diff --git a/src/mlpack/methods/gmm/gmm_train_main.cpp b/src/mlpack/methods/gmm/gmm_train_main.cpp
index 8bc64cddcf..2185dcf1de 100644
--- a/src/mlpack/methods/gmm/gmm_train_main.cpp
+++ b/src/mlpack/methods/gmm/gmm_train_main.cpp
@@ -145,12 +145,18 @@ static void mlpackMain()
       "number of Gaussians must be positive");
   const int gaussians = CLI::GetParam<int>("gaussians");
 
+  RequireParamValue<int>("trials", [](int x) { return x > 0; }, true,
+      "trials must be greater than 0");
+
   ReportIgnoredParam({{ "diagonal_covariance", true }}, "no_force_positive");
   RequireAtLeastOnePassed({ "output_model" }, false, "no model will be saved");
 
   RequireParamValue<double>("noise", [](double x) { return x >= 0.0; }, true,
       "variance of noise must be greater than or equal to 0");
 
+  RequireParamValue<int>("max_iterations", [](int x) { return x >= 0; }, true,
+      "max_iterations must be greater than or equal to 0");
+
   arma::mat dataPoints = std::move(CLI::GetParam<arma::mat>("input"));
 
   // Do we need to add noise to the dataset?
diff --git a/src/mlpack/tests/CMakeLists.txt b/src/mlpack/tests/CMakeLists.txt
index 15056a6878..c6daa4457b 100644
--- a/src/mlpack/tests/CMakeLists.txt
+++ b/src/mlpack/tests/CMakeLists.txt
@@ -122,6 +122,9 @@ add_executable(mlpack_test
   main_tests/det_test.cpp
   main_tests/decision_tree_test.cpp
   main_tests/decision_stump_test.cpp
+  main_tests/gmm_generate_test.cpp
+  main_tests/gmm_probability_test.cpp
+  main_tests/gmm_train_test.cpp
   main_tests/fastmks_test.cpp
   main_tests/kde_test.cpp
   main_tests/linear_regression_test.cpp
@@ -186,7 +189,7 @@ set(parallel_tests
   "SVDIncrementalTest;SVDBatchTest;"
   "LocalCoordinateCodingTest;FeedForwardNetworkTest;SparseAutoencoderTest;"
   "GMMTest;CFTest;ConvolutionalNetworkTest;HMMTest;LARSTest;"
-  "LogisticRegressionTest;"
+  "LogisticRegressionTest;GmmTrainMainTest;"
   "LinearSVMTest")
 
 # Add tests to the testing framework
diff --git a/src/mlpack/tests/main_tests/gmm_generate_test.cpp b/src/mlpack/tests/main_tests/gmm_generate_test.cpp
new file mode 100644
index 0000000000..0063c17aeb
--- /dev/null
+++ b/src/mlpack/tests/main_tests/gmm_generate_test.cpp
@@ -0,0 +1,78 @@
+/**
+ * @file gmm_generate_test.cpp
+ * @author Yashwant Singh
+ *
+ * Test mlpackMain() of gmm_generate_main.cpp.
+ *
+ * mlpack is free software; you may redistribute it and/or modify it under the
+ * terms of the 3-clause BSD license.  You should have received a copy of the
+ * 3-clause BSD license along with mlpack.  If not, see
+ * http://www.opensource.org/licenses/BSD-3-Clause for more information.
+ */
+#define BINDING_TYPE BINDING_TYPE_TEST
+static const std::string testName = "GmmGenerate";
+
+#include <mlpack/core.hpp>
+#include <mlpack/core/util/mlpack_main.hpp>
+#include <mlpack/methods/gmm/gmm_generate_main.cpp>
+
+#include "test_helper.hpp"
+#include <boost/test/unit_test.hpp>
+#include "../test_tools.hpp"
+
+using namespace mlpack;
+
+struct GmmGenerateTestFixture
+{
+ public:
+  GmmGenerateTestFixture()
+  {
+    // Cache in the options for this program.
+    CLI::RestoreSettings(testName);
+  }
+
+  ~GmmGenerateTestFixture()
+  {
+    // Clear the settings.
+    CLI::ClearSettings();
+  }
+};
+
+BOOST_FIXTURE_TEST_SUITE(GmmGenerateMainTest, GmmGenerateTestFixture);
+
+// Checking that Samples must greater than 0.
+BOOST_AUTO_TEST_CASE(GmmGenerateSamplesTest)
+{
+  arma::mat inputData(5, 10, arma::fill::randu);
+
+  GMM gmm(1, 5);
+  gmm.Train(inputData, 5);
+
+  SetInputParam("input_model", &gmm);
+
+  Log::Fatal.ignoreInput = true;
+  SetInputParam("samples", 0); // Invalid
+  BOOST_REQUIRE_THROW(mlpackMain(), std::runtime_error);
+  Log::Fatal.ignoreInput = false;
+}
+
+// Checking dimensionality of output.
+BOOST_AUTO_TEST_CASE(GmmGenerateDimensionality)
+{
+  arma::mat inputData(5, 10, arma::fill::randu);
+
+  GMM gmm(1, 5);
+  gmm.Train(inputData, 5);
+  SetInputParam("input_model", &gmm);
+  SetInputParam("samples", (int) 10);
+
+  mlpackMain();
+
+  arma::mat output = std::move(CLI::GetParam<arma::mat>("output"));
+
+  BOOST_REQUIRE_EQUAL(output.n_rows, gmm.Dimensionality());
+  BOOST_REQUIRE_EQUAL(output.n_cols, (int) 10);
+}
+
+BOOST_AUTO_TEST_SUITE_END();
+
diff --git a/src/mlpack/tests/main_tests/gmm_probability_test.cpp b/src/mlpack/tests/main_tests/gmm_probability_test.cpp
new file mode 100644
index 0000000000..0282763aa4
--- /dev/null
+++ b/src/mlpack/tests/main_tests/gmm_probability_test.cpp
@@ -0,0 +1,72 @@
+/**
+ * @file gmm_probability_test.cpp
+ * @author Yashwant Singh
+ *
+ * Test mlpackMain() of gmm_probability_main.cpp.
+ *
+ * mlpack is free software; you may redistribute it and/or modify it under the
+ * terms of the 3-clause BSD license.  You should have received a copy of the
+ * 3-clause BSD license along with mlpack.  If not, see
+ * http://www.opensource.org/licenses/BSD-3-Clause for more information.
+ */
+
+#define BINDING_TYPE BINDING_TYPE_TEST
+
+static const std::string testName = "GmmProbability";
+
+#include <mlpack/core.hpp>
+#include <mlpack/core/util/mlpack_main.hpp>
+#include <mlpack/methods/gmm/gmm_probability_main.cpp>
+
+#include "test_helper.hpp"
+
+#include <boost/test/unit_test.hpp>
+
+
+using namespace mlpack;
+
+struct GmmProbabilityTestFixture
+{
+ public:
+  GmmProbabilityTestFixture()
+  {
+    // Cache in the options for this program.
+    CLI::RestoreSettings(testName);
+  }
+
+  ~GmmProbabilityTestFixture()
+  {
+    // Clear the settings.
+    CLI::ClearSettings();
+  }
+};
+
+void ResetGmmProbabilitySetting()
+{
+  CLI::ClearSettings();
+  CLI::RestoreSettings(testName);
+}
+
+BOOST_FIXTURE_TEST_SUITE(GmmProbabilityMainTest, GmmProbabilityTestFixture);
+
+// Checking the input and output dimensionality.
+BOOST_AUTO_TEST_CASE(GmmProbabilityDimensionality)
+{
+  arma::mat inputData(5, 10, arma::fill::randu);
+
+  GMM gmm(1, 5);
+  gmm.Train(std::move(inputData), 5);
+
+  arma::mat inputPoints(5, 5, arma::fill::randu);
+
+  SetInputParam("input", std::move(inputPoints));
+  SetInputParam("input_model", &gmm);
+
+  mlpackMain();
+
+  BOOST_REQUIRE_EQUAL(CLI::GetParam<arma::mat>("output").n_cols, 5);
+  BOOST_REQUIRE_EQUAL(CLI::GetParam<arma::mat>("output").n_rows, 1);
+}
+
+BOOST_AUTO_TEST_SUITE_END();
+
diff --git a/src/mlpack/tests/main_tests/gmm_train_test.cpp b/src/mlpack/tests/main_tests/gmm_train_test.cpp
new file mode 100644
index 0000000000..e049e8538e
--- /dev/null
+++ b/src/mlpack/tests/main_tests/gmm_train_test.cpp
@@ -0,0 +1,490 @@
+/**
+ * @file gmm_train_test.cpp
+ * @author Yashwant Singh
+ *
+ * Test mlpackMain() of gmm_train_main.cpp.
+ *
+ * mlpack is free software; you may redistribute it and/or modify it under the
+ * terms of the 3-clause BSD license.  You should have received a copy of the
+ * 3-clause BSD license along with mlpack.  If not, see
+ * http://www.opensource.org/licenses/BSD-3-Clause for more information.
+ */
+
+#include<string>
+
+#define BINDING_TYPE BINDING_TYPE_TEST
+static const std::string testName = "GmmTrain";
+
+#include <mlpack/core.hpp>
+#include <mlpack/core/util/mlpack_main.hpp>
+#include "test_helper.hpp"
+#include <mlpack/methods/gmm/gmm_train_main.cpp>
+
+#include <boost/test/unit_test.hpp>
+#include "../test_tools.hpp"
+
+using namespace mlpack;
+
+struct GmmTrainTestFixture
+{
+ public:
+  GmmTrainTestFixture()
+  {
+    // Cache in the options for this program.
+    CLI::RestoreSettings(testName);
+  }
+
+  ~GmmTrainTestFixture()
+  {
+    // Clear the settings.
+    bindings::tests::CleanMemory();
+    CLI::ClearSettings();
+  }
+};
+
+void ResetGmmTrainSetting()
+{
+  CLI::ClearSettings();
+  CLI::RestoreSettings(testName);
+}
+
+
+BOOST_FIXTURE_TEST_SUITE(GmmTrainMainTest, GmmTrainTestFixture);
+
+// To check if the gaussian is positive or not.
+BOOST_AUTO_TEST_CASE(GmmTrainValidGaussianTest)
+{
+  arma::mat inputData(5, 10, arma::fill::randu);
+
+  SetInputParam("input", std::move(inputData));
+  SetInputParam("gaussians", 0); // Invalid
+
+  Log::Fatal.ignoreInput = true;
+  BOOST_REQUIRE_THROW(mlpackMain(), std::runtime_error);
+  Log::Fatal.ignoreInput = false;
+}
+
+/**
+  * To check if the number of gaussians in the output model is same as
+  * that of input gaussian parameter or not.
+ **/
+BOOST_AUTO_TEST_CASE(GmmTrainOutputModelGaussianTest)
+{
+  arma::mat inputData(5, 10, arma::fill::randu);
+
+  SetInputParam("input", std::move(inputData));
+  SetInputParam("gaussians", (int) 2);
+  SetInputParam("trials", (int) 2);
+
+  mlpackMain();
+
+  GMM* gmm = CLI::GetParam<GMM*>("output_model");
+  BOOST_REQUIRE_EQUAL(gmm->Gaussians(), (int) 2);
+}
+
+// Max iterations must be positive.
+BOOST_AUTO_TEST_CASE(GmmTrainMaxIterationsTest)
+{
+  arma::mat inputData(5, 10, arma::fill::randu);
+
+  SetInputParam("input", std::move(inputData));
+  SetInputParam("gaussians", (int) 2);
+  SetInputParam("trials", (int) 1);
+  SetInputParam("max_iterations", (int)-1); // Invalid.
+
+  Log::Fatal.ignoreInput = true;
+  BOOST_REQUIRE_THROW(mlpackMain(), std::runtime_error);
+  Log::Fatal.ignoreInput = false;
+}
+
+// Ensure that Trials must be greater than 0.
+BOOST_AUTO_TEST_CASE(GmmTrainPositiveTrialsTest)
+{
+  arma::mat inputData(5, 10, arma::fill::randu);
+
+  SetInputParam("input", std::move(inputData));
+  SetInputParam("gaussians", (int) 2);
+  SetInputParam("trials", (int) 0); // Invalid.
+
+  Log::Fatal.ignoreInput = true;
+  BOOST_REQUIRE_THROW(mlpackMain(), std::runtime_error);
+  Log::Fatal.ignoreInput = false;
+}
+
+// Checking that percentage is between 0 and 1.
+BOOST_AUTO_TEST_CASE(RefinedStartPercentageTest)
+{
+  arma::mat inputData(5, 10, arma::fill::randu);
+
+  SetInputParam("input", std::move(inputData));
+  SetInputParam("refined_start", true);
+
+  Log::Fatal.ignoreInput = true;
+  SetInputParam("percentage", (double) 2.0); // Invalid
+  BOOST_REQUIRE_THROW(mlpackMain(), std::runtime_error);
+
+  SetInputParam("percentage", (double) -1.0); // Invalid
+  BOOST_REQUIRE_THROW(mlpackMain(), std::runtime_error);
+
+  Log::Fatal.ignoreInput = false;
+}
+
+// Samplings must be positive.
+BOOST_AUTO_TEST_CASE(GmmTrainSamplings)
+{
+  arma::mat inputData(5, 10, arma::fill::randu);
+
+  SetInputParam("input", std::move(inputData));
+  SetInputParam("refined_start", true);
+  SetInputParam("samplings", (int) 0); // Invalid
+
+  Log::Fatal.ignoreInput = true;
+  BOOST_REQUIRE_THROW(mlpackMain(), std::runtime_error);
+  Log::Fatal.ignoreInput = false;
+}
+
+// Number of gaussians in the model trained from input model.
+BOOST_AUTO_TEST_CASE(GmmTrainNumberOfGaussian)
+{
+  arma::mat inputData(5, 10, arma::fill::randu);
+
+  SetInputParam("input", inputData);
+  SetInputParam("gaussians", (int) 2);
+
+  mlpackMain();
+
+  GMM* gmm = CLI::GetParam<GMM*>("output_model");
+
+  SetInputParam("input_model", gmm);
+
+  CLI::GetSingleton().Parameters()["input"].wasPassed = false;
+
+  SetInputParam("input", std::move(inputData));
+
+  mlpackMain();
+
+  GMM* gmm1 = CLI::GetParam<GMM*>("output_model");
+
+  BOOST_REQUIRE_EQUAL(gmm1->Gaussians(), (int) 2);
+}
+
+// Making sure that enabling no_force_positive doesn't crash.
+BOOST_AUTO_TEST_CASE(GmmTrainNoForcePositiveTest)
+{
+  arma::mat inputData(5, 10, arma::fill::randu);
+
+  SetInputParam("input", inputData);
+  SetInputParam("gaussians", (int) 1);
+  SetInputParam("no_force_positive", true);
+
+  mlpackMain();
+
+  GMM* gmm = CLI::GetParam<GMM*>("output_model");
+
+  SetInputParam("input_model", gmm);
+
+  CLI::GetSingleton().Parameters()["input"].wasPassed = false;
+
+  SetInputParam("input", std::move(inputData));
+
+  mlpackMain();
+
+  GMM* gmm1 = CLI::GetParam<GMM*>("output_model");
+
+  BOOST_REQUIRE_EQUAL(gmm1->Gaussians(), (int) 1);
+}
+
+// Ensure that Noise affects the final result.
+BOOST_AUTO_TEST_CASE(GmmTrainNoiseTest)
+{
+  arma::mat inputData;
+  if (!data::Load("data_3d_mixed.txt", inputData))
+    BOOST_FAIL("Unable to load train dataset data_3d_mixed.txt!");
+
+  SetInputParam("input", inputData);
+  SetInputParam("gaussians", (int) 2);
+  SetInputParam("noise", (double) 0.0);
+
+  size_t seed = std::time(NULL);
+  mlpack::math::randGen.seed((uint32_t) seed);
+  srand((unsigned int) seed);
+  arma::arma_rng::set_seed(seed);
+
+  mlpackMain();
+
+  GMM* gmm = CLI::GetParam<GMM*>("output_model");
+
+  ResetGmmTrainSetting();
+
+  SetInputParam("input", std::move(inputData));
+  SetInputParam("gaussians", (int) 2);
+  SetInputParam("noise", (double) 100.0);
+
+  mlpack::math::randGen.seed((uint32_t) seed);
+  srand((unsigned int) seed);
+  arma::arma_rng::set_seed(seed);
+
+  mlpackMain();
+
+  GMM* gmm1 = CLI::GetParam<GMM*>("output_model");
+
+  arma::uvec sortedIndices = sort_index(gmm->Weights());
+
+  for (size_t k = 0; k < sortedIndices.n_elem; k++)
+  {
+    BOOST_REQUIRE(arma::norm(gmm->Component(sortedIndices[k]).Mean() -
+                      gmm1->Component(sortedIndices[k]).Mean()) > 1e-50 ||
+                  arma::norm(gmm->Component(sortedIndices[k]).Covariance() -
+                      gmm1->Component(sortedIndices[k]).Covariance()) > 1e-50);
+  }
+}
+
+// Ensure that Trials affects the final result.
+BOOST_AUTO_TEST_CASE(GmmTrainTrialsTest)
+{
+  arma::mat inputData(5, 250, arma::fill::randu);
+
+  SetInputParam("input", inputData);
+  SetInputParam("gaussians", (int) 3);
+  SetInputParam("trials", (int) 1);
+  SetInputParam("max_iterations", (int) 500);
+
+  size_t seed = std::time(NULL);
+  mlpack::math::randGen.seed((uint32_t) seed);
+  srand((unsigned int) seed);
+  arma::arma_rng::set_seed(seed);
+
+  mlpackMain();
+
+  GMM* gmm = CLI::GetParam<GMM*>("output_model");
+
+  ResetGmmTrainSetting();
+
+  SetInputParam("input", std::move(inputData));
+  SetInputParam("gaussians", (int) 3);
+  SetInputParam("max_iterations", (int) 500);
+  SetInputParam("trials", (int) 500);
+
+  mlpack::math::randGen.seed((uint32_t) seed);
+  srand((unsigned int) seed);
+  arma::arma_rng::set_seed(seed);
+
+  mlpackMain();
+
+  GMM* gmm1 = CLI::GetParam<GMM*>("output_model");
+
+  arma::uvec sortedIndices = sort_index(gmm->Weights());
+
+  for (size_t k = 0; k < sortedIndices.n_elem; k++)
+  {
+    BOOST_REQUIRE(arma::norm(gmm->Component(sortedIndices[k]).Mean() -
+                      gmm1->Component(sortedIndices[k]).Mean()) > 1e-50 ||
+                  arma::norm(gmm->Component(sortedIndices[k]).Covariance() -
+                      gmm1->Component(sortedIndices[k]).Covariance()) > 1e-50);
+  }
+}
+
+// Ensure that Percentage affects the final result when refined_start is true.
+BOOST_AUTO_TEST_CASE(GmmTrainPercentageTest)
+{
+  arma::mat inputData;
+  if (!data::Load("data_3d_mixed.txt", inputData))
+    BOOST_FAIL("Unable to load train dataset data_3d_mixed.txt!");
+
+  SetInputParam("input", inputData);
+  SetInputParam("gaussians", (int) 2);
+  SetInputParam("refined_start", true);
+  SetInputParam("percentage", (double) 0.01);
+  SetInputParam("samplings", (int) 1000);
+
+  size_t seed = std::time(NULL);
+  mlpack::math::randGen.seed((uint32_t) seed);
+  srand((unsigned int) seed);
+  arma::arma_rng::set_seed(seed);
+
+  mlpackMain();
+
+  GMM* gmm = CLI::GetParam<GMM*>("output_model");
+
+  ResetGmmTrainSetting();
+
+  SetInputParam("input", std::move(inputData));
+  SetInputParam("gaussians", (int) 2);
+  SetInputParam("refined_start", true);
+  SetInputParam("percentage", (double) 0.45);
+  SetInputParam("samplings", (int) 1000);
+
+  mlpack::math::randGen.seed((uint32_t) seed);
+  srand((unsigned int) seed);
+  arma::arma_rng::set_seed(seed);
+
+  mlpackMain();
+
+  GMM* gmm1 = CLI::GetParam<GMM*>("output_model");
+
+  arma::uvec sortedIndices = sort_index(gmm->Weights());
+
+  for (size_t k = 0; k < sortedIndices.n_elem; k++)
+  {
+    BOOST_REQUIRE(arma::norm(gmm->Component(sortedIndices[k]).Mean() -
+                      gmm1->Component(sortedIndices[k]).Mean()) > 1e-50 ||
+                  arma::norm(gmm->Component(sortedIndices[k]).Covariance() -
+                      gmm1->Component(sortedIndices[k]).Covariance()) > 1e-50);
+  }
+}
+
+// Ensure that Sampling affects the final result when refined_start is true.
+BOOST_AUTO_TEST_CASE(GmmTrainSamplingsTest)
+{
+  arma::mat inputData;
+  if (!data::Load("data_3d_mixed.txt", inputData))
+    BOOST_FAIL("Unable to load train dataset data_3d_mixed.txt!");
+
+  SetInputParam("input", inputData);
+  SetInputParam("gaussians", (int) 8);
+  SetInputParam("refined_start", true);
+  SetInputParam("trials", (int) 2);
+  SetInputParam("samplings", (int) 10);
+
+  size_t seed = std::time(NULL);
+  mlpack::math::randGen.seed((uint32_t) seed);
+  srand((unsigned int) seed);
+  arma::arma_rng::set_seed(seed);
+
+  mlpackMain();
+
+  GMM* gmm = CLI::GetParam<GMM*>("output_model");
+
+  ResetGmmTrainSetting();
+
+  SetInputParam("input", std::move(inputData));
+  SetInputParam("gaussians", (int) 8);
+  SetInputParam("refined_start", true);
+  SetInputParam("trials", (int) 2);
+  SetInputParam("samplings", (int) 5000);
+
+  mlpack::math::randGen.seed((uint32_t) seed);
+  srand((unsigned int) seed);
+  arma::arma_rng::set_seed(seed);
+
+  mlpackMain();
+
+  GMM* gmm1 = CLI::GetParam<GMM*>("output_model");
+
+  arma::uvec sortedIndices = sort_index(gmm->Weights());
+
+  for (size_t k = 0; k < sortedIndices.n_elem; k++)
+  {
+    BOOST_REQUIRE(arma::norm(gmm->Component(sortedIndices[k]).Mean() -
+                      gmm1->Component(sortedIndices[k]).Mean()) > 1e-50 ||
+                  arma::norm(gmm->Component(sortedIndices[k]).Covariance() -
+                      gmm1->Component(sortedIndices[k]).Covariance()) > 1e-50);
+  }
+}
+
+// Ensure that tolerance affects the final result.
+BOOST_AUTO_TEST_CASE(GmmTrainToleranceTest)
+{
+  arma::mat inputData;
+  if (!data::Load("data_3d_mixed.txt", inputData))
+    BOOST_FAIL("Unable to load train dataset data_3d_mixed.txt!");
+
+  SetInputParam("input", inputData);
+  SetInputParam("gaussians", (int) 2);
+  SetInputParam("tolerance", (double) 1e-8);
+
+  size_t seed = std::time(NULL);
+  mlpack::math::randGen.seed((uint32_t) seed);
+  srand((unsigned int) seed);
+  arma::arma_rng::set_seed(seed);
+
+  mlpackMain();
+
+  GMM* gmm = CLI::GetParam<GMM*>("output_model");
+
+  ResetGmmTrainSetting();
+
+  SetInputParam("input", std::move(inputData));
+  SetInputParam("gaussians", (int) 2);
+  SetInputParam("tolerance", (double) 10);
+
+  mlpack::math::randGen.seed((uint32_t) seed);
+  srand((unsigned int) seed);
+  arma::arma_rng::set_seed(seed);
+
+  mlpackMain();
+
+  GMM* gmm1 = CLI::GetParam<GMM*>("output_model");
+
+  arma::uvec sortedIndices = sort_index(gmm->Weights());
+
+  for (size_t k = 0; k < sortedIndices.n_elem; k++)
+  {
+    BOOST_REQUIRE(arma::norm(gmm->Component(sortedIndices[k]).Mean() -
+                      gmm1->Component(sortedIndices[k]).Mean()) > 1e-50 ||
+                  arma::norm(gmm->Component(sortedIndices[k]).Covariance() -
+                      gmm1->Component(sortedIndices[k]).Covariance()) > 1e-50);
+  }
+}
+
+// Ensure that saved model can be used again.
+BOOST_AUTO_TEST_CASE(GmmTrainModelReuseTest)
+{
+  arma::mat inputData(5, 10, arma::fill::randu);
+
+  SetInputParam("input", inputData);
+  SetInputParam("gaussians", (int) 2);
+
+  mlpackMain();
+
+  GMM* gmm = CLI::GetParam<GMM*>("output_model");
+
+  SetInputParam("input_model", gmm);
+
+  CLI::GetSingleton().Parameters()["input"].wasPassed = false;
+
+  SetInputParam("input", inputData);
+
+  mlpackMain();
+
+  GMM* gmm1 = CLI::GetParam<GMM*>("output_model");
+
+  SetInputParam("input_model", gmm1);
+
+  CLI::GetSingleton().Parameters()["input"].wasPassed = false;
+
+  SetInputParam("input", std::move(inputData));
+
+  mlpackMain();
+
+  GMM* gmm2 = CLI::GetParam<GMM*>("output_model");
+
+  BOOST_REQUIRE_EQUAL(gmm1, gmm2);
+}
+
+// Ensure that Gmm's covariances are diagonal when diagonal_covariance is true.
+BOOST_AUTO_TEST_CASE(GmmTrainDiagCovariance)
+{
+  arma::mat inputData(5, 10, arma::fill::randu);
+
+  SetInputParam("input", std::move(inputData));
+  SetInputParam("gaussians", (int) 2);
+  SetInputParam("diagonal_covariance", true);
+
+  mlpackMain();
+
+  GMM* gmm = CLI::GetParam<GMM*>("output_model");
+
+  arma::uvec sortedIndices = sort_index(gmm->Weights());
+
+  for (size_t k = 0; k < sortedIndices.n_elem; k++)
+  {
+    arma::mat diagCov(gmm->Component(sortedIndices[k]).Covariance());
+      for (size_t i = 0; i < diagCov.n_rows; i++)
+        for (size_t j = 0; j < diagCov.n_cols; j++)
+          if (i != j && diagCov(i, j) != (double) 0)
+            BOOST_FAIL("Covariance Are Not Diagonal");
+  }
+}
+
+BOOST_AUTO_TEST_SUITE_END();