diff --git a/test/digraph_test.h b/test/digraph_test.h
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+/* -*- C++ -*-
+ *
+ * This file is a part of LEMON, a generic C++ optimization library
+ *
+ * Copyright (C) 2003-2007
+ * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport
+ * (Egervary Research Group on Combinatorial Optimization, EGRES).
+ *
+ * Permission to use, modify and distribute this software is granted
+ * provided that this copyright notice appears in all copies. For
+ * precise terms see the accompanying LICENSE file.
+ *
+ * This software is provided "AS IS" with no warranty of any kind,
+ * express or implied, and with no claim as to its suitability for any
+ * purpose.
+ *
+ */
+
+#ifndef LEMON_TEST_GRAPH_TEST_H
+#define LEMON_TEST_GRAPH_TEST_H
+
+//#include <lemon/graph_utils.h>
+#include "test_tools.h"
+
+//! \ingroup misc
+//! \file
+//! \brief Some utility and test cases to test digraph classes.
+namespace lemon {
+
+  ///Structure returned by \ref addPetersen().
+
+  ///Structure returned by \ref addPetersen().
+  ///
+  template<class Digraph> 
+  struct PetStruct
+  {
+    ///Vector containing the outer nodes.
+    std::vector<typename Digraph::Node> outer;
+    ///Vector containing the inner nodes.
+    std::vector<typename Digraph::Node> inner;
+    ///Vector containing the edges of the inner circle.
+    std::vector<typename Digraph::Arc> incir;
+    ///Vector containing the edges of the outer circle.
+    std::vector<typename Digraph::Arc> outcir;
+    ///Vector containing the chord edges.
+    std::vector<typename Digraph::Arc> chords;
+  };
+
+
+
+  ///Adds a Petersen graph to \c G.
+
+  ///Adds a Petersen graph to \c G.
+  ///\return The nodes and edges of the generated graph.
+
+  template<typename Digraph>
+  PetStruct<Digraph> addPetersen(Digraph &G,int num = 5)
+  {
+    PetStruct<Digraph> n;
+
+    for(int i=0;i<num;i++) {
+      n.outer.push_back(G.addNode());
+      n.inner.push_back(G.addNode());
+    }
+
+    for(int i=0;i<num;i++) {
+      n.chords.push_back(G.addArc(n.outer[i],n.inner[i]));
+      n.outcir.push_back(G.addArc(n.outer[i],n.outer[(i+1) % num]));
+      n.incir.push_back(G.addArc(n.inner[i],n.inner[(i+2) % num]));
+    }
+    return n;
+  }
+
+  /// \brief Adds to the digraph the reverse pair of all edges.
+  ///
+  /// Adds to the digraph the reverse pair of all edges.
+  ///
+  template<class Digraph> 
+  void bidirDigraph(Digraph &G)
+  {
+    typedef typename Digraph::Arc Arc;
+    typedef typename Digraph::ArcIt ArcIt;
+  
+    std::vector<Arc> ee;
+  
+    for(ArcIt e(G);e!=INVALID;++e) ee.push_back(e);
+
+    for(typename std::vector<Arc>::iterator p=ee.begin();p!=ee.end();p++)
+      G.addArc(G.target(*p),G.source(*p));
+  }
+
+
+  /// \brief Checks the bidirectioned Petersen graph.
+  ///
+  ///  Checks the bidirectioned Petersen graph.
+  ///
+  template<class Digraph> 
+  void checkBidirPetersen(Digraph &G, int num = 5)
+  {
+    typedef typename Digraph::Node Node;
+
+    typedef typename Digraph::ArcIt ArcIt;
+    typedef typename Digraph::NodeIt NodeIt;
+
+    checkDigraphNodeList(G, 2 * num);
+    checkDigraphArcList(G, 6 * num);
+
+    for(NodeIt n(G);n!=INVALID;++n) {
+      checkDigraphInArcList(G, n, 3);
+      checkDigraphOutArcList(G, n, 3);
+    }  
+  }
+
+  template<class Digraph> void checkDigraphNodeList(Digraph &G, int nn)
+  {
+    typename Digraph::NodeIt n(G);
+    for(int i=0;i<nn;i++) {
+      check(n!=INVALID,"Wrong Node list linking.");
+      ++n;
+    }
+    check(n==INVALID,"Wrong Node list linking.");
+  }
+
+  template<class Digraph>
+  void checkDigraphArcList(Digraph &G, int nn)
+  {
+    typedef typename Digraph::ArcIt ArcIt;
+
+    ArcIt e(G);
+    for(int i=0;i<nn;i++) {
+      check(e!=INVALID,"Wrong Arc list linking.");
+      ++e;
+    }
+    check(e==INVALID,"Wrong Arc list linking.");
+  }
+
+  template<class Digraph> 
+  void checkDigraphOutArcList(Digraph &G, typename Digraph::Node n, int nn)
+  {
+    typename Digraph::OutArcIt e(G,n);
+    for(int i=0;i<nn;i++) {
+      check(e!=INVALID,"Wrong OutArc list linking.");
+      check(n==G.source(e), "Wrong OutArc list linking.");
+      ++e;
+    }
+    check(e==INVALID,"Wrong OutArc list linking.");
+  }
+
+  template<class Digraph> void 
+  checkDigraphInArcList(Digraph &G, typename Digraph::Node n, int nn)
+  {
+    typename Digraph::InArcIt e(G,n);
+    for(int i=0;i<nn;i++) {
+      check(e!=INVALID,"Wrong InArc list linking.");
+      check(n==G.target(e), "Wrong InArc list linking.");
+      ++e;
+    }
+    check(e==INVALID,"Wrong InArc list linking.");
+  }
+
+  template <class Digraph> 
+  void checkDigraph() {
+    const int num = 5;
+    Digraph G;
+    addPetersen(G, num);
+    bidirDigraph(G);
+    checkBidirPetersen(G, num);
+  }
+
+  template <class Digraph> 
+  void checkDigraphIterators(const Digraph& digraph) {
+    typedef typename Digraph::Node Node;
+    typedef typename Digraph::NodeIt NodeIt;
+    typedef typename Digraph::Arc Arc;
+    typedef typename Digraph::ArcIt ArcIt;
+    typedef typename Digraph::InArcIt InArcIt;
+    typedef typename Digraph::OutArcIt OutArcIt;
+    //    typedef ConArcIt<Digraph> ConArcIt;
+  }
+
+  ///\file
+  ///\todo Check target(), source() as well;
+
+  
+} //namespace lemon
+
+
+#endif