Minor docstring touchups and test refactor for `is_path` (#5967)

* Touch up docstring.

* Condense conditional.

* Minor refactor of ispath test - parametrize and rm redundant.

* Add release note.

* Update networkx/classes/function.py

Co-authored-by: Dan Schult <dschult@colgate.edu>

Co-authored-by: Dan Schult <dschult@colgate.edu>

2 files changed, 15 insertions, 19 deletions

diff --git a/networkx/classes/function.py b/networkx/classes/function.py
index d1277cf6..8e949a36 100644
--- a/networkx/classes/function.py
+++ b/networkx/classes/function.py
@@ -1243,19 +1243,17 @@ def is_path(G, path):
     G : graph
         A NetworkX graph.
 
-    path: list
-        A list of node labels which defines the path to traverse
+    path : list
+        A list of nodes which defines the path to traverse
 
     Returns
     -------
-    isPath: bool
-        A boolean representing whether or not the path exists
+    bool
+        True if `path` is a valid path in `G`
 
     """
     for node, nbr in nx.utils.pairwise(path):
-        if node not in G:
-            return False
-        if nbr not in G[node]:
+        if (node not in G) or (nbr not in G[node]):
             return False
     return True
 
diff --git a/networkx/classes/tests/test_function.py b/networkx/classes/tests/test_function.py
index bb961abd..704253f7 100644
--- a/networkx/classes/tests/test_function.py
+++ b/networkx/classes/tests/test_function.py
@@ -736,19 +736,17 @@ def test_pathweight():
         pytest.raises(nx.NetworkXNoPath, nx.path_weight, graph, invalid_path, "cost")
 
 
-def test_ispath():
+@pytest.mark.parametrize(
+    "G", (nx.Graph(), nx.DiGraph(), nx.MultiGraph(), nx.MultiDiGraph())
+)
+def test_ispath(G):
+    G.add_edges_from([(1, 2), (2, 3), (1, 2), (3, 4)])
     valid_path = [1, 2, 3, 4]
-    invalid_path = [1, 2, 4, 3]
-    another_invalid_path = [1, 2, 3, 4, 5]
-    yet_another_invalid_path = [1, 2, 5, 3, 4]
-    graphs = [nx.Graph(), nx.DiGraph(), nx.MultiGraph(), nx.MultiDiGraph()]
-    edges = [(1, 2), (2, 3), (1, 2), (3, 4)]
-    for graph in graphs:
-        graph.add_edges_from(edges)
-        assert nx.is_path(graph, valid_path)
-        assert not nx.is_path(graph, invalid_path)
-        assert not nx.is_path(graph, another_invalid_path)
-        assert not nx.is_path(graph, yet_another_invalid_path)
+    invalid_path = [1, 2, 4, 3]  # wrong node order
+    another_invalid_path = [1, 2, 3, 4, 5]  # contains node not in G
+    assert nx.is_path(G, valid_path)
+    assert not nx.is_path(G, invalid_path)
+    assert not nx.is_path(G, another_invalid_path)
 
 
 @pytest.mark.parametrize("G", (nx.Graph(), nx.DiGraph()))