Compute hotness even if previous week is 0 (#24246)

Author: diox

src/olympia/addons/tasks.py

@@ -409,13 +409,13 @@ def update_addon_hotness(averages):
             continue
 
         this_week = average['avg_this_week']
-        previous_week = average['avg_previous_week']
+        previous_week = max(average['avg_previous_week'], 1)
         threshold = (
             MINIMUM_ADU_FOR_HOTNESS_THEME
             if addon.type == amo.ADDON_STATICTHEME
             else MINIMUM_ADU_FOR_HOTNESS_NONTHEME
         )
-        if this_week >= threshold and previous_week > 1:
+        if this_week >= threshold:
             hotness = (this_week - previous_week) / float(previous_week)
         else:
             hotness = 0

src/olympia/addons/tests/test_cron.py

@@ -159,6 +159,7 @@ def setUp(self):
         self.awaiting_review = addon_factory(status=amo.STATUS_NOMINATED)
         self.deleted_extension = addon_factory()
         self.deleted_extension.delete()
+        self.previously_unknown_extension = addon_factory()
 
         self.frozen_extension = addon_factory()
         FrozenAddon.objects.create(addon=self.frozen_extension)
@@ -209,6 +210,10 @@ def test_basic(self, get_averages_mock, flag_high_hotness_mock):
                 'avg_this_week': 1040,
                 'avg_previous_week': 1000,
             },
+            self.previously_unknown_extension.guid: {
+                'avg_this_week': 4815,
+                'avg_previous_week': 0,
+            },
         }
 
         cron.update_addon_hotness()
@@ -231,6 +236,9 @@ def test_basic(self, get_averages_mock, flag_high_hotness_mock):
         assert self.awaiting_review.reload().hotness == 0.049687154950312847
         assert self.deleted_extension.reload().hotness == 0.04
 
+        # Previously unknown (nothing last week), we still compute hotness.
+        assert self.previously_unknown_extension.reload().hotness == 4814.0
+
         # Exclude frozen add-ons too.
         assert self.frozen_extension.reload().hotness == 0
         get_averages_mock.assert_called_once_with(