fix: Fix failure rate in public API

apps/codecov-api/api/public/v2/test_results/serializers.py

@@ -1,3 +1,4 @@
+from django.db.models import Count, Q
 from rest_framework import serializers
 
 from reports.models import TestInstance
@@ -13,15 +14,33 @@
     outcome = serializers.CharField(label="outcome")
     branch = serializers.CharField(label="branch name")
     repoid = serializers.IntegerField(label="repo id")
-    failure_rate = serializers.FloatField(
-        source="test.failure_rate", read_only=True, label="failure rate"
-    )
+    failure_rate = serializers.SerializerMethodField(label="failure rate")
     commits_where_fail = serializers.ListField(
         source="test.commits_where_fail",
         read_only=True,
         label="commits where test failed",
     )
 
+    def get_failure_rate(self, obj):
+        """Calculate the failure rate for a test.
+        The failure rate is calculated as:
+        number of failed test runs / total number of test runs
+        Returns:
+            float: A value between 0.0 and 1.0 representing the failure rate
+                  0.0 means no failures
+                  1.0 means all runs failed
+        """
+        stats = TestInstance.objects.filter(test=obj.test).aggregate(
+            total=Count("id"),
+            failures=Count("id", filter=Q(outcome=TestInstance.Outcome.FAILURE.value)),
+        )
+
+        total_runs = stats["total"]
+        if total_runs == 0:
+            return 0.0
+
+        return stats["failures"] / total_runs
+
     class Meta:
         model = TestInstance
         read_only_fields = (

apps/codecov-api/api/public/v2/tests/test_test_results_view.py

@@ -53,6 +53,7 @@ def test_list(self):
                     "outcome": self.test_instances[0].outcome,
                     "branch": self.test_instances[0].branch,
                     "repoid": self.test_instances[0].repoid,
+                    "failure_rate": 1.0,
                 },
                 {
                     "id": self.test_instances[1].id,
@@ -64,6 +65,7 @@ def test_list(self):
                     "outcome": self.test_instances[1].outcome,
                     "branch": self.test_instances[1].branch,
                     "repoid": self.test_instances[1].repoid,
+                    "failure_rate": 1.0,
                 },
             ],
             "total_pages": 1,
@@ -95,6 +97,7 @@ def test_list_filters(self):
                     "outcome": self.test_instances[0].outcome,
                     "branch": self.test_instances[0].branch,
                     "repoid": self.test_instances[0].repoid,
+                    "failure_rate": 1.0,
                 },
             ],
             "total_pages": 1,
@@ -125,6 +128,7 @@ def test_retrieve(self, get_repo_permissions):
             "outcome": self.test_instances[0].outcome,
             "branch": self.test_instances[0].branch,
             "repoid": self.test_instances[0].repoid,
+            "failure_rate": 1.0,
         }
 
     @patch("api.shared.permissions.RepositoryArtifactPermissions.has_permission")
@@ -226,4 +230,5 @@ def test_result_with_valid_super_token(
             "outcome": self.test_instances[0].outcome,
             "branch": self.test_instances[0].branch,
             "repoid": self.test_instances[0].repoid,
+            "failure_rate": 1.0,
         }