From f546e7d06589a5ab00ab44c8aea569ffa790efc3 Mon Sep 17 00:00:00 2001
From: Thomas Michelat <thomas.michelat@xfel.eu>
Date: Mon, 20 Jan 2025 15:06:10 +0100
Subject: [PATCH] handle failure generating summary data

---
 damnit/ctxsupport/damnit_ctx.py |  8 +++++++-
 tests/test_backend.py           | 22 ++++++++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/damnit/ctxsupport/damnit_ctx.py b/damnit/ctxsupport/damnit_ctx.py
index b0c8dc9e..08b6fabf 100644
--- a/damnit/ctxsupport/damnit_ctx.py
+++ b/damnit/ctxsupport/damnit_ctx.py
@@ -4,6 +4,7 @@
 than the DAMNIT code in general, to allow running context files in other Python
 environments.
 """
+import logging
 import re
 import sys
 from collections.abc import Sequence
@@ -15,6 +16,8 @@
 
 __all__ = ["RunData", "Variable", "Cell"]
 
+log = logging.getLogger(__name__)
+
 
 THUMBNAIL_SIZE = 300 # px
 
@@ -169,7 +172,10 @@ def get_summary(self):
         if self.summary_value is not None:
             return self.summary_value
         elif self.summary is not None:
-            return np.asarray(getattr(np, self.summary)(self.data))
+            try:
+                return np.asarray(getattr(np, self.summary)(self.data))
+            except Exception:
+                log.error("Failed to produce summary data", exc_info=True)
 
         return None
 
diff --git a/tests/test_backend.py b/tests/test_backend.py
index cb63753f..0ffc20c8 100644
--- a/tests/test_backend.py
+++ b/tests/test_backend.py
@@ -538,6 +538,28 @@ def var3(run):
 
         assert f['.reduced/var3'][()] == 4
 
+
+def test_results_empty_array(mock_run, tmp_path, caplog):
+    # test failing summary
+    empty_array = """
+    from damnit_ctx import Variable
+
+    @Variable(title='Foo', summary='max')
+    def foo(run):
+        import numpy as np
+        return np.array([])
+    """
+    ctx = mkcontext(empty_array)
+    with caplog.at_level(logging.ERROR):
+        results = ctx.execute(mock_run, 1000, 123, {})
+        results.save_hdf5(tmp_path / 'results.h5', reduced_only=True)
+
+        # One warning about foo should have been logged
+        assert len(caplog.records) == 1
+        assert caplog.records[0].levelname == "ERROR"
+        assert caplog.records[0].msg == "Failed to produce summary data"
+
+
 @pytest.mark.skip(reason="Depending on user variables is currently disabled")
 def test_results_with_user_vars(mock_ctx_user, mock_user_vars, mock_run, caplog):