public void ClearAdjacencyGraph_InvalidatesOldNodes()
{
var solver = new PathSolver <Point, PathTestOption>(_testMap);
// Build a graph based on all three points.
solver.BuildAdjacencyGraph(new Point[] { _startPt, _reachableEndPt, _unreachableEndPt });
// Clear the graph, and then rebuild it with just one point.
solver.ClearAdjacencyGraph();
solver.BuildAdjacencyGraph(_startPt);
// Try to find a path to _unreachableEndPt. PathSolver should complain that it doesn't know about that point.
PathResult <Point> pathResult = null;
Assert.ThrowsException <PathfindingException>(() => pathResult = solver.FindPath(_startPt, _unreachableEndPt, PathTestOption.Normal));
}