From 46d81b7985229f97e3c2effc005774358e8b0260 Mon Sep 17 00:00:00 2001
From: Indeximal <indeximal@gmail.com>
Date: Wed, 8 Jun 2022 00:31:33 +0200
Subject: [PATCH] Added test for GraphMap::from_graph

---
 src/graphmap.rs   |  5 ++---
 tests/graphmap.rs | 21 ++++++++++++++++++++-
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/src/graphmap.rs b/src/graphmap.rs
index 92fe82590..4a9860c24 100644
--- a/src/graphmap.rs
+++ b/src/graphmap.rs
@@ -522,9 +522,8 @@ where
 
     /// Creates a `GraphMap` that corresponds to the given `Graph`.
     ///
-    /// Note that node and edge indices in the `Graph` are lost in this process,
-    /// but the weights are kept.
-    /// **Warning**: Parallel edges are lost, only the last one remains.
+    /// **Warning**: Nodes with the same weight are merged and only the last parallel edge
+    /// is kept, because node and edge indices in the `Graph` are lost in this process.
     ///
     /// Computes in **O(|V| + |E|)** time (average).
     pub fn from_graph<Ix>(graph: Graph<N, E, Ty, Ix>) -> Self
diff --git a/tests/graphmap.rs b/tests/graphmap.rs
index 07589419b..1426ea4db 100644
--- a/tests/graphmap.rs
+++ b/tests/graphmap.rs
@@ -119,7 +119,7 @@ fn remove_node() {
     graph.remove_node(2);
 
     let neighbors: Vec<u32> = graph.neighbors(1).collect();
-    assert_eq!(neighbors, [] as [u32; 0]);
+    assert_eq!(neighbors, []);
 
     let edges: Vec<(u32, u32, _)> = graph.all_edges().collect();
     assert_eq!(edges, []);
@@ -325,6 +325,25 @@ fn test_into_graph() {
     }
 }
 
+#[test]
+fn test_from_graph() {
+    let mut gr: Graph<u32, u32, Directed> = Graph::new();
+    let node_a = gr.add_node(12);
+    let node_b = gr.add_node(13);
+    let node_c = gr.add_node(14);
+    gr.add_edge(node_a, node_b, 1000);
+    gr.add_edge(node_b, node_c, 999);
+    gr.add_edge(node_c, node_a, 1111);
+    gr.add_node(42);
+    let gr = gr;
+
+    let graph: GraphMap<u32, u32, Directed> = GraphMap::from_graph(gr.clone());
+    println!("{}", Dot::new(&gr));
+    println!("{}", Dot::new(&graph));
+
+    assert!(petgraph::algo::is_isomorphic(&gr, &graph));
+}
+
 #[test]
 fn test_all_edges_mut() {
     // graph with edge weights equal to in+out