Diagnose stalled TLSRPT delivery runs

contrib/testing/smtp-tlsrpt-delivery-check.py

@@ -196,6 +196,14 @@ def request_worker() -> None:
         raise SMTP29Error(f"worker request failed: {output}")
 
 
+def scheduler_state() -> object:
+    output = testtool("scheduler-list")
+    try:
+        return json.loads(output)
+    except json.JSONDecodeError:
+        return output
+
+
 def wait_until(function, description: str):
     deadline = time.monotonic() + TIMEOUT
     last = None
@@ -500,12 +508,23 @@ def perform_test() -> None:
         record(event(yesterday, delivery_domain, policy))
         record(event(yesterday, delivery_domain, policy, success=False))
         prepare(today, now, signing_domain)
+        initial_delivery = matching_delivery(delivery_domain)
+        if not initial_delivery:
+            raise SMTP29Error(
+                "prepared TLSRPT delivery is not pending: "
+                f"{next_delivery(int(time.time()) + 172800)!r}")
         request_worker()
 
-        mail_raw = wait_until(
-            lambda: captured_report(smtp_capture, delivery_domain),
-            "TLSRPT mail delivery",
-        )
+        try:
+            mail_raw = wait_until(
+                lambda: captured_report(smtp_capture, delivery_domain),
+                "TLSRPT mail delivery",
+            )
+        except SMTP29Error as error:
+            raise SMTP29Error(
+                f"{error}; pending="
+                f"{next_delivery(int(time.time()) + 172800)!r}; "
+                f"scheduler={scheduler_state()!r}") from error
         https_raw = wait_until(
             lambda: (
                 https_capture.snapshot()[0]
@@ -656,6 +675,10 @@ def perform_test() -> None:
                 discard_delivery(value, "interrupted SMTP-29 test fixture")
             except Exception:
                 pass
+        try:
+            purge_stale_fixture_deliveries()
+        except Exception:
+            pass
         if configuration_changed:
             try:
                 replace_configuration("smtp", original_smtp)