Unit tests for Kruskal and Prim

src-test/org/graphstream/algorithm/test/TestKruskalPrim.java

+package org.graphstream.algorithm.test;
+
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
+import org.graphstream.algorithm.Kruskal;
+import org.graphstream.algorithm.Prim;
+import org.graphstream.graph.Edge;
+import org.graphstream.graph.Graph;
+import org.graphstream.graph.implementations.SingleGraph;
+import org.junit.Test;
+
+public class TestKruskalPrim {
+//       B-----8-----C-----7-----D
+//      /|          / \          |\
+//     / |         /   \         | \
+//    4  |        2     \        |  9
+//   /   |       /       \       |   \
+//  /    |      /         \      |    \
+// A    11     I           4    14     E
+//  \    |    / \           \    |    /
+//   \   |   /   \           \   |   /
+//    8  |  7     6           \  |  10
+//     \ | /       \           \ | /
+//      \|/         \           \|/
+//       H-----1-----G-----2-----F
+	
+	public static Graph toyGraph() {
+		String[] eIds = {"AB", "AH", "BH", "BC", "HI", "HG", "IC", "IG", "CD", "CF", "GF", "DF", "DE", "FE"};
+		int[] weights = {4, 8, 11, 8, 7, 1, 2, 6, 7, 4, 2, 14, 9, 10};
+		Graph g = new SingleGraph("test", false, true);
+		for (int i = 0; i < eIds.length; i++) {
+			String eId = eIds[i];
+			Edge e = g.addEdge(eId, eId.substring(0, 1), eId.substring(1, 2));
+			e.addAttribute("weight", weights[i]);
+		}
+		return g;
+	}
+	
+	@Test
+	public void toyTest() {
+		Graph g = toyGraph();
+		Kruskal k = new Kruskal("weight", "kruskal");
+		k.init(g);
+		k.compute();
+		helper(k, g, 37.0, 8);
+		
+		Prim p = new Prim("weight", "prim");
+		p.init(g);
+		p.compute();
+		helper(p, g, 37.0, 8);
+		
+		// remove the lightest edge
+		g.removeEdge("HG");
+		k.compute();
+		helper(k, g, 43.0, 8);
+		p.compute();
+		helper(p, g, 43.0, 8);
+		
+		// now cut the graph in 2 CC
+		g.removeEdge("BC");
+		g.removeEdge("HI");
+		k.compute();
+		helper(k, g, 36.0, 7);
+		p.compute();
+		helper(p, g, 36.0, 7);
+	}
+	
+	public void helper(Kruskal k, Graph g, double expectedWeight, int expectedCount) {
+		assertEquals(expectedWeight, k.getTreeWeight(), 0);
+		int edgeCount = 0;
+		for (Edge e : k.getTreeEdges()) {
+			boolean b = e.getAttribute(k.getFlagAttribute()); 
+			assertTrue(b);
+			edgeCount++;
+		}
+		assertEquals(expectedCount, edgeCount);
+		
+		edgeCount = 0;
+		double treeWeight = 0;
+		for (Edge e : g.getEachEdge()) {
+			boolean b = e.getAttribute(k.getFlagAttribute());
+			if (b) {
+				edgeCount++;
+				treeWeight += e.getNumber("weight");
+			}
+		}
+		assertEquals(expectedWeight, treeWeight, 0);
+		assertEquals(expectedCount, edgeCount);
+	}
+}