diff --git a/src/main/org/insa/algo/shortestpath/BellmanFordAlgorithm.java b/src/main/org/insa/algo/shortestpath/BellmanFordAlgorithm.java
index e423b9e..fddac4f 100644
--- a/src/main/org/insa/algo/shortestpath/BellmanFordAlgorithm.java
+++ b/src/main/org/insa/algo/shortestpath/BellmanFordAlgorithm.java
@@ -24,7 +24,7 @@ public class BellmanFordAlgorithm extends ShortestPathAlgorithm {
         ShortestPathData data = getInputData();
         Graph graph = data.getGraph();
 
-        final int nbNodes = graph.getNodes().size();
+        final int nbNodes = graph.size();
 
         // Initialize array of distances.
         double[] distances = new double[nbNodes];
@@ -41,8 +41,8 @@ public class BellmanFordAlgorithm extends ShortestPathAlgorithm {
         boolean found = false;
         for (int i = 0; !found && i < nbNodes; ++i) {
             found = true;
-            for (Node node: graph.getNodes()) {
-                for (Arc arc: node.getSuccessors()) {
+            for (Node node: graph) {
+                for (Arc arc: node) {
 
                     // Small test to check allowed roads...
                     if (!data.isAllowed(arc)) {
diff --git a/src/main/org/insa/algo/utils/BinaryHeap.java b/src/main/org/insa/algo/utils/BinaryHeap.java
index 09a208f..814c02a 100644
--- a/src/main/org/insa/algo/utils/BinaryHeap.java
+++ b/src/main/org/insa/algo/utils/BinaryHeap.java
@@ -1,9 +1,9 @@
 //
 // ******************PUBLIC OPERATIONS*********************
-// void insert( x )       --> Insert x
+// void insert( x ) --> Insert x
 // Comparable deleteMin( )--> Return and remove smallest item
-// Comparable findMin( )  --> Return smallest item
-// boolean isEmpty( )     --> Return true if empty; else false
+// Comparable findMin( ) --> Return smallest item
+// boolean isEmpty( ) --> Return true if empty; else false
 // ******************ERRORS********************************
 // Throws RuntimeException for findMin and deleteMin when empty
 
@@ -60,20 +60,6 @@ public class BinaryHeap<E extends Comparable<E>> {
         }
     }
 
-    /**
-     * @return true if the heap is empty, false otherwise.
-     */
-    public boolean isEmpty() {
-        return this.currentSize == 0;
-    }
-
-    /**
-     * @return Current size (number of elements) of this heap.
-     */
-    public int size() {
-        return this.currentSize;
-    }
-
     /**
      * @return Index of the parent of the given index.
      */
@@ -88,17 +74,6 @@ public class BinaryHeap<E extends Comparable<E>> {
         return index * 2 + 1;
     }
 
-    /**
-     * Insert the given element into the heap.
-     * 
-     * @param x Item to insert.
-     */
-    public void insert(E x) {
-        int index = this.currentSize++;
-        this.arraySet(index, x);
-        this.percolateUp(index);
-    }
-
     /**
      * Internal method to percolate up in the heap.
      * 
@@ -151,6 +126,41 @@ public class BinaryHeap<E extends Comparable<E>> {
         }
     }
 
+    /**
+     * @return true if the heap is empty, false otherwise.
+     */
+    public boolean isEmpty() {
+        return this.currentSize == 0;
+    }
+
+    /**
+     * @return Current size (number of elements) of this heap.
+     */
+    public int size() {
+        return this.currentSize;
+    }
+
+    /**
+     * Insert the given element into the heap.
+     * 
+     * @param x Item to insert.
+     */
+    public void add(E x) {
+        int index = this.currentSize++;
+        this.arraySet(index, x);
+        this.percolateUp(index);
+    }
+
+    /**
+     * Tell the binary heap that the given element has been modified and should be
+     * re-positioned inside the heap.
+     * 
+     * @param x Item to update.
+     */
+    public void update(E x) {
+        // TODO:
+    }
+
     /**
      * Find the smallest item in the heap.
      * 
@@ -160,7 +170,7 @@ public class BinaryHeap<E extends Comparable<E>> {
      */
     public E findMin() throws RuntimeException {
         if (isEmpty())
-            throw new RuntimeException("Empty binary heap");
+            throw new RuntimeException("Empty binary heap.");
         return this.array.get(0);
     }
 
diff --git a/src/main/org/insa/algo/weakconnectivity/WeaklyConnectedComponentsAlgorithm.java b/src/main/org/insa/algo/weakconnectivity/WeaklyConnectedComponentsAlgorithm.java
index 436c8f8..04f5138 100644
--- a/src/main/org/insa/algo/weakconnectivity/WeaklyConnectedComponentsAlgorithm.java
+++ b/src/main/org/insa/algo/weakconnectivity/WeaklyConnectedComponentsAlgorithm.java
@@ -4,7 +4,6 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.LinkedList;
-import java.util.List;
 import java.util.Queue;
 
 import org.insa.algo.AbstractAlgorithm;
@@ -72,14 +71,14 @@ public class WeaklyConnectedComponentsAlgorithm
      *         graph.
      */
     protected ArrayList<HashSet<Integer>> createUndirectedGraph() {
-        int nNodes = getInputData().getGraph().getNodes().size();
+        int nNodes = getInputData().getGraph().size();
         ArrayList<HashSet<Integer>> res = new ArrayList<HashSet<Integer>>(nNodes);
         for (int i = 0; i < nNodes; ++i) {
             res.add(new HashSet<Integer>());
         }
 
-        for (Node node: getInputData().getGraph().getNodes()) {
-            for (Arc arc: node.getSuccessors()) {
+        for (Node node: getInputData().getGraph()) {
+            for (Arc arc: node) {
                 res.get(node.getId()).add(arc.getDestination().getId());
                 if (arc.getRoadInformation().isOneWay()) {
                     res.get(arc.getDestination().getId()).add(node.getId());
@@ -100,27 +99,27 @@ public class WeaklyConnectedComponentsAlgorithm
      * @return
      */
     protected ArrayList<Node> bfs(ArrayList<HashSet<Integer>> ugraph, boolean[] marked, int cur) {
-        List<Node> nodes = getInputData().getGraph().getNodes();
+        Graph graph = getInputData().getGraph();
         ArrayList<Node> component = new ArrayList<Node>();
 
         // Using a queue because we are doing a BFS
         Queue<Integer> queue = new LinkedList<Integer>();
 
         // Notify observers about the current component.
-        notifyStartComponent(nodes.get(cur));
+        notifyStartComponent(graph.get(cur));
 
         // Add original node and loop until the queue is empty.
         queue.add(cur);
         marked[cur] = true;
         while (!queue.isEmpty()) {
-            Node node = nodes.get(queue.remove());
+            Node node = graph.get(queue.remove());
             component.add(node);
 
             // Notify observers
             notifyNewNodeInComponent(node);
 
             for (Integer destId: ugraph.get(node.getId())) {
-                Node dest = nodes.get(destId);
+                Node dest = graph.get(destId);
                 if (!marked[dest.getId()]) {
                     queue.add(destId);
                     marked[destId] = true;
@@ -138,7 +137,7 @@ public class WeaklyConnectedComponentsAlgorithm
 
         Graph graph = getInputData().getGraph();
         ArrayList<HashSet<Integer>> ugraph = createUndirectedGraph();
-        boolean[] marked = new boolean[graph.getNodes().size()];
+        boolean[] marked = new boolean[graph.size()];
         Arrays.fill(marked, false);
 
         ArrayList<ArrayList<Node>> components = new ArrayList<ArrayList<Node>>();
diff --git a/src/main/org/insa/graph/Graph.java b/src/main/org/insa/graph/Graph.java
index 11dadb5..570dcbb 100644
--- a/src/main/org/insa/graph/Graph.java
+++ b/src/main/org/insa/graph/Graph.java
@@ -1,7 +1,7 @@
 package org.insa.graph;
 
 import java.util.ArrayList;
-import java.util.Collections;
+import java.util.Iterator;
 import java.util.List;
 
 /**
@@ -11,7 +11,7 @@ import java.util.List;
  * holds a list of nodes and each node holds a list of its successors.
  *
  */
-public class Graph {
+public class Graph implements Iterable<Node> {
 
     // Map identifier.
     private final String mapId;
@@ -48,10 +48,28 @@ public class Graph {
     }
 
     /**
-     * @return Immutable view of the list of nodes of this graph.
+     * Fetch the node with the given ID.
+     * 
+     * Complexity: O(1).
+     * 
+     * @param id ID of the node to fetch.
+     * 
+     * @return Node with the given ID.
      */
-    public List<Node> getNodes() {
-        return Collections.unmodifiableList(nodes);
+    public Node get(int id) {
+        return this.nodes.get(id);
+    }
+
+    /**
+     * @return Number of nodes in this graph.
+     */
+    public int size() {
+        return this.nodes.size();
+    }
+
+    @Override
+    public Iterator<Node> iterator() {
+        return this.nodes.iterator();
     }
 
     /**
@@ -78,7 +96,7 @@ public class Graph {
         }
         for (Node node: nodes) {
             Node orig = trNodes.get(node.getId());
-            for (Arc arc: node.getSuccessors()) {
+            for (Arc arc: node) {
                 if (arc.getRoadInformation().isOneWay()) {
                     Node dest = trNodes.get(arc.getDestination().getId());
                     dest.addSuccessor(new ArcBackward(new ArcForward(orig, dest, arc.getLength(),
diff --git a/src/main/org/insa/graph/Node.java b/src/main/org/insa/graph/Node.java
index 4ba7917..3722bc9 100644
--- a/src/main/org/insa/graph/Node.java
+++ b/src/main/org/insa/graph/Node.java
@@ -2,7 +2,7 @@ package org.insa.graph;
 
 import java.util.ArrayList;
 import java.util.Collections;
-import java.util.List;
+import java.util.Iterator;
 
 /**
  * Class representing a Node in a {@link Graph}.
@@ -13,7 +13,7 @@ import java.util.List;
  * Nodes are comparable based on their ID.
  *
  */
-public class Node implements Comparable<Node> {
+public class Node implements Comparable<Node>, Iterable<Arc> {
 
     /**
      * Link the two given nodes with one or two arcs (depending on roadInformation),
@@ -94,10 +94,22 @@ public class Node implements Comparable<Node> {
     }
 
     /**
-     * @return Immutable view of the list of successors of this node.
+     * @return Number of successors of this node.
      */
-    public List<Arc> getSuccessors() {
-        return Collections.unmodifiableList(successors);
+    public int getNumberOfSuccessors() {
+        return this.successors.size();
+    }
+
+    /**
+     * @return true if this node has at least one successor.
+     */
+    public boolean hasSuccessors() {
+        return !this.successors.isEmpty();
+    }
+
+    @Override
+    public Iterator<Arc> iterator() {
+        return this.successors.iterator();
     }
 
     /**
diff --git a/src/main/org/insa/graph/io/BinaryPathReader.java b/src/main/org/insa/graph/io/BinaryPathReader.java
index 91e7478..bb3336f 100644
--- a/src/main/org/insa/graph/io/BinaryPathReader.java
+++ b/src/main/org/insa/graph/io/BinaryPathReader.java
@@ -70,7 +70,7 @@ public class BinaryPathReader extends BinaryReader implements PathReader {
      * @throws IndexOutOfBoundsException if the node is not in the graph.
      */
     protected Node readNode(Graph graph) throws IOException {
-        return graph.getNodes().get(dis.readInt());
+        return graph.get(dis.readInt());
     }
 
 }
diff --git a/src/main/org/insa/graphics/MainWindow.java b/src/main/org/insa/graphics/MainWindow.java
index 04409bf..b10f643 100644
--- a/src/main/org/insa/graphics/MainWindow.java
+++ b/src/main/org/insa/graphics/MainWindow.java
@@ -602,8 +602,8 @@ public class MainWindow extends JFrame {
                     // name that are right-to-left (e.g. arabic names).
                     info += " - " + graph.getMapName() + "\u200e";
                 }
-                info += ", " + graph.getNodes().size() + " nodes, "
-                        + graph.getGraphInformation().getArcCount() + " arcs.";
+                info += ", " + graph.size() + " nodes, " + graph.getGraphInformation().getArcCount()
+                        + " arcs.";
                 graphInfoPanel.setText(info);
 
                 drawGraph();
diff --git a/src/main/org/insa/graphics/NodesInputPanel.java b/src/main/org/insa/graphics/NodesInputPanel.java
index 54cd9f8..b9a020e 100644
--- a/src/main/org/insa/graphics/NodesInputPanel.java
+++ b/src/main/org/insa/graphics/NodesInputPanel.java
@@ -65,7 +65,7 @@ public class NodesInputPanel extends JPanel
         public Node findClosestNode(Point point) {
             Node minNode = null;
             double minDis = Double.POSITIVE_INFINITY;
-            for (Node node: graph.getNodes()) {
+            for (Node node: graph) {
                 double dlon = point.getLongitude() - node.getPoint().getLongitude();
                 double dlat = point.getLatitude() - node.getPoint().getLatitude();
                 double dis = dlon * dlon + dlat * dlat; // No need to square
@@ -308,7 +308,7 @@ public class NodesInputPanel extends JPanel
      */
     protected Node getNodeForInput(JTextField textfield) {
         try {
-            Node node = graph.getNodes().get(Integer.valueOf(textfield.getText().trim()));
+            Node node = graph.get(Integer.valueOf(textfield.getText().trim()));
             return node;
         }
         catch (IllegalArgumentException | IndexOutOfBoundsException ex) {
diff --git a/src/main/org/insa/graphics/drawing/components/BasicDrawing.java b/src/main/org/insa/graphics/drawing/components/BasicDrawing.java
index 2e9444e..88a87b9 100644
--- a/src/main/org/insa/graphics/drawing/components/BasicDrawing.java
+++ b/src/main/org/insa/graphics/drawing/components/BasicDrawing.java
@@ -614,7 +614,7 @@ public class BasicDrawing extends JPanel implements Drawing {
 
     @Override
     public void drawGraph(Graph graph, GraphPalette palette) {
-        int repaintModulo = Math.max(1, graph.getNodes().size() / 100);
+        int repaintModulo = Math.max(1, graph.size() / 100);
 
         // Initialize the buffered image
 
@@ -625,8 +625,8 @@ public class BasicDrawing extends JPanel implements Drawing {
         this.removeMouseMotionListener(zoomAndPanListener);
         this.removeMouseWheelListener(zoomAndPanListener);
 
-        for (Node node: graph.getNodes()) {
-            for (Arc arc: node.getSuccessors()) {
+        for (Node node: graph) {
+            for (Arc arc: node) {
                 // Draw arcs only if there are one-way arcs or if origin is lower than
                 // destination, avoid drawing two-ways arc twice.
                 if (arc.getRoadInformation().isOneWay()
diff --git a/src/test/org/insa/algo/utils/BinaryHeapTest.java b/src/test/org/insa/algo/utils/BinaryHeapTest.java
index 47a8345..3501e04 100644
--- a/src/test/org/insa/algo/utils/BinaryHeapTest.java
+++ b/src/test/org/insa/algo/utils/BinaryHeapTest.java
@@ -11,29 +11,68 @@ import org.junit.Test;
 
 public class BinaryHeapTest {
 
-    private int[] data1 = IntStream.range(0, 20).toArray();
-    private int[] data2 = { 8, 1, 6, 3, 4, 5, 9 };
+    class MutableInteger implements Comparable<MutableInteger> {
 
-    private BinaryHeap<Integer> heap1, heap2;
+        // Actual value
+        private int value;
+
+        public MutableInteger(int value) {
+            this.value = value;
+        }
+
+        /**
+         * @return The integer value stored inside this MutableInteger.
+         */
+        public int get() {
+            return this.value;
+        }
+
+        /**
+         * Update the integer value stored inside this MutableInteger.
+         * 
+         * @param value New value to set.
+         */
+        public void set(int value) {
+            this.value = value;
+        }
+
+        @Override
+        public int compareTo(MutableInteger other) {
+            return Integer.compare(this.value, other.value);
+        }
+
+    };
+
+    // Raw data arrays.
+    private MutableInteger[] data1 = IntStream.range(0, 20).mapToObj(MutableInteger::new)
+            .toArray(MutableInteger[]::new);
+    private MutableInteger[] data2 = Arrays.stream(new int[] { 8, 1, 6, 3, 4, 5, 9 })
+            .mapToObj(MutableInteger::new).toArray(MutableInteger[]::new);
+
+    // Actual heap.
+    private BinaryHeap<MutableInteger> heap1, heap2;
 
     @Before
     public void init() {
         // Create the range heap
-        this.heap1 = new BinaryHeap<Integer>();
-        this.heap2 = new BinaryHeap<Integer>();
+        this.heap1 = new BinaryHeap<>();
+        this.heap2 = new BinaryHeap<>();
 
-        for (int v: data1)
-            this.heap1.insert(v);
-        for (int v: data2)
-            this.heap2.insert(v);
+        for (MutableInteger v: data1) {
+            this.heap1.add(v);
+        }
+
+        for (MutableInteger v: data2) {
+            this.heap2.add(v);
+        }
     }
 
     @Test
     public void testInsert() {
-        BinaryHeap<Integer> heap = new BinaryHeap<Integer>();
+        BinaryHeap<MutableInteger> heap = new BinaryHeap<>();
         int size = 0;
-        for (int x: data1) {
-            heap.insert(x);
+        for (MutableInteger x: data1) {
+            heap.add(x);
             size += 1;
             assertEquals(heap.size(), size);
         }
@@ -41,8 +80,8 @@ public class BinaryHeapTest {
 
         heap = new BinaryHeap<>();
         size = 0;
-        for (int x: data2) {
-            heap.insert(x);
+        for (MutableInteger x: data2) {
+            heap.add(x);
             size += 1;
             assertEquals(heap.size(), size);
         }
@@ -52,11 +91,10 @@ public class BinaryHeapTest {
     @Test
     public void testDeleteMin() {
         // range 1 (sorted)
-        int[] range1 = data1;
-        int size = range1.length;
+        int size = data1.length;
         assertEquals(heap1.size(), size);
-        for (int x: range1) {
-            assertEquals(heap1.deleteMin().intValue(), x);
+        for (MutableInteger x: data1) {
+            assertEquals(heap1.deleteMin(), x);
             size -= 1;
             assertEquals(heap1.size(), size);
         }
@@ -64,12 +102,12 @@ public class BinaryHeapTest {
         assertTrue(heap1.isEmpty());
 
         // range 2 (was not sorted)
-        int[] range2 = Arrays.copyOf(data2, data2.length);
+        MutableInteger[] range2 = Arrays.copyOf(data2, data2.length);
         Arrays.sort(range2);
         size = range2.length;
         assertEquals(heap2.size(), size);
-        for (int x: range2) {
-            assertEquals(heap2.deleteMin().intValue(), x);
+        for (MutableInteger x: range2) {
+            assertEquals(heap2.deleteMin().get(), x.get());
             size -= 1;
             assertEquals(heap2.size(), size);
         }
@@ -77,4 +115,12 @@ public class BinaryHeapTest {
         assertTrue(heap2.isEmpty());
     }
 
+    @Test
+    public void testUpdate() {
+        MutableInteger newMin = data2[data2.length - 1];
+        newMin.set(0);
+        heap2.update(newMin);
+        assertEquals(heap2.findMin(), newMin);
+    }
+
 }
diff --git a/src/test/org/insa/graph/GraphTest.java b/src/test/org/insa/graph/GraphTest.java
index 915eaf2..25e934c 100644
--- a/src/test/org/insa/graph/GraphTest.java
+++ b/src/test/org/insa/graph/GraphTest.java
@@ -62,7 +62,7 @@ public class GraphTest {
      */
     private List<Arc> getArcsBetween(Node a, Node b) {
         List<Arc> arcs = new ArrayList<>();
-        for (Arc arc: a.getSuccessors()) {
+        for (Arc arc: a) {
             if (arc.getDestination().equals(b)) {
                 arcs.add(arc);
             }
@@ -76,53 +76,33 @@ public class GraphTest {
 
         // Basic asserts...
         assertEquals("R/" + graph.getMapId(), transpose.getMapId());
-        assertEquals(graph.getNodes().size(), transpose.getNodes().size());
+        assertEquals(graph.size(), transpose.size());
 
         final int expNbSucc[] = { 4, 2, 2, 4, 2 };
         for (int i = 0; i < expNbSucc.length; ++i) {
-            assertEquals(expNbSucc[i], transpose.getNodes().get(i).getSuccessors().size());
+            assertEquals(expNbSucc[i], transpose.get(i).getNumberOfSuccessors());
         }
 
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(0), transpose.getNodes().get(1)).size(), 1);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(0), transpose.getNodes().get(2)).size(), 1);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(0), transpose.getNodes().get(3)).size(), 1);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(0), transpose.getNodes().get(4)).size(), 1);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(1), transpose.getNodes().get(0)).size(), 1);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(1), transpose.getNodes().get(2)).size(), 1);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(1), transpose.getNodes().get(3)).size(), 0);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(1), transpose.getNodes().get(4)).size(), 0);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(2), transpose.getNodes().get(0)).size(), 1);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(2), transpose.getNodes().get(1)).size(), 1);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(2), transpose.getNodes().get(3)).size(), 0);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(2), transpose.getNodes().get(4)).size(), 0);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(3), transpose.getNodes().get(0)).size(), 1);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(3), transpose.getNodes().get(1)).size(), 0);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(3), transpose.getNodes().get(2)).size(), 3);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(3), transpose.getNodes().get(4)).size(), 0);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(4), transpose.getNodes().get(0)).size(), 1);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(4), transpose.getNodes().get(1)).size(), 0);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(4), transpose.getNodes().get(2)).size(), 0);
-        assertEquals(
-                getArcsBetween(transpose.getNodes().get(4), transpose.getNodes().get(3)).size(), 1);
+        assertEquals(getArcsBetween(transpose.get(0), transpose.get(1)).size(), 1);
+        assertEquals(getArcsBetween(transpose.get(0), transpose.get(2)).size(), 1);
+        assertEquals(getArcsBetween(transpose.get(0), transpose.get(3)).size(), 1);
+        assertEquals(getArcsBetween(transpose.get(0), transpose.get(4)).size(), 1);
+        assertEquals(getArcsBetween(transpose.get(1), transpose.get(0)).size(), 1);
+        assertEquals(getArcsBetween(transpose.get(1), transpose.get(2)).size(), 1);
+        assertEquals(getArcsBetween(transpose.get(1), transpose.get(3)).size(), 0);
+        assertEquals(getArcsBetween(transpose.get(1), transpose.get(4)).size(), 0);
+        assertEquals(getArcsBetween(transpose.get(2), transpose.get(0)).size(), 1);
+        assertEquals(getArcsBetween(transpose.get(2), transpose.get(1)).size(), 1);
+        assertEquals(getArcsBetween(transpose.get(2), transpose.get(3)).size(), 0);
+        assertEquals(getArcsBetween(transpose.get(2), transpose.get(4)).size(), 0);
+        assertEquals(getArcsBetween(transpose.get(3), transpose.get(0)).size(), 1);
+        assertEquals(getArcsBetween(transpose.get(3), transpose.get(1)).size(), 0);
+        assertEquals(getArcsBetween(transpose.get(3), transpose.get(2)).size(), 3);
+        assertEquals(getArcsBetween(transpose.get(3), transpose.get(4)).size(), 0);
+        assertEquals(getArcsBetween(transpose.get(4), transpose.get(0)).size(), 1);
+        assertEquals(getArcsBetween(transpose.get(4), transpose.get(1)).size(), 0);
+        assertEquals(getArcsBetween(transpose.get(4), transpose.get(2)).size(), 0);
+        assertEquals(getArcsBetween(transpose.get(4), transpose.get(3)).size(), 1);
 
     }
 }
diff --git a/src/test/org/insa/graph/NodeTest.java b/src/test/org/insa/graph/NodeTest.java
index eeba7ef..c64a5dd 100644
--- a/src/test/org/insa/graph/NodeTest.java
+++ b/src/test/org/insa/graph/NodeTest.java
@@ -18,7 +18,7 @@ public class NodeTest {
     public void initAll() throws IOException {
 
         // Create nodes
-        nodes = new Node[5];
+        nodes = new Node[6];
         for (int i = 0; i < nodes.length; ++i) {
             nodes[i] = new Node(i, null);
         }
@@ -54,7 +54,7 @@ public class NodeTest {
      * @return The first arc between from a to b, or null.
      */
     private Arc getFirstArcBetween(Node a, Node b) {
-        for (Arc arc: a.getSuccessors()) {
+        for (Arc arc: a) {
             if (arc.getDestination().equals(b)) {
                 return arc;
             }
@@ -63,13 +63,25 @@ public class NodeTest {
     }
 
     @Test
-    public void testLinkNodes() {
-        final int[] expNbSucc = { 4, 2, 5, 2, 1 };
+    public void testGetNumberOfSuccessors() {
+        final int[] expNbSucc = { 4, 2, 5, 2, 1, 0 };
         assertEquals(nodes.length, expNbSucc.length);
         for (int i = 0; i < expNbSucc.length; ++i) {
-            assertEquals(nodes[i].getSuccessors().size(), expNbSucc[i]);
+            assertEquals(nodes[i].getNumberOfSuccessors(), expNbSucc[i]);
         }
+    }
 
+    @Test
+    public void testHasSuccessors() {
+        final int[] expNbSucc = { 4, 2, 5, 2, 1, 0 };
+        assertEquals(nodes.length, expNbSucc.length);
+        for (int i = 0; i < expNbSucc.length; ++i) {
+            assertEquals(nodes[i].hasSuccessors(), expNbSucc[i] != 0);
+        }
+    }
+
+    @Test
+    public void testLinkNodes() {
         assertEquals(getFirstArcBetween(nodes[0], nodes[1]).getRoadInformation(),
                 getFirstArcBetween(nodes[1], nodes[0]).getRoadInformation());
     }