public FastestPathTable FindShortestPaths(FindShortestPathsRequest request)
{
_findShortestPathsRequestValidator.ValidateAndThrowErrors(request);
ValidateNodes(request.Nodes, request.PrimaryNodeId);
var fastestPathTable = CreateFastestPathTable(request.Nodes, request.PrimaryNodeId);
var visitedNodeIds = new HashSet <string>();
var nodesById = request.Nodes.ToDictionary(n => n.Id);
var rowsById = fastestPathTable.Rows.ToDictionary(r => r.NodeId);
while (visitedNodeIds.Count < request.Nodes.Count - 1)
{
var lowestCostNodeId = FindLowestCostNodeId(fastestPathTable, visitedNodeIds);
// Catches graphs that aren't connected...
if (lowestCostNodeId == null)
{
break;
}
UpdateNeighborCosts(rowsById, visitedNodeIds, nodesById[lowestCostNodeId]);
visitedNodeIds.Add(lowestCostNodeId);
}
return(fastestPathTable);
}
public void ShouldThrowError_WhenGivenNullNodeCollection()
{
// Arrange
var dijkstraService = CreateService();
var request = new FindShortestPathsRequest {
Nodes = null, PrimaryNodeId = "A"
};
// Act
Func <FastestPathTable> result1 = () => dijkstraService.FindShortestPaths(request);
// Assert
result1.Should().Throw <UserReportableException>().WithMessage(BellErrorMessageKeys.VALIDATION_ERRORS);
}
public void ShouldThrowError_WhenPrimaryNodeIdDoesNotExistInNodeCollection()
{
// Arrange
var nodes = GenerateUndirectedGraphNodes();
var dijkstraService = CreateService();
var request = new FindShortestPathsRequest {
Nodes = nodes, PrimaryNodeId = "SOME_OTHER_NODE_ID"
};
// Act
Func <FastestPathTable> result = () => dijkstraService.FindShortestPaths(request);
// Assert
result.Should().Throw <UserReportableException>().WithMessage(ErrorMessageKeys.ERROR_NODE_ID_NOT_FOUND_IN_COLLECTION);
}
public void ShouldGenerateValidTable_WhenGivenUnconnectedGraphNodes()
{
// Arrange
var nodes = GenerateUndirectedGraphNodes();
nodes.Add(new Node {
Id = "F", Neighbors = null
});
var expectedResult = new FastestPathTable()
{
PrimaryNodeId = "A",
Rows = new List <FastestPathRow>
{
new FastestPathRow {
NodeId = "A", LowestCost = 0, NeighborNodeId = null
},
new FastestPathRow {
NodeId = "B", LowestCost = 3, NeighborNodeId = "D"
},
new FastestPathRow {
NodeId = "C", LowestCost = 7, NeighborNodeId = "E"
},
new FastestPathRow {
NodeId = "D", LowestCost = 1, NeighborNodeId = "A"
},
new FastestPathRow {
NodeId = "E", LowestCost = 2, NeighborNodeId = "D"
},
new FastestPathRow {
NodeId = "F", LowestCost = int.MaxValue, NeighborNodeId = null
}
}
};
var dijkstraService = CreateService();
var request = new FindShortestPathsRequest {
Nodes = nodes, PrimaryNodeId = "A"
};
// Act
var results = dijkstraService.FindShortestPaths(request);
// Assert
results.Should().BeEquivalentTo(expectedResult);
}
public void ShouldThrowError_WhenGivenUnmatchingCostsForNeighbors()
{
// Arrange
var nodes = GenerateUndirectedGraphNodes();
nodes[1].Neighbors[0].Cost++;
var dijkstraService = CreateService();
var request = new FindShortestPathsRequest {
Nodes = nodes, PrimaryNodeId = "A"
};
// Act
Func <FastestPathTable> result = () => dijkstraService.FindShortestPaths(request);
// Assert
result.Should().Throw <UserReportableException>().WithMessage(ErrorMessageKeys.ERROR_UNMATCHING_EDGE_COSTS);
}
public void ShouldThrowError_WhenGivenDuplicateNeighborNodeIds()
{
// Arrange
var nodes = GenerateUndirectedGraphNodes();
nodes[1].Neighbors[1].NodeId = nodes[1].Neighbors[3].NodeId;
var dijkstraService = CreateService();
var request = new FindShortestPathsRequest {
Nodes = nodes, PrimaryNodeId = "A"
};
// Act
Func <FastestPathTable> result = () => dijkstraService.FindShortestPaths(request);
// Assert
result.Should().Throw <UserReportableException>().WithMessage(ErrorMessageKeys.ERROR_DUPLICATE_NEIGHBOR_NODE_ID);
}
public void ShouldThrowError_WhenGivenBlankNodeIds()
{
// Arrange
var nodes = GenerateUndirectedGraphNodes();
nodes[2].Id = " ";
var dijkstraService = CreateService();
var request = new FindShortestPathsRequest {
Nodes = nodes, PrimaryNodeId = "A"
};
// Act
Func <FastestPathTable> result = () => dijkstraService.FindShortestPaths(request);
// Assert
result.Should().Throw <UserReportableException>().WithMessage(BellErrorMessageKeys.ERROR_STRING_ONLY_WHITE_SPACE);
}
public void ShouldGenerateValidTable_WhenGivenDirectedGraphNodes()
{
// Arrange
var nodes = GenerateUndirectedGraphNodes();
// Remove the neighbor E from node D to make it directed (D->E)...
var nodeDNeighbors = nodes.FirstOrDefault(n => n.Id == "D").Neighbors;
nodeDNeighbors.RemoveAll(n => n.NodeId == "E");
var expectedResult = new FastestPathTable()
{
PrimaryNodeId = "A",
Rows = new List <FastestPathRow>
{
new FastestPathRow {
NodeId = "A", LowestCost = 0, NeighborNodeId = null
},
new FastestPathRow {
NodeId = "B", LowestCost = 3, NeighborNodeId = "D"
},
new FastestPathRow {
NodeId = "C", LowestCost = 8, NeighborNodeId = "B"
},
new FastestPathRow {
NodeId = "D", LowestCost = 1, NeighborNodeId = "A"
},
new FastestPathRow {
NodeId = "E", LowestCost = 5, NeighborNodeId = "B"
}
}
};
var dijkstraService = CreateService();
var request = new FindShortestPathsRequest {
Nodes = nodes, PrimaryNodeId = "A"
};
// Act
var results = dijkstraService.FindShortestPaths(request);
// Assert
results.Should().BeEquivalentTo(expectedResult);
}
