add test

tests/unit-tests/data_utils.py

@@ -348,7 +348,7 @@ def generate_dummy_homogeneous_failure_graph(size='tiny', gen_mask=True, type='n
     generate a dummy homogeneous graph for failure case.
 
     In a homogeneous graph, the node type should be ["_N"] and the edge type should be [("_N", "_E", "_N")],
-    otherwise it should not be a valid homogeneous graph input. This function aims to generate
+    otherwise it should not be a valid homogeneous graph input. This function aims to generate a
     failure case for homogeneous graph input. When type="node", it will generate a graph with
     ["_N"] node type and [("_N", "_E", "_N"), ("_N", "fake_E", "_N")] edge type. When type="edge",
     it will generate a graph with ["_N", "fake_N"] node type and [("_N", "_E", "_N")] edge type.