text: // Ceres Solver - A fast non-linear least squares minimizer
  // Copyright 2010, 2011, 2012 Google Inc. All rights reserved.
  // http://code.google.com/p/ceres-solver/
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are met:
  //
  // * Redistributions of source code must retain the above copyright notice,
  //   this list of conditions and the following disclaimer.
  // * Redistributions in binary form must reproduce the above copyright notice,
  //   this list of conditions and the following disclaimer in the documentation
  //   and/or other materials provided with the distribution.
  // * Neither the name of Google Inc. nor the names of its contributors may be
  //   used to endorse or promote products derived from this software without
  //   specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  // POSSIBILITY OF SUCH DAMAGE.
  //
  // Author: sameeragarwal@google.com (Sameer Agarwal)
  
  #include "ceres/graph.h"
  
  #include "gtest/gtest.h"
  #include "ceres/collections_port.h"
  #include "ceres/internal/scoped_ptr.h"
  
  namespace ceres {
  namespace internal {
  
  TEST(Graph, EmptyGraph) {
    Graph<int> graph;
    EXPECT_EQ(graph.vertices().size(), 0);
  }
  
  TEST(Graph, AddVertexAndEdge) {
    Graph<int> graph;
    graph.AddVertex(0, 1.0);
    graph.AddVertex(1, 2.0);
    graph.AddEdge(0, 1, 0.5);
  
    const HashSet<int>& vertices = graph.vertices();
    EXPECT_EQ(vertices.size(), 2);
    EXPECT_EQ(graph.VertexWeight(0), 1.0);
    EXPECT_EQ(graph.VertexWeight(1), 2.0);
    EXPECT_EQ(graph.Neighbors(0).size(), 1);
    EXPECT_EQ(graph.Neighbors(1).size(), 1);
    EXPECT_EQ(graph.EdgeWeight(0, 1), 0.5);
    EXPECT_EQ(graph.EdgeWeight(1, 0), 0.5);
  }
  
  TEST(Graph, AddVertexIdempotence) {
    Graph<int> graph;
    graph.AddVertex(0, 1.0);
    graph.AddVertex(1, 2.0);
    graph.AddEdge(0, 1, 0.5);
  
    const HashSet<int>& vertices = graph.vertices();
  
    EXPECT_EQ(vertices.size(), 2);
  
    // Try adding the vertex again with a new weight.
    graph.AddVertex(0, 3.0);
    EXPECT_EQ(vertices.size(), 2);
  
    // The vertex weight is reset.
    EXPECT_EQ(graph.VertexWeight(0), 3.0);
  
    // Rest of the graph remains the same.
    EXPECT_EQ(graph.VertexWeight(1), 2.0);
    EXPECT_EQ(graph.Neighbors(0).size(), 1);
    EXPECT_EQ(graph.Neighbors(1).size(), 1);
    EXPECT_EQ(graph.EdgeWeight(0, 1), 0.5);
    EXPECT_EQ(graph.EdgeWeight(1, 0), 0.5);
  }
  
  // Death tests don't work on Windows.
  // TODO(keir): Figure out why this test doesn't work on Windows.
  #ifndef _WIN32
  
  TEST(Graph, DieOnNonExistentVertex) {
    Graph<int> graph;
    graph.AddVertex(0, 1.0);
    graph.AddVertex(1, 2.0);
    graph.AddEdge(0, 1, 0.5);
  
    EXPECT_DEATH(graph.VertexWeight(2), "key not found");
    EXPECT_DEATH(graph.Neighbors(2), "key not found");
  }
  
  #endif  // _WIN32
  
  TEST(Graph, NonExistentEdge) {
    Graph<int> graph;
    graph.AddVertex(0, 1.0);
    graph.AddVertex(1, 2.0);
    graph.AddEdge(0, 1, 0.5);
  
    // Default value for non-existent edges is 0.
    EXPECT_EQ(graph.EdgeWeight(2, 3), 0);
  }
  
  }  // namespace internal
  }  // namespace ceres
  