fix(test): skip scalar-less tensorboard event files in resume checks

tests/functional_tests/python_test_utils/common.py

@@ -92,6 +92,32 @@ class SkipMetricError(Exception):
     """Raised if metric shall be skipped"""
 
 
+def _load_event_accumulators_with_scalars(
+    files: List[str],
+) -> List[event_accumulator.EventAccumulator]:
+    """Loads event-file accumulators that contain scalar data, preserving order.
+
+    A resumed training phase can emit a header-only TensorBoard event file with
+    zero scalars before the file that holds the actual metrics (for example when
+    the fault-tolerance launcher initializes a SummaryWriter ahead of logging).
+    Dropping scalar-less files keeps positional ``index`` selection aligned with
+    real run data instead of latching onto an empty file and yielding no metrics.
+
+    Args:
+        files: Event-file paths, ordered oldest-first.
+
+    Returns:
+        Reloaded accumulators that expose at least one scalar tag, in input order.
+    """
+    accumulators = []
+    for event_file in files:
+        ea = event_accumulator.EventAccumulator(event_file, size_guidance=SIZE_GUIDANCE)
+        ea.Reload()
+        if ea.Tags()["scalars"]:
+            accumulators.append(ea)
+    return accumulators
+
+
 def read_tb_logs_as_list(
     path, index: int = 0, train_iters: int = 50, start_idx: int = 1, step_size: int = 5
 ) -> Optional[Dict[str, GoldenValueMetric]]:
@@ -113,18 +139,21 @@ def read_tb_logs_as_list(
         return None
 
     files.sort(key=lambda x: os.path.getmtime(os.path.join(path, pathlib.Path(x).name)))
-    accumulators = []
 
-    if index == -1:
-        for event_file in files:
-            ea = event_accumulator.EventAccumulator(event_file, size_guidance=SIZE_GUIDANCE)
-            ea.Reload()
-            accumulators.append(ea)
-    else:
-        event_file = files[index]
-        ea = event_accumulator.EventAccumulator(event_file, size_guidance=SIZE_GUIDANCE)
-        ea.Reload()
-        accumulators.append(ea)
+    accumulators = _load_event_accumulators_with_scalars(files)
+
+    if not accumulators:
+        logger.error(f"No event file with scalar data found at: {path}")
+        return None
+
+    if index != -1:
+        if index >= len(accumulators):
+            logger.error(
+                f"Requested event-file index {index} but only {len(accumulators)} "
+                f"event file(s) with scalar data found at: {path}"
+            )
+            return None
+        accumulators = [accumulators[index]]
 
     summaries = {}
     for ea in accumulators: