package org.neo4j.graphalgo.path;
import static org.junit.Assert.fail;
import org.junit.Test;
import org.neo4j.graphalgo.CommonEvaluators;
import org.neo4j.graphalgo.GraphAlgoFactory;
import org.neo4j.graphalgo.PathFinder;
import org.neo4j.graphalgo.WeightedPath;
import org.neo4j.graphdb.Direction;
import org.neo4j.graphdb.Relationship;
import org.neo4j.kernel.Traversal;
import common.Neo4jAlgoTestCase;
public class TestDijkstra extends Neo4jAlgoTestCase
{
@Test
public void testSmallGraph()
{
/* Layout:
* (y)
* ^
* [2] _____[1]___
* \ v |
* (start)--[1]->(a)--[9]-->(x)<- (e)--[2]->(f)
* | ^ ^^ \ ^
* [1] ---[7][5][3] -[3] [1]
* v / | / \ /
* (b)--[1]-->(c)--[1]->(d)
*/
graph.makeEdge( "start", "a", "cost", (double) 1 );
graph.makeEdge( "a", "x", "cost", (double) 9 );
graph.makeEdge( "a", "b", "cost", (double) 1 );
graph.makeEdge( "b", "x", "cost", (double) 7 );
graph.makeEdge( "b", "c", "cost", (double) 1 );
graph.makeEdge( "c", "x", "cost", (double) 5 );
Relationship shortCTOXRelationship = graph.makeEdge( "c", "x", "cost", (double) 3 );
graph.makeEdge( "c", "d", "cost", (double) 1 );
graph.makeEdge( "d", "x", "cost", (double) 3 );
graph.makeEdge( "d", "e", "cost", (double) 1 );
graph.makeEdge( "e", "x", "cost", (double) 1 );
graph.makeEdge( "e", "f", "cost", (double) 2 );
graph.makeEdge( "x", "y", "cost", (double) 2 );
PathFinder<WeightedPath> finder = GraphAlgoFactory.dijkstra(
Traversal.expanderForTypes( MyRelTypes.R1, Direction.OUTGOING ),
CommonEvaluators.doubleCostEvaluator( "cost" ) );
// Assert that there are two matching paths
assertPaths( finder.findAllPaths( graph.getNode( "start" ), graph.getNode( "x" ) ),
"start,a,b,c,x", "start,a,b,c,d,e,x" );
// Assert that for the shorter one it picked the correct relationship
// of the two from (c) --> (x)
for ( WeightedPath path :
finder.findAllPaths( graph.getNode( "start" ), graph.getNode( "x" ) ) )
{
if ( getPathDef( path ).equals( "start,a,b,c,x" ) )
{
assertContainsRelationship( path, shortCTOXRelationship );
}
}
}
private void assertContainsRelationship( WeightedPath path,
Relationship relationship )
{
for ( Relationship rel : path.relationships() )
{
if ( rel.equals( relationship ) )
{
return;
}
}
fail( path + " should've contained " + relationship );
}
}