diff --git a/tests/cpp/objective/test_regression_obj.cc b/tests/cpp/objective/test_regression_obj.cc
index 607055396..541f01f4f 100644
--- a/tests/cpp/objective/test_regression_obj.cc
+++ b/tests/cpp/objective/test_regression_obj.cc
@@ -65,3 +65,39 @@ TEST(Objective, LogisticRawGPair) {
                    { 0.5, 0.52, 0.71, 0.73, -0.5, -0.47, -0.28, -0.26},
                    {0.25, 0.24, 0.20, 0.19, 0.25,  0.24,  0.20,  0.19});
 }
+
+TEST(Objective, PoissonRegressionGPair) {
+  xgboost::ObjFunction * obj = xgboost::ObjFunction::Create("count:poisson");
+  std::vector<std::pair<std::string, std::string> > args;
+  args.push_back(std::make_pair("max_delta_step", "0.1"));
+  obj->Configure(args);
+  CheckObjFunction(obj,
+                   {   0,  0.1,  0.9,    1,    0,  0.1,  0.9,    1},
+                   {   0,    0,    0,    0,    1,    1,    1,    1},
+                   {   1,    1,    1,    1,    1,    1,    1,    1},
+                   {   1, 1.10, 2.45, 2.71,    0, 0.10, 1.45, 1.71},
+                   {1.10, 1.22, 2.71, 3.00, 1.10, 1.22, 2.71, 3.00});
+}
+
+TEST(Objective, PoissonRegressionBasic) {
+  xgboost::ObjFunction * obj = xgboost::ObjFunction::Create("count:poisson");
+  std::vector<std::pair<std::string, std::string> > args;
+  obj->Configure(args);
+
+  // test label validation
+  EXPECT_ANY_THROW(CheckObjFunction(obj, {0}, {-1}, {1}, {0}, {0}))
+    << "Expected error when label < 0 for PoissonRegression";
+
+  // test ProbToMargin
+  EXPECT_NEAR(obj->ProbToMargin(0.1), -2.30, 0.01);
+  EXPECT_NEAR(obj->ProbToMargin(0.5), -0.69, 0.01);
+  EXPECT_NEAR(obj->ProbToMargin(0.9), -0.10, 0.01);
+
+  // test PredTransform
+  std::vector<xgboost::bst_float> preds = {0, 0.1, 0.5, 0.9, 1};
+  std::vector<xgboost::bst_float> out_preds = {1, 1.10, 1.64, 2.45, 2.71};
+  obj->PredTransform(&preds);
+  for (int i = 0; i < preds.size(); ++i) {
+    EXPECT_NEAR(preds[i], out_preds[i], 0.01);
+  }
+}