Add a test for LineSearchMinimizer

Ensures that a quadratic function can be minimizer to zero
and the final cost is reported correctly.

Change-Id: Ib03752b627988dc8038566ed1fa444b7d9d2fd2d

internal/ceres/CMakeLists.txt

diff --git a/internal/ceres/CMakeLists.txt b/internal/ceres/CMakeLists.txt
index 0f6c4be..c85cbec 100644
--- a/internal/ceres/CMakeLists.txt
+++ b/internal/ceres/CMakeLists.txt
@@ -324,6 +324,7 @@
   ceres_test(jet)
   ceres_test(levenberg_marquardt_strategy)
   ceres_test(dogleg_strategy)
+  ceres_test(line_search_minimizer)
   ceres_test(line_search_preprocessor)
   ceres_test(local_parameterization)
   ceres_test(loss_function)

internal/ceres/line_search_minimizer_test.cc

diff --git a/internal/ceres/line_search_minimizer_test.cc b/internal/ceres/line_search_minimizer_test.cc
new file mode 100644
index 0000000..aa83769
--- /dev/null
+++ b/internal/ceres/line_search_minimizer_test.cc
@@ -0,0 +1,67 @@
+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2017 Google Inc. All rights reserved.
+// http://ceres-solver.org/
+//
+// 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 <cmath>
+#include <cstdlib>
+
+#include "ceres/ceres.h"
+#include "glog/logging.h"
+#include "gtest/gtest.h"
+
+namespace ceres {
+namespace internal {
+
+class QuadraticFirstOrderFunction : public ceres::FirstOrderFunction {
+ public:
+  virtual bool Evaluate(const double* parameters,
+                        double* cost,
+                        double* gradient) const {
+
+    cost[0] = parameters[0] * parameters[0];
+    if (gradient != NULL) {
+      gradient[0] = 2.0 * parameters[0];
+    }
+    return true;
+  }
+
+  virtual int NumParameters() const { return 1; }
+};
+
+TEST(LineSearchMinimizerTest, FinalCostIsZero) {
+  double parameters[1] = {2.0};
+  ceres::GradientProblem problem(new QuadraticFirstOrderFunction);
+  ceres::GradientProblemSolver::Options options;
+  ceres::GradientProblemSolver::Summary summary;
+  ceres::Solve(options, problem, parameters, &summary);
+  EXPECT_NEAR(summary.final_cost, 0.0, std::numeric_limits<double>::epsilon());
+}
+
+}  // namespace internal
+}  // namespace ceres