diff --git a/case_utils/ontology/src/ontology_and_version_iris.py b/case_utils/ontology/src/ontology_and_version_iris.py
index 7ac429d..e85f0ff 100644
--- a/case_utils/ontology/src/ontology_and_version_iris.py
+++ b/case_utils/ontology/src/ontology_and_version_iris.py
@@ -29,6 +29,11 @@
 def concept_is_cdo_concept(n_concept: rdflib.URIRef) -> bool:
     """
     This function is purposefully distinct from the function used in case_validate.  Within this script, the publishing history of CASE and UCO is reviewed.
+
+    >>> concept_is_cdo_concept(rdflib.URIRef("http://example.org/ontology/Thing"))
+    False
+    >>> concept_is_cdo_concept(rdflib.URIRef("https://ontology.unifiedcyberontology.org/uco/core/UcoThing"))
+    True
     """
     concept_iri = str(n_concept)
     return (
diff --git a/tests/Makefile b/tests/Makefile
index c1c626e..f38243d 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -59,6 +59,11 @@ check: \
   check-mypy \
   check-isomorphic_diff \
   check-case_utils
+	source venv/bin/activate \
+	  && pytest \
+	    --doctest-modules \
+	    --log-level=DEBUG \
+	    $(top_srcdir)/case_utils
 	source venv/bin/activate \
 	  && pytest \
 	    --ignore case_utils \