TST: added test for empty parents

unittests/test_variable_substitutions.py

@@ -83,3 +83,18 @@ def test_substitutions_parents(crawler_2):
     assert len(parents) == 2
     assert parents[0].name == "Experiment"
     assert parents[1].name == "Month_05"
+
+
+def test_empty_parents(crawler_2):
+    # This is a test for:
+    # https://gitlab.com/caosdb/caosdb-crawler/-/issues/8
+
+    subd = crawler_2.debug_tree[dircheckstr(
+        "File", "ExperimentalData", "220512_data.dat")]
+
+    parents = subd[1]["RecordWithoutParents"].get_parents()
+    assert len(parents) == 0
+
+    parents = subd[1]["RecordThatGetsParentsLater"].get_parents()
+    assert len(parents) == 1
+    assert parents[0].name == "Month_05"