Add simple unit tests for GradientProblem.

Change-Id: Id3b25a177aa92032f7f99b0a381c4f97d07d73b2

internal/ceres/CMakeLists.txt

diff --git a/internal/ceres/CMakeLists.txt b/internal/ceres/CMakeLists.txt
index a06f3a5..3108634 100644
--- a/internal/ceres/CMakeLists.txt
+++ b/internal/ceres/CMakeLists.txt
@@ -262,6 +262,7 @@
   CERES_TEST(evaluator)
   CERES_TEST(gradient_checker)
   CERES_TEST(gradient_checking_cost_function)
+  CERES_TEST(gradient_problem)
   CERES_TEST(graph)
   CERES_TEST(graph_algorithms)
   CERES_TEST(householder_vector)

internal/ceres/gradient_problem_test.cc

diff --git a/internal/ceres/gradient_problem_test.cc b/internal/ceres/gradient_problem_test.cc
new file mode 100644
index 0000000..b352577
--- /dev/null
+++ b/internal/ceres/gradient_problem_test.cc
@@ -0,0 +1,111 @@
+// Ceres Solver - A fast non-linear least squares minimizer
+// Copyright 2015 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: strandmark@google.com (Petter Strandmark)
+
+#include "ceres/gradient_problem.h"
+
+#include "gtest/gtest.h"
+
+namespace ceres {
+namespace internal {
+
+class QuadraticTestFunction : public ceres::FirstOrderFunction {
+ public:
+  explicit QuadraticTestFunction(bool* flag_to_set_on_destruction = NULL)
+      : flag_to_set_on_destruction_(flag_to_set_on_destruction) {}
+
+  virtual ~QuadraticTestFunction() {
+    if (flag_to_set_on_destruction_) {
+      *flag_to_set_on_destruction_ = true;
+    }
+  }
+
+  virtual bool Evaluate(const double* parameters,
+                        double* cost,
+                        double* gradient) const {
+    const double x = parameters[0];
+    cost[0] = x * x;
+    if (gradient != NULL) {
+      gradient[0] = 2.0 * x;
+    }
+    return true;
+  }
+
+  virtual int NumParameters() const { return 1; }
+
+ private:
+  bool* flag_to_set_on_destruction_;
+};
+
+TEST(GradientProblem, TakesOwnershipOfFirstOrderFunction) {
+  bool is_destructed = false;
+  {
+    ceres::GradientProblem problem(new QuadraticTestFunction(&is_destructed));
+  }
+  EXPECT_TRUE(is_destructed);
+}
+
+TEST(GradientProblem, EvaluationWithoutParameterizationOrGradient) {
+  ceres::GradientProblem problem(new QuadraticTestFunction());
+  double x = 7.0;
+  double cost = 0;
+  problem.Evaluate(&x, &cost, NULL);
+  EXPECT_EQ(x * x, cost);
+}
+
+TEST(GradientProblem, EvalutaionWithParameterizationAndNoGradient) {
+  ceres::GradientProblem problem(new QuadraticTestFunction(),
+                                 new IdentityParameterization(1));
+  double x = 7.0;
+  double cost = 0;
+  problem.Evaluate(&x, &cost, NULL);
+  EXPECT_EQ(x * x, cost);
+}
+
+TEST(GradientProblem, EvaluationWithoutParameterizationAndWithGradient) {
+  ceres::GradientProblem problem(new QuadraticTestFunction());
+  double x = 7.0;
+  double cost = 0;
+  double gradient = 0;
+  problem.Evaluate(&x, &cost, &gradient);
+  EXPECT_EQ(2.0 * x, gradient);
+}
+
+TEST(GradientProblem, EvaluationWithParameterizationAndWithGradient) {
+  ceres::GradientProblem problem(new QuadraticTestFunction(),
+                                 new IdentityParameterization(1));
+  double x = 7.0;
+  double cost = 0;
+  double gradient = 0;
+  problem.Evaluate(&x, &cost, &gradient);
+  EXPECT_EQ(2.0 * x, gradient);
+}
+
+}  // namespace internal
+}  // namespace ceres