Don't show sources if their count has not changed (#4176)

* Don't show sources if their count has not changed

* Add explanation for missing sources

catalog/dags/data_refresh/reporting.py

@@ -29,8 +29,10 @@ def report_record_difference(before: dict, after: dict, media_type: str, dag_id:
     breakdown_diff = {k: after.get(k, 0) - before.get(k, 0) for k in all_keys}
     if breakdown_diff:
         breakdown_message = "\n".join(
-            f"`{k}`:{v:+,}" for k, v in breakdown_diff.items()
+            f"`{k}`:{v:+,}" for k, v in breakdown_diff.items() if v != 0
         )
+        if any(v == 0 for v in breakdown_diff.values()):
+            breakdown_message += "\n_Sources not listed had no change in count_"
     else:
         breakdown_message = "Both indices missing? No breakdown to show"
 
@@ -40,8 +42,8 @@ def report_record_difference(before: dict, after: dict, media_type: str, dag_id:
 *Record count difference for `{media_type}`*: {total_before:,} → {total_after:,}
 *Change*: {count_diff:+,} ({percent_diff:+}% Δ)
 *Breakdown of changes*:
+{breakdown_message}
 """
-    message += breakdown_message
     slack.send_message(
         text=message, dag_id=dag_id, username="Data refresh record difference"
     )

catalog/tests/dags/data_refresh/test_reporting.py

@@ -19,7 +19,8 @@
         [
             {"src1": 4, "src2": 21},
             {"src1": 4},
-            ["25 → 4", "-21 (-84.0%", "`src1`:+0", "`src2`:-21"],
+            # Unchanged source count shouldn't show up
+            ["25 → 4", "-21 (-84.0%", "`src2`:-21"],
         ],
         [
             {"src1": 4000, "src2": 20},
@@ -36,6 +37,7 @@
             {},
             ["20 → 0", "-20 (-100.0%", "`src1`:-10", "`src2`:-10"],
         ],
+        [{"src1": 4}, {"src1": 4}, ["Sources not listed had no change in count"]],
         [{}, {}, ["Both indices missing? No breakdown to show"]],
     ],
 )