diff --git a/test/tests/Tmeta.cpp b/test/tests/Tmeta.cpp
new file mode 100644
index 0000000..3be6621
--- /dev/null
+++ b/test/tests/Tmeta.cpp
@@ -0,0 +1,174 @@
+/*!
+ * \file Tmeta.cpp
+ *
+ * Copyright (C) 2018 Christos Choutouridis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#include <utl/meta/meta.h>
+#include <gtest/gtest.h>
+#include <type_traits>
+
+namespace test_meta {
+   using namespace utl;
+   using namespace meta;
+
+   /*
+    * Test integral constant
+    */
+   // Test type_of fixture
+   template<class T> struct TestTypeOf {
+      using type = T;
+   };
+   TEST(Tmeta_integral, Integreal_type_) {
+      EXPECT_EQ(true, (std::is_same<int, type_<TestTypeOf<int>>>::value));
+   }
+   TEST(Tmeta_integral, IntegrealConstant) {
+      EXPECT_EQ(true, (std::is_same<int, integral_constant<int, 42>::value_type>::value));
+      EXPECT_EQ(true, (std::is_same<int, integral_constant<int, 42>::type::value_type>::value));
+      EXPECT_EQ(42, (integral_constant<int, 0>::value_type(42)));
+      EXPECT_EQ(42, (integral_constant<int, 42>()));
+   }
+   TEST(Tmeta_integral, BasicTypes) {
+      EXPECT_EQ(true, (std::is_same<bool, bool_<false>::value_type>::value));
+      EXPECT_EQ(true, bool_<true>::value);
+      EXPECT_EQ(true, (std::is_same<bool, false_::value_type>::value));
+      EXPECT_EQ(false, false_::value);
+      EXPECT_EQ(true, (std::is_same<bool, true_::value_type>::value));
+      EXPECT_EQ(true, true_::value);
+      EXPECT_EQ(true, (std::is_same<int, int_<0>::value_type>::value));
+      EXPECT_EQ(42, int_<42>::value);
+
+      EXPECT_EQ(true, (std::is_same<index_t, index_t_<0>::value_type>::value));
+      EXPECT_EQ(42U, index_t_<42U>::value);
+      EXPECT_EQ(true, (std::is_same<size_t, size_t_<0>::value_type>::value));
+      EXPECT_EQ(42U, size_t_<42U>::value);
+
+      EXPECT_EQ(sizeof(int), sizeof_<int>::value);
+      EXPECT_EQ(alignof(int), alignof_<int>::value);
+      EXPECT_EQ(static_cast<index_t>(-1), Npos::value);
+   }
+   /*
+    * Test integral constant arithmetic operations
+    */
+   TEST(Tmeta_integral, ArithmeticOperations) {
+      EXPECT_EQ (int_<42>(), inc<int_<41>>());
+      EXPECT_EQ (int_<42>(), dec<int_<43>>());
+      EXPECT_EQ (int_<42>(), (add<int_<23>, add<int_<17>, int_<2>>>()));
+      EXPECT_EQ (int_<42>(), (sub<int_<108>, int_<66>>()));
+      EXPECT_EQ (int_<42>(), (mult<int_<7>, mult<int_<3>, int_<2>>>()));
+      EXPECT_EQ (int_<42>(), (divide<int_<210>, int_<5>>()));
+      EXPECT_EQ (int_<42>(), negate<int_<-42>>());
+      EXPECT_EQ (int_< 1>(), (modulo<int_<43>, int_<42>>()));
+   }
+
+   /*
+    * Test logical
+    */
+   TEST(Tmeta_logical, ComparisonOperations) {
+      EXPECT_EQ (true, (std::is_same<bool_<true>, not_c<false>>::value));
+      EXPECT_EQ (true, (comp_eq<int_<7>, int_<7>>()));
+      EXPECT_EQ (true, (comp_ne<int_<42>, int_<7>>()));
+      EXPECT_EQ (true, (comp_lt<int_<42>, int_<43>>()));
+      EXPECT_EQ (true, (comp_gt<int_<43>, int_<42>>()));
+      EXPECT_EQ (true, (comp_le<int_<42>, int_<42>>()));
+      EXPECT_EQ (true, (comp_ge<int_<42>, int_<42>>()));
+   }
+
+   TEST(Tmeta_logical, BitOperations) {
+      EXPECT_EQ (0x00, (bitand_<int_<0x55>, int_<0xAA>>()));
+      EXPECT_EQ (0xFF, (bitor_<int_<0x55>, int_<0xAA>>()));
+      EXPECT_EQ (0xFA, (bitxor_<int_<0x55>, int_<0xAF>>()));
+      EXPECT_EQ (0x00, (bitnot_<int_<-1>>()));
+      //XXX: add shifts
+   }
+
+   TEST(Tmeta_logical, TypeOperations) {
+      struct Foo {};
+      struct Bar {};
+
+      EXPECT_EQ (true, (std::is_same<bool_<true>, not_<bool_<false>>>()));
+      EXPECT_EQ (true, (std::is_same<int_<42>, if_c<true, int_<42>, bool_<false>>>()));
+      EXPECT_EQ (true, (std::is_same<int_<42>, if_<bool_<true>, int_<42>, bool_<false>>>()));
+
+      EXPECT_EQ (true, (std::is_same<bool_<true>,  or_<bool_<true>,  bool_<false>>>()));
+      EXPECT_EQ (true, (std::is_same<bool_<false>, or_<bool_<false>, bool_<false>>>()));
+      EXPECT_EQ (true, (std::is_same<bool_<false>, and_<bool_<true>,  bool_<false>>>()));
+      EXPECT_EQ (true, (std::is_same<bool_<true>,  and_<bool_<true>,  bool_<true>>>()));
+
+      EXPECT_EQ (true, (same_<Foo, Foo>()));
+      EXPECT_EQ (false, (same_<Foo, Bar>()));
+      EXPECT_EQ (true, (not_same_<Foo, Bar>()));
+   }
+
+   /*
+    * Test void
+    */
+   TEST(Tmeta_void, VoidType) {
+      struct Foo {};
+      struct Bar {};
+      EXPECT_EQ(true, (std::is_same<void, void_t<int, long, Foo, Bar>>()));
+   }
+   /*
+    * Test invoke
+    */
+   template<class T1, class T2> struct MetaFunction { using type = int; };
+   template<typename... Args>   struct MetaClass {using apply = int; };
+   TEST(Tmeta_invoke, Invoke) {
+      //EXPECT_EQ (true, (is_evaluable<MetaFunction, int .long>()));
+   }
+   /*
+    * Test typelist
+    */
+   template<class T1, class T2> struct F {};
+   TEST(Tmeta_typelist, List_fold) {
+      struct X1 {};
+      struct X2 {};
+      struct X3 {};
+      struct X4 {};
+      using Q = quote<F>;
+
+      EXPECT_EQ(true, (std::is_same<fold<typelist<>, void, Q>, void>()));
+      EXPECT_EQ(true, (std::is_same<fold<typelist<X1>, void, Q>, F<void, X1>>()));
+      EXPECT_EQ(true, (std::is_same<fold<typelist<X1, X2>, void, Q>, F<F<void, X1>, X2>>()));
+      EXPECT_EQ(true, (std::is_same<fold<typelist<X1, X2, X3>, void, Q>, F<F<F<void, X1>, X2>, X3>>()));
+      EXPECT_EQ(true, (std::is_same<fold<typelist<X1, X2, X3, X4>, void, Q>, F<F<F<F<void, X1>, X2>, X3>, X4>>()));
+
+      //EXPECT_EQ(true, (std::is_same<rev_fold<typelist<>, void, Q>, void>()));
+      EXPECT_EQ(true, (std::is_same<rev_fold<typelist<X1>, void, Q>, F<X1, void>>()));
+      EXPECT_EQ(true, (std::is_same<rev_fold<typelist<X1, X2>, void, Q>, F<X1, F<X2, void>>>()));
+      EXPECT_EQ(true, (std::is_same<rev_fold<typelist<X1, X2, X3>, void, Q>, F<X1, F<X2, F<X3, void>>>>()));
+      EXPECT_EQ(true, (std::is_same<rev_fold<typelist<X1, X2, X3, X4>, void, Q>, F<X1, F<X2, F<X3, F<X4, void>>>>>()));
+   }
+   TEST(Tmeta_typelist, ListOperations) {
+      using l1 = typelist<int, short, long>;
+      using l2 = typelist<>;
+      using l3 = typelist<float, double, long double>;
+      using l4 = typelist<void*, char*>;
+      using conc = typelist<int, short, long, float, double, long double, void*, char*>;
+      using rep = typelist<int, int, int>;
+
+      EXPECT_EQ(3, size<l1>());
+      EXPECT_EQ(true, empty<l2>());
+
+      EXPECT_EQ(true, (std::is_same<conc, concat<l1, l2, l3, l4>>()));
+      EXPECT_EQ(true, (std::is_same<rep, repeat_n<int_<3>, int>>()));
+      EXPECT_EQ(true, (std::is_same<int, front<l1>>()));
+      EXPECT_EQ(true, (std::is_same<long, back<l1>>()));
+      EXPECT_EQ(true, (std::is_same<double, at<l3, int_<1>>>()));
+
+      EXPECT_EQ(true, (std::is_same<typelist<short, long>, pop_front<l1>>()));
+   }
+}
diff --git a/test/tests/test_ostream_dev.cpp b/test/tests/test_ostream_dev.cpp
new file mode 100644
index 0000000..da9c27a
--- /dev/null
+++ b/test/tests/test_ostream_dev.cpp
@@ -0,0 +1,257 @@
+/*!
+ * \file test_ostream_dev.cpp
+ *
+ * Copyright (C) 2018 Christos Choutouridis
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 3
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <gtest/gtest.h>
+#include <utl/dev/ostream_dev.h>
+#include <array>
+
+namespace test_ostream_dev {
+   using namespace utl;
+
+   // Device base data types
+   // MUST be DefaultConstructible, Copyable
+   using test_data_t = uint8_t;
+
+   // Test data
+   static const size_t SIZE = 10;
+
+   test_data_t     Idata = 42;
+   test_data_t&   IdataR = Idata;
+   test_data_t&& IdataRR = 0xAA;
+   test_data_t Ibuffer[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
+
+   // ostream device implementer (Mocks)
+   class Ostream_dev_impl : public ostream_dev<Ostream_dev_impl, test_data_t> {
+      friend ostream_dev<Ostream_dev_impl, test_data_t>;
+   public:
+      // virtual device
+      static constexpr size_t N =SIZE;
+      std::array<test_data_t, N> v {};  // more than one so we can remember N-1 previous values
+      size_t c {0};
+
+   protected:
+      // ostream_dev requirements
+      size_t put_ (const test_data_t& data) {
+         v[c++] = data;
+         if (c >= N)
+            c = 0;
+         return 1;
+      }
+      size_t put_ (const test_data_t* data, size_t n) {
+         for (size_t i=0 ; i<n && i<N; ++i) {
+            v[i] = data[i];
+         }
+         return n;
+      }
+   public:
+      test_data_t& getLastV () { return (c) ? v[c-1] : v[N-1]; }
+   };
+   // virtual ostream device
+   class Ostream_vdev_impl : public ostream_dev<virtual_tag, test_data_t> {
+   public:
+      // virtual device
+      static constexpr size_t N =SIZE;
+      std::array<test_data_t, N> v {};
+      size_t c {0};
+
+   protected:
+      // ostream_dev requirements
+      size_t put_ (const test_data_t& data) {
+         v[c++] = data;
+         if (c >= N)
+            c = 0;
+         return 1;
+      }
+      size_t put_ (const test_data_t* data, size_t n) {
+         for (size_t i=0 ; i<n && i<N; ++i) {
+            v[i] = data[i];
+         }
+         return n;
+      }
+   public:
+      test_data_t& getLastV () { return (c) ? v[c-1] : v[N-1]; }
+   };
+
+   // fixtures
+   class Tostream_Idev : public ::testing::Test {
+   protected:
+      // zero initialized device
+      Ostream_dev_impl osIdev {};
+   };
+   class Tostream_Vdev : public ::testing::Test {
+   protected:
+      // zero initialized devices
+      std::array<Ostream_vdev_impl, 5> osVdev {};
+      ostream_dev<virtual_tag, test_data_t> *basePointer = nullptr;
+   };
+
+   //ToDo: Must add Concept test for ostream_dev
+//   TEST_F(Tostream_Idev, TestConcept) {
+//      EXPECT_EQ(true, Ostream_dev<osIdev>);
+//   }
+
+   TEST_F(Tostream_Idev, Construction) {
+      EXPECT_LT(0UL, sizeof(osIdev));
+   }
+
+   TEST_F (Tostream_Idev, Api) {
+      EXPECT_EQ(1UL, osIdev.put(Idata)); // single write from var
+      EXPECT_EQ(Idata, osIdev.getLastV ());
+
+      EXPECT_EQ(1UL, osIdev.put(IdataR));// single write from lvalue ref
+      EXPECT_EQ(IdataR, osIdev.getLastV ());
+
+      EXPECT_EQ(1UL, osIdev.put(IdataRR));// single write from rvalue ref
+      EXPECT_EQ(IdataRR, osIdev.getLastV ());
+
+      EXPECT_EQ(1UL, osIdev.put(42));// single write from rvalue
+      EXPECT_EQ(42U, osIdev.getLastV ());
+
+      EXPECT_EQ(7U, osIdev.put(Ibuffer, 7)); // batch write some data
+      for (size_t i =0 ; i<7 ; ++i) {
+         EXPECT_EQ(Ibuffer[i], osIdev.v[i]);
+      }
+      EXPECT_EQ(0, osIdev.v[7]);
+
+      EXPECT_EQ(SIZE, osIdev.put(Ibuffer, SIZE));   // batch write all data
+      for (size_t i =0 ; i<SIZE ; ++i) {
+         EXPECT_EQ(Ibuffer[i], osIdev.v[i]);
+      }
+   }
+
+   TEST_F (Tostream_Idev, streamOperator) {
+      struct Blop {
+         test_data_t x, y, z;
+      };
+
+      osIdev << Idata; // single write from var
+      EXPECT_EQ(Idata, osIdev.getLastV ());
+
+      osIdev << IdataR;// single write from lvalue ref
+      EXPECT_EQ(IdataR, osIdev.getLastV ());
+
+      osIdev << IdataRR;// single write from rvalue ref
+      EXPECT_EQ(IdataRR, osIdev.getLastV ());
+
+      osIdev << (test_data_t)42;  // single write from rvalue
+      EXPECT_EQ(42U, osIdev.getLastV ());
+
+      // stream a blop of data (should use put(T*, N) version)
+      Blop blop {1, 1, 42};
+      osIdev << blop;
+      EXPECT_EQ(1U, osIdev.v[0]);
+      EXPECT_EQ(1U, osIdev.v[1]);
+      EXPECT_EQ(42U, osIdev.v[2]);
+
+      const Blop cblop {2, 2, 42};
+      osIdev << cblop;
+      EXPECT_EQ(2U, osIdev.v[0]);
+      EXPECT_EQ(2U, osIdev.v[1]);
+      EXPECT_EQ(42U, osIdev.v[2]);
+   }
+
+   TEST_F (Tostream_Idev, Iterator1) {
+      // default constructible
+      Ostream_dev_impl::iterator def_it;
+      EXPECT_EQ (0, *(int32_t*)&def_it);  // not dereferencable
+
+      // output iterator requirements
+      // https://en.cppreference.com/w/cpp/named_req/OutputIterator
+      auto it = osIdev.begin();
+      auto it2(it);
+      EXPECT_EQ (*(int32_t*)&it, *(int32_t*)&it2);
+
+      it2 = it;
+      EXPECT_EQ (*(int32_t*)&it, *(int32_t*)&it2);
+      def_it = it;
+      EXPECT_EQ (*(int32_t*)&it, *(int32_t*)&def_it);
+      ++it, it++;
+
+      *it = Idata;
+      EXPECT_EQ (Idata, osIdev.getLastV ());
+      *it = IdataR;
+      EXPECT_EQ (IdataR, osIdev.getLastV ());
+      *it = IdataRR;
+      EXPECT_EQ (IdataRR, osIdev.getLastV ());
+
+      *it++ = Idata;
+      EXPECT_EQ (Idata, osIdev.getLastV ());
+
+   }
+
+   TEST_F (Tostream_Idev, Iterator2) {
+         auto it = osIdev.begin();
+
+         std::fill_n(it, SIZE, Idata);
+         for (size_t i=0 ;i<SIZE ; ++i) {
+            EXPECT_EQ (Idata, osIdev.v[i]);
+         }
+      }
+
+   TEST_F (Tostream_Vdev, virtualApi) {
+      // loop to virtual devices and use them via base pointer
+      for (auto& dev : osVdev) {
+         basePointer = &dev;
+         basePointer->put(Idata);
+         EXPECT_EQ(Idata, dev.v[0]);
+
+         EXPECT_EQ(SIZE, basePointer->put(Ibuffer, SIZE));   // batch write all data
+         for (size_t i =0 ; i<SIZE ; ++i) {
+            EXPECT_EQ(Ibuffer[i], dev.v[i]);
+         }
+      }
+   }
+
+   TEST_F (Tostream_Vdev, virtualStream) {
+         struct Blop {
+            test_data_t x, y, z;
+         };
+         Blop blop {1, 1, 42};
+         const Blop cblop {2, 2, 42};
+
+         // loop to virtual devices and use them via base pointer
+         for (auto& dev : osVdev) {
+            basePointer = &dev;
+            *basePointer << IdataR;
+            EXPECT_EQ(IdataR, dev.v[0]);
+
+            *basePointer << blop;
+            EXPECT_EQ(1U, dev.v[0]);
+            EXPECT_EQ(1U, dev.v[1]);
+            EXPECT_EQ(42U, dev.v[2]);
+
+            *basePointer << cblop;
+            EXPECT_EQ(2U, dev.v[0]);
+            EXPECT_EQ(2U, dev.v[1]);
+            EXPECT_EQ(42U, dev.v[2]);
+         }
+      }
+
+   TEST_F (Tostream_Vdev, virtualIterator) {
+         // loop to virtual devices and use them via base pointer
+         for (auto& dev : osVdev) {
+            basePointer = &dev;
+            auto it = *basePointer->begin();
+            std::fill_n(it, SIZE, Idata);
+            for (size_t i=0 ;i<SIZE ; ++i) {
+               EXPECT_EQ (Idata, dev.v[i]);
+            }
+         }
+      }
+}