Improve logging from isctest.run.retry_with_timeout

Allow use of exception (and by extension, assert statements) in the
called function in order to extract essential debug information about
the type of failure that was encountered.

In case the called function fails to succeed on the last retry and
raised an exception, log it as error and set it as the assert message to
propagate it through the pytest framework.

(cherry picked from commit 620c884133)

bin/tests/system/isctest/kasp.py

@@ -643,7 +643,9 @@ def check_keys(zone, keys, expected):
     def _verify_keys():
         # check number of keys matches expected.
         if len(keys) != len(expected):
-            return False
+            assert (
+                False
+            ), f"check_keys(): mismatched number of keys, expected {len(expected)}, got {len(keys)}"
 
         if len(keys) == 0:
             return True
@@ -662,7 +664,7 @@ def check_keys(zone, keys, expected):
                         expected[i].key = key
                 i += 1
             if not found:
-                return False
+                assert False, f"check_keys(): key {key} not found"
 
         return True
 

bin/tests/system/isctest/run.py

@@ -127,12 +127,22 @@ def perl(script: str, args: Optional[List[str]] = None) -> None:
 
 def retry_with_timeout(func, timeout, delay=1, msg=None):
     start_time = time.time()
+    exc_msg = None
     while time.time() < start_time + timeout:
-        if func():
-            return
+        exc_msg = None
+        try:
+            if func():
+                return
+        except AssertionError as exc:
+            exc_msg = str(exc)
         time.sleep(delay)
+    if exc_msg is not None:
+        isctest.log.error(exc_msg)
     if msg is None:
-        msg = f"{func.__module__}.{func.__qualname__} timed out after {timeout} s"
+        if exc_msg is not None:
+            msg = exc_msg
+        else:
+            msg = f"{func.__module__}.{func.__qualname__} timed out after {timeout} s"
     assert False, msg