diff --git a/tests/FlightTest.php b/tests/FlightTest.php
index f1fbe594..392574bf 100644
--- a/tests/FlightTest.php
+++ b/tests/FlightTest.php
@@ -200,8 +200,6 @@ class FlightTest extends TestCase
 
         $flight = Flight::findByDays([Days::WEDNESDAY, Days::THURSDAY])->first();
         $this->assertNull($flight);
-
-
     }
 
     /**
@@ -236,6 +234,30 @@ class FlightTest extends TestCase
         $this->assertNull($flights);
     }
 
+    /**
+     *
+     */
+    public function testDayOfWeekTests(): void
+    {
+        $mask = 127;
+        $this->assertTrue(Days::in($mask, Days::$isoDayMap[1]));
+        $this->assertTrue(Days::in($mask, Days::$isoDayMap[2]));
+        $this->assertTrue(Days::in($mask, Days::$isoDayMap[3]));
+        $this->assertTrue(Days::in($mask, Days::$isoDayMap[4]));
+        $this->assertTrue(Days::in($mask, Days::$isoDayMap[5]));
+        $this->assertTrue(Days::in($mask, Days::$isoDayMap[6]));
+        $this->assertTrue(Days::in($mask, Days::$isoDayMap[7]));
+
+        $mask = 125;
+        $this->assertTrue(Days::in($mask, Days::$isoDayMap[1]));
+        $this->assertFalse(Days::in($mask, Days::$isoDayMap[2]));
+        $this->assertTrue(Days::in($mask, Days::$isoDayMap[3]));
+        $this->assertTrue(Days::in($mask, Days::$isoDayMap[4]));
+        $this->assertTrue(Days::in($mask, Days::$isoDayMap[5]));
+        $this->assertTrue(Days::in($mask, Days::$isoDayMap[6]));
+        $this->assertTrue(Days::in($mask, Days::$isoDayMap[7]));
+    }
+
     public function testStartEndDate(): void
     {
         $this->user = factory(App\Models\User::class)->create();