diff --git a/include/indentlog/print/color.hpp b/include/indentlog/print/color.hpp
index 47167b66..f8b64985 100644
--- a/include/indentlog/print/color.hpp
+++ b/include/indentlog/print/color.hpp
@@ -14,6 +14,18 @@ namespace xo {
         rgb
     };
 
+    inline std::ostream &
+    operator<< (std::ostream & os, color_encoding x) {
+        switch(x) {
+        case color_encoding::none: os << "none"; break;
+        case color_encoding::ansi: os << "ansi"; break;
+        case color_encoding::xterm: os << "xterm"; break;
+        case color_encoding::rgb: os << "rgb"; break;
+        default: os << "???"; break;
+        }
+        return os;
+    } /*operator<<*/
+
     /* specify a color (consistent with ANSI escape sequences - the  Select Graphics Rendition subset
      * see [[https://stackoverflow.com/questions/4842424/list-of-ansi-color-escape-sequences]]
      *
@@ -106,6 +118,12 @@ namespace xo {
         std::uint32_t code_ = 0;
     }; /*color_spec_type*/
 
+    inline std::ostream &
+    operator<< (std::ostream & os, color_spec_type const & x) {
+        os << "<color_spec_type :encoding " << x.encoding() << " :code " << x.code() << ">";
+        return os;
+    } /*operator<<*/
+
     enum class coloring_control_flags : std::uint8_t {
         none = 0x0,
         color_on = 0x01,
diff --git a/include/indentlog/print/concat.hpp b/include/indentlog/print/concat.hpp
index 31bd6b43..223900ec 100644
--- a/include/indentlog/print/concat.hpp
+++ b/include/indentlog/print/concat.hpp
@@ -20,6 +20,11 @@ namespace xo {
         T2 x2_;
     }; /*concat_impl*/
 
+    template <typename T1>
+    T1 concat(T1 && x1) {
+        return x1;
+    } /*concat*/
+
     template <typename T1, typename T2>
     concat_impl<T1,T2> concat(T1 && x1, T2 && x2) {
         return concat_impl<T1,T2>(std::move(x1), std::move(x2));
diff --git a/utest/CMakeLists.txt b/utest/CMakeLists.txt
index 6e6352b5..1513f8bc 100644
--- a/utest/CMakeLists.txt
+++ b/utest/CMakeLists.txt
@@ -3,7 +3,7 @@
 set(SELF_EXECUTABLE_NAME utest.indentlog)
 set(SELF_SOURCE_FILES
     fixed.test.cpp quoted.test.cpp vector.test.cpp array.test.cpp timeutil.test.cpp tag.test.cpp
-    filename.test.cpp
+    filename.test.cpp code_location.test.cpp
     indentlog_utest_main.cpp)
 
 add_executable(${SELF_EXECUTABLE_NAME} ${SELF_SOURCE_FILES})
diff --git a/utest/code_location.test.cpp b/utest/code_location.test.cpp
new file mode 100644
index 00000000..64f1a0c4
--- /dev/null
+++ b/utest/code_location.test.cpp
@@ -0,0 +1,47 @@
+/* @file code_location.test.cpp */
+
+#include "indentlog/print/code_location.hpp"
+#include "indentlog/print/color.hpp"
+#include "indentlog/print/tag.hpp"
+#include <vector>
+#include <catch2/catch.hpp>
+
+using namespace xo;
+
+namespace ut {
+    struct code_location_tcase {
+        code_location_tcase() = default;
+        code_location_tcase(std::string_view file, std::uint32_t line, color_spec_type color, std::string_view output)
+            : file_{file}, line_{line}, color_{color}, output_{output} {}
+
+        /* target time value to test */
+        std::string_view file_;
+        std::uint32_t line_;
+        color_spec_type color_;
+        std::string_view output_;
+    }; /*code_location_tcase*/
+
+    std::vector<code_location_tcase> s_code_location_tcase_v(
+        {
+            code_location_tcase("/foo/bar", 123, color_spec_type::none(), "[bar:123]"),
+            code_location_tcase("/foo/bar", 123, color_spec_type::blue(), "[\033[31;34mbar\033[0m:123]"),
+            code_location_tcase("/foo/bar", 123, color_spec_type::xterm(196), "[\033[38;5;196mbar\033[0m:123]"),
+            code_location_tcase("/foo/bar", 123, color_spec_type::rgb(255, 127, 63), "[\033[38;2;255;127;63mbar\033[0m:123]"),
+        });
+
+    TEST_CASE("code_location", "[code_location]") {
+        for (std::uint32_t i_tc = 0, z_tc = s_code_location_tcase_v.size(); i_tc < z_tc; ++i_tc) {
+            code_location_tcase const & tc = s_code_location_tcase_v[i_tc];
+
+            INFO(tostr(xtag("i_tc", i_tc), xtag("file", tc.file_), xtag("line", tc.line_), xtag("color", tc.color_)));
+            INFO(xtag("tc.output", tc.output_));
+
+            std::stringstream ss;
+            ss << code_location(tc.file_, tc.line_, tc.color_);
+
+            REQUIRE(ss.str() == tc.output_);
+        }
+    } /*TEST_CASE(code_location)*/
+} /*namespace ut*/
+
+/* end code_location.test.cpp */
diff --git a/utest/filename.test.cpp b/utest/filename.test.cpp
index ee5fdfaf..ebff42b4 100644
--- a/utest/filename.test.cpp
+++ b/utest/filename.test.cpp
@@ -21,6 +21,8 @@ namespace ut {
     std::vector<filename_tcase> s_filename_tcase_v(
         {
             filename_tcase("foo", "foo"),
+            filename_tcase("/foo", "foo"),
+            filename_tcase("/foo/bar", "bar"),
         });
 
     TEST_CASE("filename", "[filename]") {