diff --git a/lib/Models/ScheduledTaskSubscriber.php b/lib/Models/ScheduledTaskSubscriber.php
index c0a9debb89..a967b22876 100644
--- a/lib/Models/ScheduledTaskSubscriber.php
+++ b/lib/Models/ScheduledTaskSubscriber.php
@@ -21,7 +21,7 @@ class ScheduledTaskSubscriber extends Model {
 
     $task_subscriber->task_id = $data['task_id'];
     $task_subscriber->subscriber_id = $data['subscriber_id'];
-    $task_subscriber->processed = self::STATUS_TO_PROCESS;
+    $task_subscriber->processed = !empty($data['processed']) ? self::STATUS_PROCESSED : self::STATUS_TO_PROCESS;
     $task_subscriber->save();
 
     return $task_subscriber;
diff --git a/tests/unit/Models/ScheduledTaskSubscriberTest.php b/tests/unit/Models/ScheduledTaskSubscriberTest.php
new file mode 100644
index 0000000000..8c9ce081b6
--- /dev/null
+++ b/tests/unit/Models/ScheduledTaskSubscriberTest.php
@@ -0,0 +1,75 @@
+<?php
+namespace MailPoet\Test\Models;
+
+use MailPoet\Models\ScheduledTaskSubscriber;
+
+class ScheduledTaskSubscriberTest extends \MailPoetTest {
+  function _before() {
+    $this->task_id = 123;
+    $this->subscriber_id = 456;
+    $this->task_subscriber = ScheduledTaskSubscriber::createOrUpdate(array(
+      'task_id' => $this->task_id,
+      'subscriber_id' => $this->subscriber_id
+    ));
+  }
+
+  function testItCanBeCreated() {
+    expect($this->task_subscriber->task_id)->equals($this->task_id);
+    expect($this->task_subscriber->subscriber_id)->equals($this->subscriber_id);
+    expect($this->task_subscriber->processed)->equals(ScheduledTaskSubscriber::STATUS_TO_PROCESS);
+  }
+
+  function testItCanBeUpdated() {
+    $task_subscriber = ScheduledTaskSubscriber::createOrUpdate(array(
+      'task_id' => $this->task_id,
+      'subscriber_id' => $this->subscriber_id,
+      'processed' => ScheduledTaskSubscriber::STATUS_PROCESSED
+    ));
+    expect($task_subscriber->processed)->equals(ScheduledTaskSubscriber::STATUS_PROCESSED);
+  }
+
+  function testItCanAddMultipleSubscribers() {
+    ScheduledTaskSubscriber::deleteMany();
+    $subscriber_ids = array(321, 654, 987);
+    ScheduledTaskSubscriber::addSubscribers($this->task_id, $subscriber_ids);
+    $task_subscribers = ScheduledTaskSubscriber::where('task_id', $this->task_id)
+      ->orderByAsc('subscriber_id')
+      ->findMany();
+    expect(count($task_subscribers))->equals(count($subscriber_ids));
+    expect($task_subscribers[0]->subscriber_id)->equals($subscriber_ids[0]);
+    expect($task_subscribers[1]->subscriber_id)->equals($subscriber_ids[1]);
+    expect($task_subscribers[2]->subscriber_id)->equals($subscriber_ids[2]);
+  }
+
+  function testItCanGetToProcessCount() {
+    $count = ScheduledTaskSubscriber::getToProcessCount($this->task_id);
+    expect($count)->equals(1);
+    $this->task_subscriber->processed = ScheduledTaskSubscriber::STATUS_PROCESSED;
+    $this->task_subscriber->save();
+    $count = ScheduledTaskSubscriber::getToProcessCount($this->task_id);
+    expect($count)->equals(0);
+  }
+
+  function testItCanGetProcessedCount() {
+    $count = ScheduledTaskSubscriber::getProcessedCount($this->task_id);
+    expect($count)->equals(0);
+    $this->task_subscriber->processed = ScheduledTaskSubscriber::STATUS_PROCESSED;
+    $this->task_subscriber->save();
+    $count = ScheduledTaskSubscriber::getProcessedCount($this->task_id);
+    expect($count)->equals(1);
+  }
+
+  function testItCanGetTotalCount() {
+    ScheduledTaskSubscriber::createOrUpdate(array(
+      'task_id' => $this->task_id,
+      'subscriber_id' => 555,
+      'processed' => ScheduledTaskSubscriber::STATUS_PROCESSED
+    ));
+    $count = ScheduledTaskSubscriber::getTotalCount($this->task_id);
+    expect($count)->equals(2);
+  }
+
+  function _after() {
+    \ORM::raw_execute('TRUNCATE ' . ScheduledTaskSubscriber::$_table);
+  }
+}
diff --git a/tests/unit/Models/ScheduledTaskTest.php b/tests/unit/Models/ScheduledTaskTest.php
new file mode 100644
index 0000000000..ddc5f71f01
--- /dev/null
+++ b/tests/unit/Models/ScheduledTaskTest.php
@@ -0,0 +1,27 @@
+<?php
+namespace MailPoet\Test\Models;
+
+use MailPoet\Models\ScheduledTask;
+
+class ScheduledTaskTest extends \MailPoetTest {
+  function _before() {
+    $this->task = ScheduledTask::create();
+    $this->task->hydrate(array(
+      'status' => ScheduledTask::STATUS_SCHEDULED
+    ));
+    $this->task->save();
+  }
+
+  function testItCanBeCompleted() {
+    $this->task->complete();
+    expect($this->task->status)->equals(ScheduledTask::STATUS_COMPLETED);
+  }
+
+  function testItSetsDefaultPriority() {
+    expect($this->task->priority)->equals(ScheduledTask::PRIORITY_MEDIUM);
+  }
+
+  function _after() {
+    \ORM::raw_execute('TRUNCATE ' . ScheduledTask::$_table);
+  }
+}
diff --git a/tests/unit/Tasks/Subscribers/BatchIteratorTest.php b/tests/unit/Tasks/Subscribers/BatchIteratorTest.php
new file mode 100644
index 0000000000..a087be70ce
--- /dev/null
+++ b/tests/unit/Tasks/Subscribers/BatchIteratorTest.php
@@ -0,0 +1,56 @@
+<?php
+namespace MailPoet\Test\Tasks\Subscribers;
+
+use MailPoet\Models\ScheduledTaskSubscriber;
+use MailPoet\Tasks\Subscribers\BatchIterator;
+
+class BatchIteratorTest extends \MailPoetTest {
+  function _before() {
+    $this->task_id = 123;
+    $this->batch_size = 2;
+    $this->subscriber_count = 5;
+    for($i = 0; $i < $this->subscriber_count; $i++) {
+      ScheduledTaskSubscriber::createOrUpdate(array(
+        'task_id' => $this->task_id,
+        'subscriber_id' => $i + 1,
+      ));
+    }
+    $this->iterator = new BatchIterator($this->task_id, $this->batch_size);
+  }
+
+  function testItFailsToConstructWithWrongArguments() {
+    try {
+      $iterator = new BatchIterator(0, 0);
+      $this->fail('Exception was not thrown');
+    } catch(\Exception $e) {
+      // No exception handling necessary
+    }
+  }
+
+  function testItConstructs() {
+    $iterator = new BatchIterator(123, 456);
+    expect_that($iterator instanceof BatchIterator);
+  }
+
+  function testItIterates() {
+    $iterations = ceil($this->subscriber_count / $this->batch_size);
+    $i = 0;
+    foreach($this->iterator as $batch) {
+      $i++;
+      if($i < $iterations) {
+        expect(count($batch))->equals($this->batch_size);
+      } else {
+        expect(count($batch))->lessOrEquals($this->batch_size);
+      }
+    }
+    expect($i)->equals($iterations);
+  }
+
+  function testItCanBeCounted() {
+    expect(count($this->iterator))->equals($this->subscriber_count);
+  }
+
+  function _after() {
+    \ORM::raw_execute('TRUNCATE ' . ScheduledTaskSubscriber::$_table);
+  }
+}