diff --git a/src/tools/std20/concepts/test/CMakeLists.txt b/src/tools/std20/concepts/test/CMakeLists.txt
index 60a6341..1e459fc 100644
--- a/src/tools/std20/concepts/test/CMakeLists.txt
+++ b/src/tools/std20/concepts/test/CMakeLists.txt
@@ -7,6 +7,22 @@ add_cpp_test( std20.concepts.integral                  integral.test.cpp )
 add_cpp_test( std20.concepts.signed_integral           signed_integral.test.cpp )
 add_cpp_test( std20.concepts.unsigned_integral         unsigned_integral.test.cpp )
 add_cpp_test( std20.concepts.floating_point            floating_point.test.cpp )
-
+#add_cpp_test( std20.concepts.assignable_from           assignable_from.test.cpp )
+#add_cpp_test( std20.concepts.swappable                 swappable.test.cpp )
+add_cpp_test( std20.concepts.destructible              destructible.test.cpp )
+add_cpp_test( std20.concepts.constructible_from        constructible_from.test.cpp )
+add_cpp_test( std20.concepts.default_initializable     default_initializable.test.cpp )
+#add_cpp_test( std20.concepts.move_constructible        move_constructible.test.cpp )
+#add_cpp_test( std20.concepts.copy_constructible        copy_constructible.test.cpp )
 add_cpp_test( std20.concepts.equality_comparable       equality_comparable.test.cpp )
 add_cpp_test( std20.concepts.totally_ordered           totally_ordered.test.cpp )
+#add_cpp_test( std20.concepts.movable                   movable.test.cpp )
+#add_cpp_test( std20.concepts.copyable                  copyable.test.cpp )
+#add_cpp_test( std20.concepts.semiregular               semiregular.test.cpp )
+#add_cpp_test( std20.concepts.regular                   regular.test.cpp )
+#add_cpp_test( std20.concepts.invocable                 invocable.test.cpp )
+#add_cpp_test( std20.concepts.regular_invocable         regular_invocable.test.cpp )
+#add_cpp_test( std20.concepts.predicate                 predicate.test.cpp )
+#add_cpp_test( std20.concepts.relation                  relation.test.cpp )
+#add_cpp_test( std20.concepts.equivalence_relation      equivalence_relation.test.cpp )
+#add_cpp_test( std20.concepts.strict_weak_order         strict_weak_order.test.cpp )
diff --git a/src/tools/std20/concepts/test/constructible_from.test.cpp b/src/tools/std20/concepts/test/constructible_from.test.cpp
new file mode 100644
index 0000000..f4a6e59
--- /dev/null
+++ b/src/tools/std20/concepts/test/constructible_from.test.cpp
@@ -0,0 +1,93 @@
+// include Catch2
+#include <catch2/catch_test_macros.hpp>
+
+// what we are testing
+#include "tools/std20/concepts.hpp"
+
+// other includes
+#include <string>
+
+// convenience typedefs
+//using namespace njoy::tools;
+namespace std20 = nano::ranges;
+
+// test code
+struct Foo {
+
+  ~Foo() noexcept {};
+};
+
+struct NonDefaultConstructableFoo {
+
+  NonDefaultConstructableFoo() = delete;
+  ~NonDefaultConstructableFoo() noexcept {};
+};
+
+struct Bar {
+
+  Bar() = default;
+  explicit Bar( int );
+  ~Bar() = default;
+};
+
+SCENARIO( "constructible_from" ) {
+
+  CHECK( std20::constructible_from< Foo > );
+  CHECK( std20::constructible_from< Bar > );
+  CHECK( std20::constructible_from< std::string > );
+  CHECK( std20::constructible_from< Bar, int > );
+
+  CHECK( ! std20::constructible_from< NonDefaultConstructableFoo > );
+
+  CHECK( std20::constructible_from< int > );
+  CHECK( std20::constructible_from< const int > );
+  CHECK( ! std20::constructible_from< const int& > );
+  CHECK( ! std20::constructible_from< int() > );
+  CHECK( ! std20::constructible_from< int (&)() > );
+  CHECK( ! std20::constructible_from< int[] > );
+  CHECK( std20::constructible_from< int[2] > );
+  CHECK( std20::constructible_from< int const (&)[2], int (&)[2] > );
+  CHECK( ! std20::constructible_from< int, int (&)[2] >);
+
+  CHECK( std20::constructible_from< int, int > );
+  CHECK( std20::constructible_from< int, int& > );
+  CHECK( std20::constructible_from< int, int&& > );
+  CHECK( std20::constructible_from< int, const int > );
+  CHECK( std20::constructible_from< int, const int& > );
+  CHECK( std20::constructible_from< int, const int&& > );
+
+  CHECK( std20::constructible_from< Foo, Foo > );
+  CHECK( std20::constructible_from< Foo, Foo& > );
+  CHECK( std20::constructible_from< Foo, Foo&& > );
+  CHECK( std20::constructible_from< Foo, const Foo > );
+  CHECK( std20::constructible_from< Foo, const Foo& > );
+  CHECK( std20::constructible_from< Foo, const Foo&&> );
+
+  CHECK( ! std20::constructible_from< int&, int > );
+  CHECK( std20::constructible_from< int&, int& > );
+  CHECK( ! std20::constructible_from< int&, int&& > );
+  CHECK( ! std20::constructible_from< int&, const int > );
+  CHECK( ! std20::constructible_from< int&, const int& > );
+  CHECK( ! std20::constructible_from< int&, const int&& > );
+
+  CHECK( std20::constructible_from< const int&, int > );
+  CHECK( std20::constructible_from< const int&, int& > );
+  CHECK( std20::constructible_from< const int&, int&& > );
+  CHECK( std20::constructible_from< const int&, const int > );
+  CHECK( std20::constructible_from< const int&, const int& > );
+  CHECK( std20::constructible_from< const int&, const int&& > );
+
+  CHECK( std20::constructible_from< int&&, int > );
+  CHECK( ! std20::constructible_from< int&&, int& > );
+  CHECK( std20::constructible_from< int&&, int&& > );
+  CHECK( ! std20::constructible_from< int&&, const int > );
+  CHECK( ! std20::constructible_from< int&&, const int& > );
+  CHECK( ! std20::constructible_from< int&&, const int&& > );
+
+  CHECK( std20::constructible_from< const int&&, int > );
+  CHECK(! std20::constructible_from< const int&&, int& > );
+  CHECK( std20::constructible_from< const int&&, int&& > );
+  CHECK( std20::constructible_from< const int&&, const int > );
+  CHECK(! std20::constructible_from< const int&&, const int& > );
+  CHECK( std20::constructible_from< const int&&, const int&& > );
+} // SCENARIO
diff --git a/src/tools/std20/concepts/test/default_initializable.test.cpp b/src/tools/std20/concepts/test/default_initializable.test.cpp
new file mode 100644
index 0000000..bceb348
--- /dev/null
+++ b/src/tools/std20/concepts/test/default_initializable.test.cpp
@@ -0,0 +1,41 @@
+// include Catch2
+#include <catch2/catch_test_macros.hpp>
+
+// what we are testing
+#include "tools/std20/concepts.hpp"
+
+// other includes
+#include <string>
+
+// convenience typedefs
+//using namespace njoy::tools;
+namespace std20 = nano::ranges;
+
+// test code
+struct Foo {
+
+  ~Foo() noexcept {};
+};
+
+struct NonDefaultConstructableFoo {
+
+  NonDefaultConstructableFoo() = delete;
+  ~NonDefaultConstructableFoo() noexcept {};
+};
+
+SCENARIO( "default_initializable" ) {
+
+  CHECK( std20::default_initializable< Foo > );
+  CHECK( ! std20::default_initializable< NonDefaultConstructableFoo > );
+
+  CHECK( std20::default_initializable< int > );
+  CHECK( ! std20::default_initializable< const int > );
+  CHECK( ! std20::default_initializable< int& > );
+  CHECK( ! std20::default_initializable< int() > );
+  CHECK( ! std20::default_initializable< int (&)() > );
+  CHECK( std20::default_initializable< double > );
+  CHECK( ! std20::default_initializable< void > );
+  CHECK( ! std20::default_initializable< int[] > );
+  CHECK( std20::constructible_from< int[2] > );
+  CHECK( std20::default_initializable< int[2] > );
+} // SCENARIO
diff --git a/src/tools/std20/concepts/test/destructible.test.cpp b/src/tools/std20/concepts/test/destructible.test.cpp
new file mode 100644
index 0000000..7e89e2f
--- /dev/null
+++ b/src/tools/std20/concepts/test/destructible.test.cpp
@@ -0,0 +1,57 @@
+// include Catch2
+#include <catch2/catch_test_macros.hpp>
+
+// what we are testing
+#include "tools/std20/concepts.hpp"
+
+// other includes
+#include <string>
+
+// convenience typedefs
+//using namespace njoy::tools;
+namespace std20 = nano::ranges;
+
+// test code
+struct Foo {
+
+  ~Foo() noexcept {};
+};
+
+struct IndestructibleFoo {
+
+  ~IndestructibleFoo() = delete;
+};
+
+struct ThrowingDestructorFoo {
+
+  ~ThrowingDestructorFoo() noexcept(false);
+};
+
+struct Bar {
+
+  ~Bar() = default;
+};
+
+SCENARIO( "destructible" ) {
+
+  CHECK( std20::destructible< Foo > );
+  CHECK( std20::destructible< Bar > );
+  CHECK( std20::destructible< std::string > );
+
+  CHECK( ! std20::destructible< IndestructibleFoo > );
+  CHECK( ! std20::destructible< ThrowingDestructorFoo > );
+
+  CHECK( std20::destructible< int > );
+  CHECK( std20::destructible< const int > );
+
+  CHECK( std20::destructible< int& > );
+  CHECK( std20::destructible< void (*)() > );
+  CHECK( std20::destructible< void (&)() > );
+  CHECK( std20::destructible< int[2] > );
+  CHECK( std20::destructible< int (*)[2] > );
+  CHECK( std20::destructible< int (&)[2] > );
+
+  CHECK( ! std20::destructible< void > );
+  CHECK( ! std20::destructible< void() > );
+  CHECK( ! std20::destructible< int[] > );
+} // SCENARIO