Fix find_successor_node_by_edge (#1551)

* Fix bug

* Add the release note

---------

Co-authored-by: Ivan Carvalho <8753214+IvanIsCoding@users.noreply.github.com>
Co-authored-by: Ivan Carvalho <ivancarvalho@gatech.edu>

Author: jberg5

releasenotes/notes/fix-find-successor-bug-09d2a59f0c7fc00c.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixed a bug in `~rustworkx.PyDiGraph.find_successor_node_by_edge`  where
+    the method always returned the source node by mistake. Now, it returns
+    any of the successors, as originally intended.

src/digraph.rs

@@ -2359,7 +2359,7 @@ impl PyDiGraph {
             let edge_predicate_raw = predicate_callable(edge.weight())?;
             let edge_predicate: bool = edge_predicate_raw.extract(py)?;
             if edge_predicate {
-                return Ok(self.graph.node_weight(edge.source()).unwrap());
+                return Ok(self.graph.node_weight(edge.target()).unwrap());
             }
         }
         Err(NoSuitableNeighbors::new_err("No suitable neighbor"))

tests/digraph/test_edges.py

@@ -288,7 +288,7 @@ def compare_edges(edge):
             return "b to c" == edge
 
         res = dag.find_successor_node_by_edge(node_b, compare_edges)
-        self.assertEqual("b", res)
+        self.assertEqual("c", res)
 
     def test_find_successor_node_by_edge_no_match(self):
         dag = rustworkx.PyDiGraph()