Fix 500 in sleep pattern (#487)

reports/graphs/sleep_pattern.py

@@ -26,7 +26,9 @@ def sleep_pattern(sleeps):
     last_end_time = None
     adjustment = None
 
-    days = _init_days(sleeps.first().start, sleeps.last().end)
+    first_day = timezone.localtime(sleeps.first().start)
+    last_day = timezone.localtime(sleeps.last().end)
+    days = _init_days(first_day, last_day)
 
     for sleep in sleeps:
         start_time = timezone.localtime(sleep.start)

reports/tests/graphs/tests_sleep_pattern.py

@@ -0,0 +1,31 @@
+# -*- coding: utf-8 -*-
+import datetime as dt
+
+from django.test import TestCase
+from django.utils import timezone
+
+from core import models
+from reports.graphs import sleep_pattern
+
+
+class SleepPatternTestCase(TestCase):
+    def setUp(self):
+        self.original_tz = timezone.get_current_timezone()
+        self.tz = dt.timezone(dt.timedelta(days=-1, hours=1))
+        timezone.activate(self.tz)
+
+    def tearDown(self):
+        timezone.activate(self.original_tz)
+
+    def test_sleep_pattern(self):
+
+        c = models.Child(birth_date=dt.datetime.now())
+        c.save()
+
+        models.Sleep.objects.create(
+            child=c,
+            start=dt.datetime(2000, 1, 1, 0, 0, tzinfo=timezone.utc),
+            end=dt.datetime(2000, 1, 1, 0, 1, tzinfo=timezone.utc),
+        )
+
+        sleep_pattern(models.Sleep.objects.order_by("start"))