Add test on nextRunDate in KeyCheckWorker

[MAILPOET-3271]

tests/integration/Cron/Workers/KeyCheck/KeyCheckWorkerTest.php

@@ -69,6 +69,31 @@ class KeyCheckWorkerTest extends \MailPoetTest {
     expect($result)->false();
   }
 
+  public function testItNextRunIsNextDay(): void {
+    $dateTime = Carbon::now();
+    $wp = Stub::make(new WPFunctions, [
+      'currentTime' => function($format) use ($dateTime) {
+        return $dateTime->getTimestamp();
+      },
+    ]);
+
+    $worker = Stub::make(
+      $this->worker,
+      [
+        'checkKey' => ['code' => Bridge::CHECK_ERROR_UNAVAILABLE],
+        'wp' => $wp,
+      ],
+      $this
+    );
+
+    /** @var Carbon $nextRunDate */
+    $nextRunDate = $worker->getNextRunDate();
+    $secondsToMidnight = $dateTime->diffInSeconds($dateTime->copy()->startOfDay()->addDay());
+
+    // next run should be planned in 6 hours after midnight
+    expect($nextRunDate->diffInSeconds($dateTime))->lessOrEquals(21600 + $secondsToMidnight);
+  }
+
   private function createRunningTask() {
     $task = ScheduledTask::create();
     $task->type = MockKeyCheckWorker::TASK_TYPE;

tests/integration/Cron/Workers/KeyCheck/SendingServiceKeyCheckTest.php

@@ -34,9 +34,11 @@ class SendingServiceKeyCheckTest extends \MailPoetTest {
   }
 
   public function testItRunsEveryHourWhenKeyPendingApproval() {
-    // normally next run is scheduled at a start of next day
+    // normally next run is scheduled at the next day in first six hours
-    expect($this->worker->getNextRunDate()->format('Y-m-d H:i:s'))
+    $nextRun = $this->worker->getNextRunDate();
-      ->equals(Carbon::now()->startOfDay()->addDay()->format('Y-m-d H:i:s'));
+    $nextDay = Carbon::now()->startOfDay()->addDay()->addHours(6);
+    expect($nextRun->format('Y-m-d'))->equals($nextDay->format('Y-m-d'));
+    expect($nextRun)->lessThan($nextDay);
 
     // when pending key approval, next run is scheduled in an hour
     $settings = $this->diContainer->get(SettingsController::class);