Use tenacity for wait_for_pools

Signed-off-by: mulhern <amulhern@redhat.com>

tests/client-dbus/tests/udev/_utils.py

@@ -31,7 +31,13 @@
 import dbus
 import psutil
 import pyudev
-from tenacity import Retrying, retry_if_exception_type, stop_after_delay, wait_fixed
+from tenacity import (
+    Retrying,
+    retry_if_exception_type,
+    stop_after_attempt,
+    stop_after_delay,
+    wait_fixed,
+)
 
 # isort: LOCAL
 from stratisd_client_dbus import (
@@ -535,32 +541,29 @@ def wait_for_pools(self, expected_num, *, name=None):
         :return: list of pool information found
         :rtype: list of (str * MOPool)
         """
-        (count, limit, dbus_err, found_num, known_pools, start_time) = (
-            0,
-            expected_num + 1,
-            None,
-            None,
-            None,
-            time.time(),
-        )
-        while count < limit and not expected_num == found_num:
-            try:
-                known_pools = get_pools(name=name)
-            except dbus.exceptions.DBusException as err:
-                dbus_err = err
-
-            if known_pools is not None:
-                found_num = len(known_pools)
-
-            time.sleep(3)
-            count += 1
-
-        if found_num is None and dbus_err is not None:
+        try:
+            for attempt in Retrying(
+                retry=(retry_if_exception_type(dbus.exceptions.DBusException)),
+                wait=wait_fixed(3),
+                stop=stop_after_attempt(expected_num + 1),
+                reraise=True,
+            ):
+                with attempt:
+                    known_pools = get_pools(name=name)
+                    if len(known_pools) == expected_num:
+                        break
+        except dbus.exceptions.DBusException as err:
             raise RuntimeError(
-                f"After {time.time() - start_time:.2f} seconds, the only "
-                "response is a D-Bus exception"
-            ) from dbus_err
+                "Failed to obtain any information about pools from the D-Bus"
+            ) from err
 
-        self.assertEqual(found_num, expected_num)
+        # Wait for the D-Bus to show more pools than expected. This can occur
+        # especially when the expected number of pools is zero, and stratisd
+        # receives the GetManagedObjects call immediately after it has set up
+        # the D-Bus connection and before object paths for every set up pool
+        # appear on the D-Bus.
+        time.sleep(3)
+        known_pools = get_pools(name=name)
+        self.assertEqual(len(known_pools), expected_num)
 
         return known_pools