Add unit test for draw

Signed-off-by: Adam Li <[email protected]>

pywhy_graphs/algorithms/semi_directed_paths.py

@@ -120,17 +120,13 @@ def all_semi_directed_paths(G, source: Node, target: Node, cutoff: int = None):
         except TypeError:
             raise nx.NodeNotFound("target node %s not in graph" % target)
     if source in targets:
-        return []
+        return _empty_generator()
     if cutoff is None:
         cutoff = len(G) - 1
     if cutoff < 1:
-        return []
-    if source in targets:
         return _empty_generator()
     if cutoff is None:
         cutoff = len(G) - 1
-    if cutoff < 1:
-        return _empty_generator()
 
     return _all_semi_directed_paths_graph(G, source, targets, cutoff)
 

pywhy_graphs/viz/tests/test_draw.py

@@ -6,6 +6,26 @@
 from pywhy_graphs.viz import draw, timeseries_layout
 
 
+def test_draw_digraph():
+    """
+    Ensure the generated graph is a directed graph.
+
+    The number of edges between any two nodes should always be one.
+    """
+    # create a dummy graph x --> y <-- z and z --> x
+    graph = nx.DiGraph([("x", "y"), ("z", "y"), ("z", "x")])
+
+    # draw the graphs
+    dot = draw(graph)
+
+    # assert that the produced graph is a directed graph
+    assert "digraph" in dot.source
+
+    regex_pattern = "(?=(x -> y))"
+    matches = re.findall(regex_pattern, dot.source)
+    assert len(matches) == 1
+
+
 def test_draw_pos_is_fully_given():
     """
     Ensure the Graphviz pos="x,y!" attribute is generated by the draw function