diff --git a/inc/spbc-settings.php b/inc/spbc-settings.php
index f14ed9f78..2238d9a48 100644
--- a/inc/spbc-settings.php
+++ b/inc/spbc-settings.php
@@ -2921,7 +2921,7 @@ function spbc_scanner_oscron_count_found()
  */
 function spbc_scanner_oscron_get_scanned()
 {
-    return OSCronModel::getTasksFromStorage();
+    return OSCronModel::getTasksFromStorageAsArray();
 }
 
 /**
diff --git a/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronController.php b/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronController.php
index f49e49837..d22344ba2 100644
--- a/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronController.php
+++ b/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronController.php
@@ -16,7 +16,7 @@ private static function updateTask($uid, $status)
         $line_to_change->setStatus($status);
         $result = OSCronModel::updateTaskById($uid, $line_to_change);
         if (false === $result) {
-            return $result;
+            return false;
         }
         return OSCronModel::rewriteCronTabFile();
     }
@@ -31,7 +31,7 @@ public static function approveTask($uid)
     }
     /**
      * @param $uid
-     * @return false|int
+     * @return bool
      * @throws \Exception
      */
     public static function disableTask($uid)
diff --git a/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronLocale.php b/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronLocale.php
new file mode 100644
index 000000000..eda6cf230
--- /dev/null
+++ b/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronLocale.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace CleantalkSP\SpbctWP\Scanner\OSCron;
+
+
+use CleantalkSP\Templates\Singleton;
+
+class OSCronLocale
+{
+
+    use Singleton;
+    public $task_status_approved;
+    public $task_status_disabled;
+    public $task_status_danger;
+    public $no_windows_support;
+    public $no_difference;
+    public $error_write_cron_storage;
+    public $error_write_cron_env;
+    public $error_load_cron_storage;
+    public $error_load_cron_env;
+    public $error_invalid_arg;
+    public $error_missing_property;
+    public $error_load_tasks_storage;
+    public $error_invalid_cron_expression;
+
+    public function init()
+    {
+        $this->task_status_approved = __('Approved', 'security-malware-firewall');
+        $this->task_status_disabled = __('Disabled', 'security-malware-firewall');
+        $this->task_status_danger = __('Danger', 'security-malware-firewall');
+        $this->no_windows_support = __('Windows OS cron handling is not supported.', 'security-malware-firewall');
+        $this->no_difference = __('No difference found since last check.', 'security-malware-firewall');
+        $this->error_write_cron_storage = __('Cannot write cron to storage', 'security-malware-firewall');
+        $this->error_write_cron_env = __('Cannot write cron to environment', 'security-malware-firewall');
+        $this->error_load_cron_storage = __('Cannot load cron content from storage', 'security-malware-firewall');
+        $this->error_load_cron_env = __('No crontab file found in the server environment.', 'security-malware-firewall');
+        $this->error_load_tasks_storage = __('Cannot load tasks from storage', 'security-malware-firewall');
+        $this->error_invalid_arg = __('invalid argument', 'security-malware-firewall');
+        $this->error_missing_property = __('property is no set', 'security-malware-firewall');
+        $this->error_invalid_cron_expression = __('Invalid cron expression', 'security-malware-firewall');
+        //$this->var = __('', 'security-malware-firewall');
+    }
+}
diff --git a/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronModel.php b/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronModel.php
index b36b2dc03..9534ab660 100644
--- a/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronModel.php
+++ b/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronModel.php
@@ -14,26 +14,35 @@ class OSCronModel
     public static function run()
     {
         try {
+            if (static::isWindows()) {
+                throw new \Exception(OSCronLocale::getInstance()->no_windows_support);
+            }
+
             $new_cron_file = static::getEnvCrontab();
 
-            if (static::loadCrontabFile() === $new_cron_file) {
-                throw new \Exception(__('No difference found since last check.', 'security-malware-firewall'));
+            if (static::loadCronFileFromStorage() === $new_cron_file) {
+                throw new \Exception(OSCronLocale::getInstance()->no_difference);
             }
-            static::saveCrontabFile($new_cron_file);
+            static::saveCronFileToStorage($new_cron_file);
             $tasks = static::parseTasks($new_cron_file);
             static::saveTasksToStorage($tasks);
         } catch (\Exception $error) {
-            return (string)$error;
+            return $error->getMessage();
         }
         return true;
     }
 
+    public static function isWindows()
+    {
+        return strtoupper(substr(PHP_OS, 0, 3)) === 'WIN';
+    }
+
     /**
      * @param $cron_file
      * @return OSCronTask[]
      * @throws \Exception
      */
-    private static function parseTasks($cron_file)
+    public static function parseTasks($cron_file)
     {
         $result = explode("\n", $cron_file);
 
@@ -72,34 +81,45 @@ public static function saveTasksToStorage($tasks)
     }
 
     /**
-     * @return OSCronTask[]|array
+     * @return OSCronTask[]
      */
-    public static function getTasksFromStorage($as_array = true)
+    public static function getTasksFromStorage()
     {
-        $tasks = get_option('spbc_oscron_result', []);
+        $tasks = get_option(static::$tasks_storage_name, []);
 
         if (is_null($tasks) || false === $tasks) {
             return array();
         }
 
-        if ($as_array) {
-            $result_array = array();
-            foreach ($tasks as $task) {
+        return $tasks;
+    }
+
+    /**
+     * @return array
+     */
+    public static function getTasksFromStorageAsArray()
+    {
+        global $spbc;
+        $tasks = static::getTasksFromStorage();
+        $result_array = array();
+        foreach ($tasks as $task) {
+            if ($task instanceof OSCronTask) {
                 $result_array[] = $task->getArray();
+            } else {
+                $spbc->error_add('', OSCronLocale::getInstance()->error_load_cron_storage);
             }
-            return $result_array;
         }
-
-        return $tasks;
+        return $result_array;
     }
 
     /**
      * @param string $uid
      * @return OSCronTask|false
+     * @throws \Exception
      */
     public static function getTaskById($uid)
     {
-        $tasks = static::getTasksFromStorage(false);
+        $tasks = static::getTasksFromStorage();
         foreach ($tasks as $task) {
             if ($task->id === $uid) {
                 return $task;
@@ -117,7 +137,7 @@ public static function getTaskById($uid)
     public static function updateTaskById($uid, $new_task)
     {
         $new_task->validate();
-        $tasks = static::getTasksFromStorage(false);
+        $tasks = static::getTasksFromStorage();
         foreach ($tasks as $key => $task) {
             if ($task->id === $uid) {
                 $tasks[$key] = $new_task;
@@ -134,8 +154,8 @@ public static function updateTaskById($uid, $new_task)
      */
     public static function rewriteCronTabFile()
     {
-        $tasks = static::getTasksFromStorage(false);
-        $new_cron_file = static::loadCrontabFile();
+        $tasks = static::getTasksFromStorage();
+        $new_cron_file = static::loadCronFileFromStorage();
         foreach ($tasks as $task) {
             $the_word = $task->repeats . ' ' . $task->command;
             if ($task->status === 'disabled') {
@@ -145,8 +165,14 @@ public static function rewriteCronTabFile()
                 $new_cron_file = str_replace(static::$spbc_marker, '', $new_cron_file);
             }
         }
-        static::saveCrontabFile($new_cron_file);
+        static::saveCronFileToStorage($new_cron_file);
+        if ($new_cron_file !== static::loadCronFileFromStorage()) {
+            throw new \Exception(OSCronLocale::getInstance()->error_write_cron_storage);
+        }
         static::saveEnvCronTab($new_cron_file);
+        if ($new_cron_file !== static::getEnvCrontab()) {
+            throw new \Exception(OSCronLocale::getInstance()->error_write_cron_env);
+        }
         return true;
     }
 
@@ -154,7 +180,7 @@ public static function rewriteCronTabFile()
      * @param $cron_file
      * @return void
      */
-    public static function saveCrontabFile($cron_file)
+    public static function saveCronFileToStorage($cron_file)
     {
         update_option(static::$file_storage_name, @base64_encode($cron_file));
     }
@@ -163,16 +189,16 @@ public static function saveCrontabFile($cron_file)
      * @return string
      * @throws \Exception
      */
-    public static function loadCrontabFile()
+    public static function loadCronFileFromStorage()
     {
         $result = get_option(static::$file_storage_name);
-        if ($result) {
+        if (false !== $result) {
             $result = @base64_decode($result);
-            if ($result) {
+            if (false !== $result) {
                 return $result;
             }
         }
-        throw new \Exception(__('Cannot load crontab file from storage', 'security-malware-firewall'));
+        throw new \Exception(OSCronLocale::getInstance()->error_load_cron_storage);
     }
 
     /**
@@ -190,7 +216,7 @@ private static function getEnvCrontab()
 //5 * * * * bash
 //#not a valid string';
         if (empty($cron_file)) {
-            throw new \Exception(__('No crontab file found in the server environment.', 'security-malware-firewall'));
+            throw new \Exception(OSCronLocale::getInstance()->error_load_cron_env);
         }
         return $cron_file;
     }
diff --git a/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronTask.php b/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronTask.php
index 7d71f3855..9b4821f5d 100644
--- a/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronTask.php
+++ b/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronTask.php
@@ -50,7 +50,7 @@ private function setID()
     public function setStatus($status)
     {
         if (!is_string($status) || !in_array($status, $this->statuses_list)) {
-            throw new \Exception(__CLASS__ . '::' . __FUNCTION__ . 'invalid arg');
+            throw new \Exception(__CLASS__ . '::' . __FUNCTION__ . ' ' . OSCronLocale::getInstance()->error_missing_property);
         }
 
         $this->status = $status;
@@ -65,7 +65,7 @@ public function setStatus($status)
     public function setCommand($command)
     {
         if (!is_string($command)) {
-            throw new \Exception(__CLASS__ . '::' . __FUNCTION__ . 'invalid arg');
+            throw new \Exception(__CLASS__ . '::' . __FUNCTION__ . ' ' . OSCronLocale::getInstance()->error_missing_property);
         }
         $this->command = $command;
         return $this;
@@ -79,7 +79,7 @@ public function setCommand($command)
     public function setRepeatsPattern($repeats)
     {
         if (!is_string($repeats)) {
-            throw new \Exception(__CLASS__ . '::' . __FUNCTION__ . 'invalid arg');
+            throw new \Exception(__CLASS__ . '::' . __FUNCTION__ . ' ' . OSCronLocale::getInstance()->error_missing_property);
         }
         $this->repeats = $repeats;
         return $this;
@@ -93,7 +93,7 @@ public function setRepeatsPattern($repeats)
     public function setLineNumber($line_number)
     {
         if (!is_int($line_number)) {
-            throw new \Exception(__CLASS__ . '::' . __FUNCTION__ . 'invalid arg');
+            throw new \Exception(__CLASS__ . '::' . __FUNCTION__ . ' ' . OSCronLocale::getInstance()->error_missing_property);
         }
         $this->line_number = $line_number;
         return $this;
@@ -107,7 +107,7 @@ public function validate()
     {
         foreach (get_object_vars($this) as $property => $value) {
             if (is_null($value)) {
-                throw new \Exception(__CLASS__ . '::' . __FUNCTION__ . ' - ' . $property . ' is not set');
+                throw new \Exception(__CLASS__ . '::' . __FUNCTION__ . ' - ' . $property . ' ' . OSCronLocale::getInstance()->error_missing_property);
             }
         }
         return $this;
diff --git a/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronView.php b/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronView.php
index a6565ca31..2f3d1a070 100644
--- a/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronView.php
+++ b/lib/CleantalkSP/SpbctWP/Scanner/OSCron/OSCronView.php
@@ -39,7 +39,7 @@ public static function prepareTableData($table)
     }
 
     /**
-     * Convert cron time to human readable.
+     * Convert cron time to a human-readable string.
      * @param $time
      * @return string
      */
@@ -48,7 +48,7 @@ private static function timePatternToHumanReadable($time)
         $cronParts = explode(' ', $time);
 
         if (count($cronParts) !== 5) {
-            return __('Invalid cron expression', 'security-malware-firewall');
+            return OSCronLocale::getInstance()->error_invalid_cron_expression;
         }
 
         list($minute, $hour, $dayOfMonth, $month, $dayOfWeek) = $cronParts;
diff --git a/tests/Scanner/TestOSCron.php b/tests/Scanner/TestOSCron.php
new file mode 100644
index 000000000..92c8e37f5
--- /dev/null
+++ b/tests/Scanner/TestOSCron.php
@@ -0,0 +1,181 @@
+<?php
+
+use CleantalkSP\SpbctWP\Scanner\OSCron\OSCronLocale;
+use CleantalkSP\SpbctWP\Scanner\OSCron\OSCronModel;
+use CleantalkSP\SpbctWP\Scanner\OSCron\OSCronTask;
+
+class TestOSCron extends PHPUnit\Framework\TestCase
+{
+
+    private $test_cron_content;
+
+    public function setUp()
+    {
+        $this->test_cron_content = "1 * * * * echo\n\n\n5 * * * * bash\n#not a valid string";
+    }
+
+    public function testTasksSaveLoad() {
+        $tasks = OSCronModel::parseTasks($this->test_cron_content);
+        OSCronModel::saveTasksToStorage($tasks);
+        $saved_tasks = OSCronModel::getTasksFromStorage(false);
+        $this->assertEquals($tasks, $saved_tasks);
+    }
+
+    public function testContentSaveLoad() {
+        OSCronModel::saveCronFileToStorage($this->test_cron_content);
+        $this->assertEquals($this->test_cron_content, OSCronModel::loadCronFileFromStorage());
+    }
+
+    public function testNoDifference()
+    {
+        OSCronModel::saveCronFileToStorage($this->test_cron_content);
+        $this->expectException(\Exception::class);
+        if (OSCronModel::loadCronFileFromStorage() === $this->test_cron_content) {
+            throw new \Exception(__('No difference found since last check.', 'security-malware-firewall'));
+        }
+    }
+
+    public function testParseTasks()
+    {
+        $tasks = OSCronModel::parseTasks($this->test_cron_content);
+        $this->assertIsArray($tasks);
+        foreach ($tasks as $task) {
+            $this->assertInstanceOf('CleantalkSP\SpbctWP\Scanner\OSCron\OSCronTask', $task);
+        }
+    }
+
+    public function testValidateValidTasks()
+    {
+       $task = new OSCronTask();
+       $task->setCommand('echo')
+          ->setStatus('found')
+          ->setLineNumber(1)
+          ->setRepeatsPattern('1 * * * *')
+          ->validate();
+       $this->assertInstanceof('CleantalkSP\SpbctWP\Scanner\OSCron\OSCronTask', $task);
+
+        $task = new OSCronTask();
+        $task->setCommand('echo')
+            ->setStatus('approved')
+            ->setLineNumber(1211)
+            ->setRepeatsPattern('9 * * * *')
+            ->validate();
+        $this->assertInstanceof('CleantalkSP\SpbctWP\Scanner\OSCron\OSCronTask', $task);
+
+        $task = new OSCronTask();
+        $task->setCommand('echo')
+            ->setStatus('disabled')
+            ->setLineNumber(221)
+            ->setRepeatsPattern('10 * * * *')
+            ->validate();
+        $this->assertInstanceof('CleantalkSP\SpbctWP\Scanner\OSCron\OSCronTask', $task);
+    }
+
+    public function testValidateInValidTasks()
+    {
+        $task = new OSCronTask();
+        $this->expectException(\Exception::class);
+        $task->setCommand('echo')
+            ->setStatus('invalidststus')
+            ->setLineNumber(1)
+            ->setRepeatsPattern('1 * * * *')
+            ->validate();
+
+        $task = new OSCronTask();
+        $this->expectException(\Exception::class);
+        $task->setCommand(7)
+            ->setStatus('approved')
+            ->setLineNumber(1)
+            ->setRepeatsPattern('1 * * * *')
+            ->validate();
+
+        $task = new OSCronTask();
+        $this->expectException(\Exception::class);
+        $task->setCommand('echo')
+            ->setStatus('approved')
+            ->setLineNumber(array())
+            ->setRepeatsPattern('1 * * * *')
+            ->validate();
+
+        $task = new OSCronTask();
+        $this->expectException(\Exception::class);
+        $task->setCommand('echo')
+            ->setStatus('approved')
+            ->setLineNumber(2212)
+            ->setRepeatsPattern(array())
+            ->validate();
+    }
+
+    public function testUpdateTaskFail()
+    {
+        $task = new OSCronTask();
+        $task->setCommand('echo')
+            ->setStatus('approved')
+            ->setLineNumber(2212)
+            ->setRepeatsPattern('1 * * * *')
+            ->validate();
+        OSCronModel::saveTasksToStorage(array($task));
+        //wrong uid
+        $this->assertFalse(OSCronModel::updateTaskById('123', $task));
+    }
+
+    public function testUpdateTaskOK()
+    {
+        $task = new OSCronTask();
+        $task->setCommand('echo')
+            ->setStatus('approved')
+            ->setLineNumber(2212)
+            ->setRepeatsPattern('1 * * * *')
+            ->validate();
+        OSCronModel::saveTasksToStorage(array($task));
+        $this->assertIsInt(OSCronModel::updateTaskById($task->id, $task));
+    }
+
+//    public function testApprove()
+//    {
+//        $task = new OSCronTask();
+//        $task->setCommand('echo')
+//            ->setStatus('found')
+//            ->setLineNumber(2212)
+//            ->setRepeatsPattern('1 * * * *')
+//            ->validate();
+//        OSCronModel::saveTasksToStorage(array($task));
+//        $this->assertTrue(OSCronController::approveTask($task->id));
+//    }
+//
+//    public function testDisable()
+//    {
+//        $task = new OSCronTask();
+//        $task->setCommand('echo')
+//            ->setStatus('found')
+//            ->setLineNumber(2212)
+//            ->setRepeatsPattern('1 * * * *')
+//            ->validate();
+//        OSCronModel::saveTasksToStorage(array($task));
+//        $this->assertTrue(OSCronController::disableTask($task->id));
+//    }
+
+        public function testisWindows()
+        {
+            $this->assertTrue(OSCronModel::isWindows());
+        }
+
+        public function testRun()
+        {
+            $result = OSCronModel::run();
+            if (OSCronModel::isWindows()) {
+                $this->assertIsString($result);
+                $this->assertStringContainsString('Windows', $result);
+            } else {
+                if (true !== $result) {
+                    $this->assertIsString($result);
+                }
+            }
+        }
+
+        public function testLocale()
+        {
+            $this->assertIsString(OSCronLocale::getInstance()->error_invalid_cron_expression);
+        }
+
+}