diff --git a/tarjan_unittest.cc b/tarjan_unittest.cc
new file mode 100644
index 0000000..9c4d7a8
--- /dev/null
+++ b/tarjan_unittest.cc
@@ -0,0 +1,80 @@
+// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <utility>
+#include <gtest/gtest.h>
+#include "chromeos/obsolete_logging.h"
+#include "update_engine/graph_types.h"
+#include "update_engine/tarjan.h"
+#include "update_engine/utils.h"
+
+using std::make_pair;
+using std::pair;
+using std::set;
+using std::string;
+using std::vector;
+
+namespace chromeos_update_engine {
+
+class TarjanAlgorithmTest : public ::testing::Test {};
+
+TEST(TarjanAlgorithmTest, SimpleTest) {
+  const Vertex::Index n_a = 0;
+  const Vertex::Index n_b = 1;
+  const Vertex::Index n_c = 2;
+  const Vertex::Index n_d = 3;
+  const Vertex::Index n_e = 4;
+  const Vertex::Index n_f = 5;
+  const Vertex::Index n_g = 6;
+  const Vertex::Index n_h = 7;
+  const Graph::size_type kNodeCount = 8;
+
+  Graph graph(kNodeCount);
+  
+  graph[n_a].out_edges.insert(make_pair(n_e, EdgeProperties()));
+  graph[n_a].out_edges.insert(make_pair(n_f, EdgeProperties()));
+  graph[n_b].out_edges.insert(make_pair(n_a, EdgeProperties()));
+  graph[n_c].out_edges.insert(make_pair(n_d, EdgeProperties()));
+  graph[n_d].out_edges.insert(make_pair(n_e, EdgeProperties()));
+  graph[n_d].out_edges.insert(make_pair(n_f, EdgeProperties()));
+  graph[n_e].out_edges.insert(make_pair(n_b, EdgeProperties()));
+  graph[n_e].out_edges.insert(make_pair(n_c, EdgeProperties()));
+  graph[n_e].out_edges.insert(make_pair(n_f, EdgeProperties()));
+  graph[n_f].out_edges.insert(make_pair(n_g, EdgeProperties()));
+  graph[n_g].out_edges.insert(make_pair(n_h, EdgeProperties()));
+  graph[n_h].out_edges.insert(make_pair(n_g, EdgeProperties()));
+  
+  TarjanAlgorithm tarjan;
+  
+  for (Vertex::Index i = n_a; i <= n_e; i++) {
+    vector<Vertex::Index> vertex_indexes;
+    tarjan.Execute(i, &graph, &vertex_indexes);
+
+    EXPECT_EQ(5, vertex_indexes.size());
+    EXPECT_TRUE(utils::VectorContainsValue(vertex_indexes, n_a));
+    EXPECT_TRUE(utils::VectorContainsValue(vertex_indexes, n_b));
+    EXPECT_TRUE(utils::VectorContainsValue(vertex_indexes, n_c));
+    EXPECT_TRUE(utils::VectorContainsValue(vertex_indexes, n_d));
+    EXPECT_TRUE(utils::VectorContainsValue(vertex_indexes, n_e));
+  }
+  
+  {
+    vector<Vertex::Index> vertex_indexes;
+    tarjan.Execute(n_f, &graph, &vertex_indexes);
+    
+    EXPECT_EQ(1, vertex_indexes.size());
+    EXPECT_TRUE(utils::VectorContainsValue(vertex_indexes, n_f));
+  }
+  
+  for (Vertex::Index i = n_g; i <= n_h; i++) {
+    vector<Vertex::Index> vertex_indexes;
+    tarjan.Execute(i, &graph, &vertex_indexes);
+
+    EXPECT_EQ(2, vertex_indexes.size());
+    EXPECT_TRUE(utils::VectorContainsValue(vertex_indexes, n_g));
+    EXPECT_TRUE(utils::VectorContainsValue(vertex_indexes, n_h));
+  }
+}
+
+}  // namespace chromeos_update_engine