diff --git a/Makefile b/Makefile
index 91c9a03..2a3fa0d 100644
--- a/Makefile
+++ b/Makefile
@@ -15,6 +15,7 @@ OBJS =\
 TOOLS =\
 
 TESTS =\
+	test-hex\
 
 ifeq (${origin CC}, default)
 CC = g++
diff --git a/src/hex.cpp b/src/hex.cpp
index 39dee34..525dac2 100644
--- a/src/hex.cpp
+++ b/src/hex.cpp
@@ -23,7 +23,7 @@ static const int8_t hexmap[] = {
     -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 };
 
-namespace btc::data
+namespace hex
 {
     bool isValid(const std::string &str) noexcept
     {
diff --git a/test/test-hex.cpp b/test/test-hex.cpp
new file mode 100644
index 0000000..85c21e0
--- /dev/null
+++ b/test/test-hex.cpp
@@ -0,0 +1,31 @@
+#include <base/hex.hpp>
+#include <gtest/gtest.h>
+
+using namespace hex;
+
+TEST(hex, encode)
+{
+    std::vector<uint8_t> data = { 0x74, 0x65, 0x73, 0x74 };
+    EXPECT_EQ("74657374", encode(data));
+}
+TEST(hex, encode_1e6)
+{
+    std::vector<uint8_t> data(1e6);
+    encode(data);
+}
+TEST(hex, decode)
+{
+    std::vector<uint8_t> data = { 0x61, 0x6e, 0x6f };
+    EXPECT_EQ(decode("616e6f"), data);
+}
+TEST(hex, decode_1e6)
+{
+    std::string str(1e6, '0');
+    decode(str);
+}
+
+int main(int argc, char **argv)
+{
+    testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}
\ No newline at end of file