Add Graph example test

src/main.rs

@@ -1,4 +1,4 @@
-#[derive(Copy, Clone, PartialEq, Eq)]
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
 struct Vertex(usize);
 
 #[derive(Copy, Clone, PartialEq, Eq)]
@@ -73,5 +73,56 @@ impl Graph {
 }
 
 fn main() {
-    println!("Hello, world!");
+    // TODO: Move this graph example into one or more tests.
+    let mut graph = Graph{
+        // TODO: The initializations should happen in an initializer or constructor
+        vertex_incidence_headers: vec![],
+        next_incidences: vec![],
+        incidence_vertices: vec![],
+    };
+    let vertices: [Vertex; 10] = core::array::from_fn(|_| graph.add_vertex());
+    graph.add_edge(vertices[0], vertices[1]);
+    graph.add_edge(vertices[1], vertices[2]);
+    graph.add_edge(vertices[1], vertices[3]);
+    graph.add_edge(vertices[1], vertices[4]);
+    graph.add_edge(vertices[2], vertices[4]);
+    graph.add_edge(vertices[2], vertices[5]);
+    graph.add_edge(vertices[2], vertices[6]);
+    graph.add_edge(vertices[3], vertices[6]);
+    graph.add_edge(vertices[4], vertices[7]);
+    graph.add_edge(vertices[4], vertices[8]);
+    graph.add_edge(vertices[5], vertices[9]);
+    graph.add_edge(vertices[6], vertices[9]);
+    graph.add_edge(vertices[7], vertices[8]);
+    graph.add_edge(vertices[7], vertices[9]);
+
+    assert_eq!(graph.vertex_count(), 10, "vertex count");
+    assert_eq!(graph.edge_count(), 14, "edge count");
+    let expected_degrees = [1, 4, 4, 2, 4, 2, 3, 3, 2, 3];
+    for i in 0..graph.vertex_count() {
+        assert_eq!(graph.degree(vertices[i]), expected_degrees[i],
+                   "degree of {:?}", vertices[i]);
+    }
+
+    assert_eq!(graph.are_adjacent(vertices[0], vertices[1]), true,
+               "adjacency of {:?} and {:?}", vertices[0], vertices[1]);
+    assert_eq!(graph.are_adjacent(vertices[9], vertices[5]), true,
+               "adjacency of {:?} and {:?}", vertices[0], vertices[5]);
+    assert_eq!(graph.are_adjacent(vertices[9], vertices[3]), false,
+               "adjacency of {:?} and {:?}", vertices[9], vertices[3]);
+
+    for i in 0..vertices.len() {
+        let exp = match i {
+            2 => continue,
+            1 | 4 | 5 | 6 => true,
+            _ => false,
+        };
+        assert_eq!(graph.are_adjacent(vertices[2], vertices[i]), exp,
+                   "adjacency of {:?} and {:?}", vertices[2], vertices[i]);
+        assert_eq!(graph.are_adjacent(vertices[i], vertices[2]), exp,
+                   "adjacency of {:?} and {:?}", vertices[i], vertices[2]);
+    }
+
+    // TODO: test Dijkstra's algorithm starting at 0 and at another vertex.
+    let expected_distances_to_v0 = [0, 1, 2, 2, 2, 3, 3, 3, 3, 4];
 }