public void GraphWithDisconnectedNodes_GetShortestPath_ThrowsArgumentException()
{
GraphNode source = new GraphNode(new Vector2(0f, 0f));
GraphNode destination = new GraphNode(new Vector2(10f, 10f));
Graph disconnectedGraph = new Graph();
disconnectedGraph.AddEdge(
new GraphEdge(source, new GraphNode(new Vector2(1f, 1f)))
);
disconnectedGraph.AddEdge(
new GraphEdge(new GraphNode(new Vector2(5f, 5f)), destination)
);
AStarAlgorithm astar = new AStarAlgorithm(disconnectedGraph);
// Should throw an argument exception, because it cannot
// calculate the shortest path between disconnected nodes.
astar.GetShortestPath(source, destination);
}
public void ConnectedGraph_GetDepthFirstEnumerable_StartsWithStartNode()
{
Graph graph = new Graph();
GraphNode start = new GraphNode(new Vector2(0, 0));
GraphNode finish = new GraphNode(new Vector2(1, 1));
graph.AddEdge(new GraphEdge(start, finish));
var enumerator = graph.GetDepthFirstEnumerable(start).GetEnumerator();
Assert.IsTrue(enumerator.Current == start,
"Enumerator did not start with the correct node");
}
public void ConnectedGraph_GetShortestPath_ReturnsCorrectPath()
{
// Create a graph with four nodes, connected in a straight line.
Graph graph = new Graph();
const int NodeCount = 4;
GraphNode start = new GraphNode(new Vector2(0f, 0f));
GraphNode midFirst = new GraphNode(new Vector2(1f, 1f));
GraphNode midSecond = new GraphNode(new Vector2(2f, 2f));
GraphNode destination = new GraphNode(new Vector2(3f, 3f));
graph.AddEdge(new GraphEdge(start, midFirst));
graph.AddEdge(new GraphEdge(midFirst, midSecond));
graph.AddEdge(new GraphEdge(midSecond, destination));
AStarAlgorithm astar = new AStarAlgorithm(graph);
IEnumerable<GraphNode> path =
astar.GetShortestPath(start, destination).Path;
Assert.IsTrue(path.Count() == NodeCount,
"Path has an invalid amount of nodes");
}
private static void CreateEdges(Graph graph, GraphNode[,] nodes, int x, int y,
int columns, int rows)
{
for (int i = x - 1; i < x + 2; i++)
{
for (int j = y - 1; j < y + 2; j++)
{
if (i > 0 && i < columns && j > 0 && j < rows &&
!(i == x && j == y))
{
graph.AddEdge(new GraphEdge(nodes[x, y], nodes[i, j]));
}
}
}
}
public void ConnectedGraph_GetDepthFirstEnumerable_TraversesCorrectAmountOfNodes()
{
const int EdgeCount = 4;
const int NodeCount = EdgeCount + 1;
Graph graph = new Graph();
GraphNode start = new GraphNode(new Vector2());
GraphNode currentSource = start;
GraphNode currentDestination;
for (int i = 0; i < EdgeCount; i++)
{
currentDestination = new GraphNode(new Vector2());
graph.AddEdge(new GraphEdge(currentSource, currentDestination));
currentSource = currentDestination;
}
var enumerator = graph.GetDepthFirstEnumerable(start).GetEnumerator();
int actualCount = 1;
while (enumerator.MoveNext())
{
actualCount++;
}
Assert.AreEqual(NodeCount, actualCount,
"DeothFirstEnumerator did not traverse the correct amount of nodes.");
}