                    $p['content'] = str_replace('</ul>', html::tag('li', ['class' => 'zipdownload'], $link) . '</ul>', $p['content']);
                     break;
 
                 default:
@@ -102,25 +105,30 @@ class zipdownload extends rcube_plugin
         $this->add_label('download');
 
         $rcmail  = rcmail::get_instance();
-        $menu    = array();
-        $ul_attr = array('role' => 'menu', 'aria-labelledby' => 'aria-label-zipdownloadmenu');
+        $menu    = [];
+        $ul_attr = ['role' => 'menu', 'aria-labelledby' => 'aria-label-zipdownloadmenu'];
+
         if ($rcmail->config->get('skin') != 'classic') {
             $ul_attr['class'] = 'toolbarmenu menu';
         }
 
-        foreach (array('eml', 'mbox', 'maildir') as $type) {
-            $menu[] = html::tag('li', null, $rcmail->output->button(array(
+        foreach (['eml', 'mbox', 'maildir'] as $type) {
+            $menu[] = html::tag('li', null, $rcmail->output->button([
                     'command'  => "download-$type",
                     'label'    => "zipdownload.download$type",
                     'class'    => "download $type disabled",
                     'classact' => "download $type active",
                     'type'     => 'link',
-            )));
+                ])
+            );
         }
 
-        $rcmail->output->add_footer(html::div(array('id' => 'zipdownload-menu', 'class' => 'popupmenu', 'aria-hidden' => 'true'),
-            html::tag('h2', array('class' => 'voice', 'id' => 'aria-label-zipdownloadmenu'), "Message Download Options Menu") .
-            html::tag('ul', $ul_attr, implode('', $menu))));
+        $rcmail->output->add_footer(
+            html::div(['id' => 'zipdownload-menu', 'class' => 'popupmenu', 'aria-hidden' => 'true'],
+                html::tag('h2', ['class' => 'voice', 'id' => 'aria-label-zipdownloadmenu'], "Message Download Options Menu")
+                . html::tag('ul', $ul_attr, implode('', $menu))
+            )
+        );
     }
 
     /**
@@ -134,7 +142,7 @@ class zipdownload extends rcube_plugin
         $rcmail->request_security_check(rcube_utils::INPUT_GET);
 
         $tmpfname  = rcube_utils::temp_filename('zipdownload');
-        $tempfiles = array($tmpfname);
+        $tempfiles = [$tmpfname];
         $message   = new rcube_message(rcube_utils::get_input_value('_uid', rcube_utils::INPUT_GET));
 
         // open zip file
@@ -142,8 +150,8 @@ class zipdownload extends rcube_plugin
         $zip->open($tmpfname, ZIPARCHIVE::OVERWRITE);
 
         foreach ($message->attachments as $part) {
-            $pid      = $part->mime_id;
-            $part     = $message->mime_parts[$pid];
+            $pid       = $part->mime_id;
+            $part      = $message->mime_parts[$pid];
             $disp_name = $this->_create_displayname($part);
 
             $tmpfn       = rcube_utils::temp_filename('zipattach');
@@ -193,7 +201,7 @@ class zipdownload extends rcube_plugin
      */
     private function _create_displayname($part)
     {
-        $rcmail    = rcmail::get_instance();
+        $rcmail   = rcmail::get_instance();
         $filename = $part->filename;
 
         if ($filename === null || $filename === '') {
@@ -239,10 +247,10 @@ class zipdownload extends rcube_plugin
         $limit     = $limit !== true ? parse_bytes($limit) : -1;
         $delimiter = $imap->get_hierarchy_delimiter();
         $tmpfname  = rcube_utils::temp_filename('zipdownload');
-        $tempfiles = array($tmpfname);
+        $tempfiles = [$tmpfname];
         $folders   = count($messageset) > 1;
         $timezone  = new DateTimeZone('UTC');
-        $messages  = array();
+        $messages  = [];
         $size      = 0;
 
         // collect messages metadata (and check size limit)
@@ -293,10 +301,10 @@ class zipdownload extends rcube_plugin
                 if ($limit > 0 && $size > $limit) {
                     unlink($tmpfname);
 
-                    $msg = $this->gettext(array(
+                    $msg = $this->gettext([
                             'name' => 'sizelimiterror',
-                            'vars' => array('$size' => rcmail_action::show_bytes($limit))
-                    ));
+                            'vars' => ['$size' => rcmail_action::show_bytes($limit)]
+                    ]);
 
                     $rcmail->output->show_message($msg, 'error');
                     $rcmail->output->send('iframe');
@@ -367,7 +375,7 @@ class zipdownload extends rcube_plugin
     {
         $rcmail = rcmail::get_instance();
 
-        $rcmail->output->download_headers($filename, array('length' => filesize($tmpfname)));
+        $rcmail->output->download_headers($filename, ['length' => filesize($tmpfname)]);
 
         readfile($tmpfname);
     }
@@ -377,7 +385,7 @@ class zipdownload extends rcube_plugin
      */
     private function _convert_filename($str)
     {
-        $str = strtr($str, array(':' => '', '/' => '-'));
+        $str = strtr($str, [':' => '', '/' => '-']);
 
         return rcube_charset::convert($str, RCUBE_CHARSET, $this->charset);
     }
diff --git a/tests/StorageMock.php b/tests/StorageMock.php
index 8edc29401..4fdbf3ee9 100644
--- a/tests/StorageMock.php
+++ b/tests/StorageMock.php
@@ -24,6 +24,8 @@
  */
 class StorageMock
 {
+    public $methodCalls = [];
+
     protected $mocks = [];
 
     public function registerFunction($name, $result = null)
@@ -38,6 +40,7 @@ class StorageMock
         foreach ($this->mocks as $idx => $mock) {
             if ($mock[0] == $name) {
                 $result = $mock[1];
+                $this->methodCalls[] = ['name' => $name, 'args' => $arguments];
                 unset($this->mocks[$idx]);
                 return $result;
             }