Fix RatingMateriTest get material

app/tests.py

@@ -1991,8 +1991,8 @@ class RatingMateriTest(TestCase):
         Materi(title="Materi Dua", author="Author", uploader=self.contributor,
                publisher="Publisher", descriptions="Deskripsi Materi Dua",
                status="APPROVE", cover=self.cover, content=self.content).save()
-        self.materi1 = Materi.objects.all()[0]
-        self.materi2 = Materi.objects.all()[1]
+        self.materi1 = Materi.objects.filter(title='Materi 1').get()
+        self.materi2 = Materi.objects.filter(title='Materi Dua').get()
         self.url_rate = '/materi/rate/'
         self.url_materi = '/materi/{}/'.format(self.materi1.id)