public void TopologicalSort_on_self_ref_can_break_cycle()
{
var vertexOne = new Vertex {
Id = 1
};
var edgeOne = new Edge {
Id = 1
};
var graph = new Multigraph <Vertex, Edge>();
graph.AddVertex(vertexOne);
// 1 -> {1}
graph.AddEdge(vertexOne, vertexOne, edgeOne);
Assert.Equal(
new[] { vertexOne },
graph.TopologicalSort(
(from, to, edges) =>
(from == vertexOne) &&
(to == vertexOne) &&
(edges.Intersect(new[] { edgeOne }).Count() == 1)).ToArray());
}
public void TopologicalSort_on_simple_graph_returns_all_vertices_in_order()
{
var vertexOne = new Vertex {
Id = 1
};
var vertexTwo = new Vertex {
Id = 2
};
var vertexThree = new Vertex {
Id = 3
};
var edgeOne = new Edge {
Id = 1
};
var edgeTwo = new Edge {
Id = 2
};
var graph = new Multigraph <Vertex, Edge>();
graph.AddVertices(new[] { vertexOne, vertexTwo, vertexThree });
// 2-> {1}
graph.AddEdge(vertexTwo, vertexOne, edgeOne);
// 1 -> {3}
graph.AddEdge(vertexOne, vertexThree, edgeTwo);
Assert.Equal(
new[] { vertexTwo, vertexOne, vertexThree },
graph.TopologicalSort().ToArray());
}
public void TopologicalSort_throws_with_formatted_message_when_cycle_cannot_be_broken()
{
const string message = "Formatted cycle";
var vertexOne = new Vertex {
Id = 1
};
var vertexTwo = new Vertex {
Id = 2
};
var vertexThree = new Vertex {
Id = 3
};
var edgeOne = new Edge {
Id = 1
};
var edgeTwo = new Edge {
Id = 2
};
var edgeThree = new Edge {
Id = 3
};
var graph = new Multigraph <Vertex, Edge>();
graph.AddVertices(new[] { vertexOne, vertexTwo, vertexThree });
// 1 -> {2}
graph.AddEdge(vertexOne, vertexTwo, edgeOne);
// 2 -> {3}
graph.AddEdge(vertexTwo, vertexThree, edgeTwo);
// 3 -> {1}
graph.AddEdge(vertexThree, vertexOne, edgeThree);
Dictionary <Vertex, Tuple <Vertex, Vertex, IEnumerable <Edge> > > cycleData = null;
string formatter(IEnumerable <Tuple <Vertex, Vertex, IEnumerable <Edge> > > data)
{
cycleData = data.ToDictionary(entry => entry.Item1);
return(message);
}
Assert.Equal(
CoreStrings.CircularDependency(message),
Assert.Throws <InvalidOperationException>(() => graph.TopologicalSort(formatter)).Message);
Assert.Equal(3, cycleData.Count());
Assert.Equal(vertexTwo, cycleData[vertexOne].Item2);
Assert.Equal(new[] { edgeOne }, cycleData[vertexOne].Item3);
Assert.Equal(vertexThree, cycleData[vertexTwo].Item2);
Assert.Equal(new[] { edgeTwo }, cycleData[vertexTwo].Item3);
Assert.Equal(vertexOne, cycleData[vertexThree].Item2);
Assert.Equal(new[] { edgeThree }, cycleData[vertexThree].Item3);
}
public void TopologicalSort_can_break_simple_cycle()
{
var vertexOne = new Vertex
{
Id = 1
};
var vertexTwo = new Vertex
{
Id = 2
};
var vertexThree = new Vertex
{
Id = 3
};
var edgeOne = new Edge
{
Id = 1
};
var edgeTwo = new Edge
{
Id = 2
};
var edgeThree = new Edge
{
Id = 3
};
var graph = new Multigraph <Vertex, Edge>();
graph.AddVertices(new[] { vertexOne, vertexTwo, vertexThree });
// 1 -> {2}
graph.AddEdge(vertexOne, vertexTwo, edgeOne);
// 2 -> {3}
graph.AddEdge(vertexTwo, vertexThree, edgeTwo);
// 3 -> {1}
graph.AddEdge(vertexThree, vertexOne, edgeThree);
Assert.Equal(
new[] { vertexOne, vertexTwo, vertexThree },
graph.TopologicalSort(
(from, to, edges) =>
(from == vertexThree) &&
(to == vertexOne) &&
(edges.Single() == edgeThree)).ToArray());
}
public void TopologicalSort_throws_with_default_message_when_cycle_cannot_be_broken()
{
var vertexOne = new Vertex
{
Id = 1
};
var vertexTwo = new Vertex
{
Id = 2
};
var vertexThree = new Vertex
{
Id = 3
};
var edgeOne = new Edge
{
Id = 1
};
var edgeTwo = new Edge
{
Id = 2
};
var edgeThree = new Edge
{
Id = 3
};
var graph = new Multigraph <Vertex, Edge>();
graph.AddVertices(new[] { vertexOne, vertexTwo, vertexThree });
// 1 -> {2}
graph.AddEdge(vertexOne, vertexTwo, edgeOne);
// 2 -> {3}
graph.AddEdge(vertexTwo, vertexThree, edgeTwo);
// 3 -> {1}
graph.AddEdge(vertexThree, vertexOne, edgeThree);
Assert.Equal(
CoreStrings.CircularDependency(
string.Join(" -> ", new[] { vertexOne, vertexTwo, vertexThree, vertexOne }.Select(v => v.ToString()))),
Assert.Throws <InvalidOperationException>(() => graph.TopologicalSort()).Message);
}
public void TopologicalSort_on_graph_with_no_edges_returns_all_vertices()
{
var vertexOne = new Vertex {
Id = 1
};
var vertexTwo = new Vertex {
Id = 2
};
var vertexThree = new Vertex {
Id = 3
};
var graph = new Multigraph <Vertex, Edge>();
graph.AddVertices(new[] { vertexOne, vertexTwo, vertexThree });
var result = graph.TopologicalSort();
Assert.Equal(3, result.Count());
Assert.Equal(3, result.Intersect(new[] { vertexOne, vertexTwo, vertexThree }).Count());
}
public void TopologicalSort_can_break_two_cycles()
{
var vertexOne = new Vertex {
Id = 1
};
var vertexTwo = new Vertex {
Id = 2
};
var vertexThree = new Vertex {
Id = 3
};
var vertexFour = new Vertex {
Id = 4
};
var vertexFive = new Vertex {
Id = 5
};
var edgeOne = new Edge {
Id = 1
};
var edgeTwo = new Edge {
Id = 2
};
var edgeThree = new Edge {
Id = 3
};
var edgeFour = new Edge {
Id = 4
};
var edgeFive = new Edge {
Id = 5
};
var edgeSix = new Edge {
Id = 6
};
var graph = new Multigraph <Vertex, Edge>();
graph.AddVertices(new[] { vertexOne, vertexTwo, vertexThree, vertexFour, vertexFive });
// 1 -> {2, 4}
graph.AddEdge(vertexOne, vertexTwo, edgeOne);
graph.AddEdge(vertexOne, vertexFour, edgeTwo);
// 2 -> {3}
graph.AddEdge(vertexTwo, vertexThree, edgeThree);
// 3 -> {1}
graph.AddEdge(vertexThree, vertexOne, edgeFour);
// 4 -> {5}
graph.AddEdge(vertexFour, vertexFive, edgeFive);
// 5 -> {1}
graph.AddEdge(vertexFive, vertexOne, edgeSix);
Assert.Equal(
new[] { vertexTwo, vertexThree, vertexOne, vertexFour, vertexFive },
graph.TopologicalSort(
(from, to, edges) =>
{
var edge = edges.Single();
return((edge == edgeOne) || (edge == edgeSix));
}).ToArray());
}
