diff --git a/fimdlp/CPPFImdlp.h b/fimdlp/CPPFImdlp.h
index a60a93a..d36f6f0 100644
--- a/fimdlp/CPPFImdlp.h
+++ b/fimdlp/CPPFImdlp.h
@@ -21,6 +21,8 @@ namespace mdlp
         std::vector<int> y;
         std::vector<float> xDiscretized;
         std::vector<CutPointBody> cutPoints;
+
+    protected:
         std::vector<size_t> sortIndices(std::vector<float> &);
 
     public:
diff --git a/fimdlp/test/CMakeLists.txt b/fimdlp/test/CMakeLists.txt
index 6177fbe..1fa0e3d 100644
--- a/fimdlp/test/CMakeLists.txt
+++ b/fimdlp/test/CMakeLists.txt
@@ -15,16 +15,13 @@ FetchContent_MakeAvailable(googletest)
 
 enable_testing()
 
-add_executable(
-  Metrics_unittest
-  ../Metrics.cpp
-  Metrics_unittest.cc
-)
-target_link_libraries(
-  Metrics_unittest
-  GTest::gtest_main
-)
+add_executable(Metrics_unittest ../Metrics.cpp Metrics_unittest.cc)
+add_executable(FImdlp_unittest ../CPPFImdlp.cpp ../Metrics.cpp FImdlp_unittest.cc)
+target_link_libraries(Metrics_unittest GTest::gtest_main)
+target_link_libraries(FImdlp_unittest GTest::gtest_main)
+
 
 include(GoogleTest)
 gtest_discover_tests(Metrics_unittest)
+gtest_discover_tests(FImdlp_unittest)
 
diff --git a/fimdlp/test/FImdlp_unittest.cc b/fimdlp/test/FImdlp_unittest.cc
new file mode 100644
index 0000000..a78fac3
--- /dev/null
+++ b/fimdlp/test/FImdlp_unittest.cc
@@ -0,0 +1,39 @@
+#include "gtest/gtest.h"
+#include "../CPPFImdlp.h"
+namespace
+{
+    float precision = 0.000001;
+    class TestMetrics : protected mdlp::CPPFImdlp
+    {
+    public:
+        std::vector<size_t> testSort(std::vector<float> &X)
+        {
+            return sortIndices(X);
+        }
+    };
+    void check_sorted_vector(std::vector<float> &X, std::vector<size_t> indices)
+    {
+        TestMetrics testClass = TestMetrics();
+        std::vector<size_t> testSortedIndices = testClass.testSort(X);
+        float prev = X[testSortedIndices[0]];
+        for (auto i = 0; i < X.size(); ++i)
+        {
+            EXPECT_EQ(testSortedIndices[i], indices[i]);
+            EXPECT_LE(prev, X[testSortedIndices[i]]);
+            prev = X[testSortedIndices[i]];
+        }
+    }
+    TEST(FImdlpTest, SortIndices)
+    {
+
+        std::vector<float> X = {5.7, 5.3, 5.2, 5.1, 5.0, 5.6, 5.1, 6.0, 5.1, 5.9};
+        std::vector<size_t> indices = {4, 3, 6, 8, 2, 1, 5, 0, 9, 7};
+        check_sorted_vector(X, indices);
+        X = {5.77, 5.88, 5.99};
+        indices = {0, 1, 2};
+        check_sorted_vector(X, indices);
+        X = {5.33, 5.22, 5.11};
+        indices = {2, 1, 0};
+        check_sorted_vector(X, indices);
+    }
+}
\ No newline at end of file
diff --git a/fimdlp/test/Metrics_unittest.cc b/fimdlp/test/Metrics_unittest.cc
index 7619577..3c25fe2 100644
--- a/fimdlp/test/Metrics_unittest.cc
+++ b/fimdlp/test/Metrics_unittest.cc
@@ -1,7 +1,10 @@
 #include "gtest/gtest.h"
 #include "../Metrics.h"
+
 namespace
 {
+
+    float precision = 0.000001;
     TEST(MetricTest, NumClasses)
     {
         std::vector<int> y = {1, 1, 1, 1, 1, 1, 1, 1, 2, 1};
@@ -17,7 +20,14 @@ namespace
         EXPECT_EQ(1, mdlp::Metrics::entropy(y, indices, 0, 10, 2));
         EXPECT_EQ(0, mdlp::Metrics::entropy(y, indices, 0, 5, 1));
         std::vector<int> yz = {1, 1, 1, 1, 1, 1, 1, 1, 2, 1};
-        ASSERT_NEAR(0.468996, mdlp::Metrics::entropy(yz, indices, 0, 10, 2), 0.000001);
+        ASSERT_NEAR(0.468996, mdlp::Metrics::entropy(yz, indices, 0, 10, 2), precision);
+    }
+    TEST(MetricTest, InformationGain)
+    {
+        std::vector<int> y = {1, 1, 1, 1, 1, 2, 2, 2, 2, 2};
+        std::vector<size_t> indices = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+        std::vector<int> yz = {1, 1, 1, 1, 1, 1, 1, 1, 2, 1};
+        ASSERT_NEAR(1, mdlp::Metrics::informationGain(y, indices, 0, 10, 5, 2), precision);
+        ASSERT_NEAR(0.108032, mdlp::Metrics::informationGain(yz, indices, 0, 10, 5, 2), precision);
     }
-
 }
\ No newline at end of file
diff --git a/fimdlp/test/test.sh b/fimdlp/test/test.sh
index f01c0de..7c0aa40 100755
--- a/fimdlp/test/test.sh
+++ b/fimdlp/test/test.sh
@@ -1,4 +1,12 @@
 cmake -S . -B build
+if test $? -ne 0; then
+   echo "Error in creating build commands."
+   exit 1
+fi
 cmake --build build
+if test $? -ne 0; then
+   echo "Error in build command."
+   exit 1
+fi
 cd build
 ctest --output-on-failure