Don't flag add-ons for growth threshold if hotness is negative (#23031)

* Don't flag add-ons for growth threshold if hotness is negative

src/olympia/addons/tasks.py

@@ -540,8 +540,6 @@ def flag_high_hotness_according_to_review_tier():
     base_qs = UsageTier.get_base_addons()
     hotness_per_tier_filters = Q()
     for usage_tier in usage_tiers:
-        # Note: get_growth_threshold_q_object can return an empty Q() object
-        # if the average hotness for that tier is exactly 0.
         hotness_per_tier_filters |= usage_tier.get_growth_threshold_q_object()
     if not hotness_per_tier_filters:
         return

src/olympia/addons/tests/test_tasks.py

@@ -451,13 +451,15 @@ def test_flag_high_hotness_according_to_review_tier_threshold_check_negative():
         upper_adu_threshold=1000,
         growth_threshold_before_flagging=10,
     )
-    # Average hotness should be negative, -0.1.
+    # Average hotness should be negative, -0.2.
     # growth_threshold_before_flagging for that tier is 10 so we should flag
-    # add-ons with hotness above 0
+    # add-ons with hotness above -0.1, but we explicitly only flag positive
+    # growth add-ons, so only the last one should be flagged.
 
-    addon_factory(average_daily_users=251, hotness=-0.1)
-    addon_factory(average_daily_users=251, hotness=-0.2)
-    addon = addon_factory(average_daily_users=251, hotness=0.0)
+    addon_factory(average_daily_users=251, hotness=-0.05)
+    addon_factory(average_daily_users=251, hotness=-0.85)
+    addon_factory(average_daily_users=251, hotness=0.0)
+    addon = addon_factory(average_daily_users=251, hotness=0.1)
     File.objects.update(is_signed=True)
 
     flag_high_hotness_according_to_review_tier()

src/olympia/reviewers/models.py

@@ -832,28 +832,26 @@ def average_growth(self):
             self.get_base_addons()
             .filter(**self.get_tier_boundaries())
             .aggregate(Avg('hotness', default=0))
-            .get('hotness__avg')
+            .get('hotness__avg', 0)
         )
 
     def get_growth_threshold(self):
-        """Return the growth threshold for that tier, or None.
+        """Return the growth threshold for that tier.
 
         The value is computed from the average growth (hotness) of add-ons in
         that tier plus the growth_threshold_before_flagging converted to
-        decimal."""
-        return self.average_growth + self.growth_threshold_before_flagging / 100
+        decimal.
+
+        It has a floor of 0."""
+        return max(0, self.average_growth + self.growth_threshold_before_flagging / 100)
 
     def get_growth_threshold_q_object(self):
         """Return Q object containing filters to apply to find add-ons over the
         computed growth threshold for that tier."""
-        hotness_ceiling_before_flagging = self.get_growth_threshold()
-        if hotness_ceiling_before_flagging is not None:
-            return Q(
-                hotness__gt=hotness_ceiling_before_flagging,
-                **self.get_tier_boundaries(),
-            )
-        else:
-            return Q()
+        return Q(
+            hotness__gt=self.get_growth_threshold(),
+            **self.get_tier_boundaries(),
+        )
 
 
 class NeedsHumanReview(ModelBase):

src/olympia/reviewers/tests/test_models.py

@@ -1919,6 +1919,16 @@ def test_get_growth_threshold(self):
         del self.tier.average_growth
         assert round(self.tier.get_growth_threshold(), ndigits=2) == 0.77
 
+    def test_get_growth_threshold_zero_floor_instead_of_negative(self):
+        addon_factory(hotness=-0.4, average_daily_users=100)
+        addon_factory(hotness=-0.4, average_daily_users=999)
+        assert round(self.tier.get_growth_threshold(), ndigits=2) == 0.1
+
+        addon_factory(hotness=-0.9, average_daily_users=999)
+        addon_factory(hotness=-0.9, average_daily_users=999)
+        del self.tier.average_growth
+        assert round(self.tier.get_growth_threshold(), ndigits=2) == 0  # Not -0.15
+
     def test_get_growth_threshold_q_object(self):
         addon_factory(hotness=0.01, average_daily_users=100)
         addon_factory(hotness=0.01, average_daily_users=999)
@@ -1928,3 +1938,19 @@ def test_get_growth_threshold_q_object(self):
             list(Addon.objects.filter(self.tier.get_growth_threshold_q_object()))
             == expected
         )
+
+    def test_get_growth_threshold_q_object_hotness_needs_to_be_higher_than(self):
+        addon_factory(hotness=0.5, average_daily_users=999)
+        expected = [addon_factory(hotness=0.501, average_daily_users=999)]
+
+        # Override computed average growth to force the growth threshold to
+        # 0.5 (0.0 + 50/100)
+        self.tier.average_growth = 0.0
+        assert self.tier.get_growth_threshold() == 0.5
+
+        # We filter on hotness_gt in get_growth_threshold_q_object() so the
+        # first add-on shouldn't be returned, only the second one.
+        assert (
+            list(Addon.objects.filter(self.tier.get_growth_threshold_q_object()))
+            == expected
+        )