fix(metrics): mri namespace bug (#72989)

src/sentry/sentry_metrics/extraction_rules.py

@@ -47,7 +47,7 @@ class MetricsExtractionRule:
     def generate_mri(self, use_case: str = "custom"):
         """Generate the Metric Resource Identifier (MRI) associated with the extraction rule."""
         use_case_id = string_to_use_case_id(use_case)
-        return f"{self.type}:{use_case_id}/{self.span_attribute}@{self.unit}"
+        return f"{self.type}:{use_case_id.value}/{self.span_attribute}@{self.unit}"
 
     def __hash__(self):
         return hash(self.generate_mri())

tests/sentry/sentry_metrics/test_extraction_rules.py

@@ -30,3 +30,9 @@ def test_serialization():
 
     serde_state = MetricsExtractionRuleState.from_json(json_payload)
     assert state == serde_state
+
+
+def test_generate_mri():
+    rule = MetricsExtractionRule("count_clicks", "c", "none", {"tag_1", "tag_2"}, [])
+    mri = rule.generate_mri()
+    assert mri == "c:custom/count_clicks@none"