A Biconnected Component Algorithm for graphstream

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

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+package org.graphstream.algorithm.test;
+
+import org.graphstream.algorithm.HopcroftTarjanBiconnectedComponents;
+import org.graphstream.graph.Graph;
+import org.graphstream.graph.implementations.DefaultGraph;
+import org.graphstream.stream.file.FileSourceDGS;
+import org.junit.Assert;
+import org.junit.Test;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Collections;
+
+public class TestHopcroftTarjanBiconnectedComponents {
+
+    @Test
+    public void testBasic() throws Exception {
+        Graph g = new DefaultGraph("g");
+        load(g, "data/bcc-basic.dgs", true);
+
+        HopcroftTarjanBiconnectedComponents bcc = new HopcroftTarjanBiconnectedComponents(g, g.getNode("C"));
+
+        bcc.compute();
+
+        check(bcc, createBCC("A", "B", "C"), createBCC("D", "E", "F"), createBCC("C", "D"));
+    }
+
+    @Test
+    public void testSingleDFSStrand() {
+        Graph g = new DefaultGraph("g");
+        load(g, "data/bcc-basic.dgs", true);
+
+        HopcroftTarjanBiconnectedComponents bcc = new HopcroftTarjanBiconnectedComponents(g);
+
+        bcc.compute();
+
+        check(bcc, createBCC("A", "B", "C"), createBCC("D", "E", "F"), createBCC("C", "D"));
+    }
+
+    @Test
+    public void testSingleNode() {
+        Graph g = new DefaultGraph("g");
+
+        g.addNode("A");
+
+        HopcroftTarjanBiconnectedComponents bcc = new HopcroftTarjanBiconnectedComponents(g);
+
+        bcc.compute();
+
+        check(bcc, createBCC("A"));
+    }
+
+    @Test
+    public void testNodePair() {
+        Graph g = new DefaultGraph("g");
+
+        g.addNode("A");
+        g.addNode("B");
+        g.addEdge("AB","A","B");
+
+        HopcroftTarjanBiconnectedComponents bcc = new HopcroftTarjanBiconnectedComponents(g);
+
+        bcc.compute();
+
+        check(bcc, createBCC("A","B"));
+    }
+
+    @Test
+    public void testNormal() {
+        Graph g = new DefaultGraph("g");
+        load(g, "data/bcc-normal.dgs", true);
+
+        HopcroftTarjanBiconnectedComponents bcc = new HopcroftTarjanBiconnectedComponents(g, g.getNode("H"));
+
+        bcc.compute();
+
+        check(bcc, createBCC("A", "B", "C", "D"), createBCC("D", "E"), createBCC("E", "F"), createBCC("F", "G"), createBCC("G", "H", "I", "J", "K", "L"), createBCC("G", "M"), createBCC("L", "N"));
+    }
+
+    @Test
+    public void testNormalSubtreeWithoutCutVertex() {
+        Graph g = new DefaultGraph("g");
+        load(g, "data/bcc-normal-subtree-wo-cut-vertex.dgs", true);
+
+        HopcroftTarjanBiconnectedComponents bcc = new HopcroftTarjanBiconnectedComponents(g, g.getNode("K"));
+
+        bcc.compute();
+
+        check(bcc, createBCC("A", "B", "C", "F"), createBCC("F", "G"), createBCC("G", "H", "I", "J", "K", "L"), createBCC("G", "M"), createBCC("L", "N"));
+    }
+
+    static FileSourceDGS load(Graph g, String dgsPath, boolean all) {
+        FileSourceDGS dgs = new FileSourceDGS();
+        InputStream in = TestHopcroftTarjanBiconnectedComponents.class.getResourceAsStream(dgsPath);
+
+        dgs.addSink(g);
+
+        if (all) {
+            try {
+                dgs.readAll(in);
+            } catch (IOException e) {
+                Assert.fail(e.getMessage());
+            }
+        } else {
+            try {
+                dgs.begin(in);
+            } catch (IOException e) {
+                Assert.fail(e.getMessage());
+            }
+        }
+
+        return dgs;
+    }
+
+    static String[] createBCC(String... nodes) {
+        return nodes;
+    }
+
+    static void check(HopcroftTarjanBiconnectedComponents algo, String[]... bccs) {
+        Assert.assertEquals(bccs.length, algo.getBiconnectedComponentsCount());
+
+        for (int i = 0; i < bccs.length; i++) {
+            for (int j = 1; j < bccs[i].length; j++) {
+                ArrayList<HopcroftTarjanBiconnectedComponents.BiconnectedComponent> cc1 = algo.getBiconnectedComponentsOf(bccs[i][0]);
+                ArrayList<HopcroftTarjanBiconnectedComponents.BiconnectedComponent> cc2 = algo.getBiconnectedComponentsOf(bccs[i][j]);
+
+                Assert.assertFalse(Collections.disjoint(cc1, cc2));
+            }
+
+            for (int j = i + 1; j < bccs.length; j++) {
+                ArrayList<HopcroftTarjanBiconnectedComponents.BiconnectedComponent> cc1 = algo.getBiconnectedComponentsOf(bccs[i][0]);
+                ArrayList<HopcroftTarjanBiconnectedComponents.BiconnectedComponent> cc2 = algo.getBiconnectedComponentsOf(bccs[j][0]);
+
+                Assert.assertTrue(Collections.disjoint(cc1, cc2) || (cc1.size() > 1 || cc2.size() > 1));
+            }
+        }
+    }
+}

src-test/org/graphstream/algorithm/test/data/bcc-basic.dgs

@@ -0,0 +1,19 @@
+DGS004
+null 0 0
+
+an A
+an B
+an C
+
+ae AB A B
+ae AC A C
+ae BC B C
+
+an D
+an E
+an F
+
+ae CD C D
+ae DE D E
+ae DF D F
+ae EF E F

src-test/org/graphstream/algorithm/test/data/bcc-normal-subtree-wo-cut-vertex.dgs

@@ -0,0 +1,38 @@
+DGS004
+null 0 0
+
+an A
+an B
+an C
+
+an F
+
+an G
+an H
+an I
+an J
+an K
+an L
+
+an M
+
+an N
+
+ae AB A B
+ae AC A C
+ae BF B F
+ae CF C F
+
+ae FG F G
+
+ae GH G H
+ae HI H I
+ae HJ H J
+ae IJ I J
+ae JK J K
+ae KL K L
+ae LG L G
+
+ae GM G M
+
+ae LN L N

src-test/org/graphstream/algorithm/test/data/bcc-normal.dgs

@@ -0,0 +1,44 @@
+DGS004
+null 0 0
+
+an A
+an B
+an C
+an D
+
+an E
+an F
+
+an G
+an H
+an I
+an J
+an K
+an L
+
+an M
+
+an N
+
+ae AB A B
+ae AC A C
+ae BD B D
+ae CD C D
+
+ae DE D E
+
+ae EF E F
+
+ae FG F G
+
+ae GH G H
+ae HI H I
+ae HJ H J
+ae IJ I J
+ae JK J K
+ae KL K L
+ae LG L G
+
+ae GM G M
+
+ae LN L N