diff --git a/src/core/CMakeLists.txt b/src/core/CMakeLists.txt
index a8c32b3..8f39fae 100644
--- a/src/core/CMakeLists.txt
+++ b/src/core/CMakeLists.txt
@@ -1,6 +1,6 @@
 cmake_minimum_required(VERSION 3.0)
 
-set(CMAKE_CXX_STANDARD 20)
+set(CMAKE_CXX_STANDARD 23)
 
 project(klotski-core VERSION 0.9.1 LANGUAGES CXX)
 
diff --git a/src/core/all_cases/all_cases.cc b/src/core/all_cases/all_cases.cc
index 27a4884..3a1af1b 100644
--- a/src/core/all_cases/all_cases.cc
+++ b/src/core/all_cases/all_cases.cc
@@ -88,8 +88,6 @@ void AllCases::build_parallel(Executor &&executor) noexcept {
     }
     std::vector<std::future<void>> futures;
     for (auto head : case_heads()) {
-        // TODO: using std::move_only_function in C++23
-        //       -> avoid using std::shared_ptr<std::promise<void>>
         auto promise = std::make_shared<std::promise<void>>();
         futures.emplace_back(promise->get_future());
         executor([head, promise = std::move(promise)]() {
diff --git a/src/core/all_cases/all_cases.h b/src/core/all_cases/all_cases.h
index 09c8fe5..21f0412 100644
--- a/src/core/all_cases/all_cases.h
+++ b/src/core/all_cases/all_cases.h
@@ -89,25 +89,6 @@ private:
     static void spawn_ranges(Ranges &ranges, int, int, int, int) noexcept;
 };
 
-inline BasicRanges& BasicRanges::instance() noexcept {
-    static BasicRanges instance;
-    return instance;
-}
-
-inline Ranges& BasicRanges::get_ranges() noexcept {
-    static Ranges ranges;
-    return ranges;
-}
-
-inline const Ranges& BasicRanges::fetch() noexcept {
-    this->build();
-    return get_ranges();
-}
-
-inline bool BasicRanges::is_available() const noexcept {
-    return available_; // no mutex required in one-way state
-}
-
 // ----------------------------------------------------------------------------------------- //
 
 class AllCases {
@@ -131,26 +112,9 @@ private:
     static void build_cases(int head, Ranges &release) noexcept;
 };
 
-inline AllCases& AllCases::instance() noexcept {
-    static AllCases instance;
-    return instance;
-}
-
-inline RangesUnion& AllCases::get_cases() noexcept {
-    static RangesUnion cases;
-    return cases;
-}
-
-inline const RangesUnion& AllCases::fetch() noexcept {
-    this->build();
-    return get_cases();
-}
-
-inline bool AllCases::is_available() const noexcept {
-    return available_; // no mutex required in one-way state
-}
-
 // ----------------------------------------------------------------------------------------- //
 
 } // namespace cases
 } // namespace klotski
+
+#include "inline_impl.h"
diff --git a/src/core/all_cases/inline_impl.h b/src/core/all_cases/inline_impl.h
new file mode 100644
index 0000000..fe44af0
--- /dev/null
+++ b/src/core/all_cases/inline_impl.h
@@ -0,0 +1,51 @@
+#pragma once
+
+namespace klotski {
+namespace cases {
+
+// ----------------------------------------------------------------------------------------- //
+
+inline BasicRanges& BasicRanges::instance() noexcept {
+    static BasicRanges instance;
+    return instance;
+}
+
+inline Ranges& BasicRanges::get_ranges() noexcept {
+    static Ranges ranges;
+    return ranges;
+}
+
+inline const Ranges& BasicRanges::fetch() noexcept {
+    this->build();
+    return get_ranges();
+}
+
+inline bool BasicRanges::is_available() const noexcept {
+    return available_; // no mutex required in one-way state
+}
+
+// ----------------------------------------------------------------------------------------- //
+
+inline AllCases& AllCases::instance() noexcept {
+    static AllCases instance;
+    return instance;
+}
+
+inline RangesUnion& AllCases::get_cases() noexcept {
+    static RangesUnion cases;
+    return cases;
+}
+
+inline const RangesUnion& AllCases::fetch() noexcept {
+    this->build();
+    return get_cases();
+}
+
+inline bool AllCases::is_available() const noexcept {
+    return available_; // no mutex required in one-way state
+}
+
+// ----------------------------------------------------------------------------------------- //
+
+} // namespace codec
+} // namespace klotski
diff --git a/src/core/common_code/sundry.cc b/src/core/common_code/sundry.cc
index d0eb320..660b258 100644
--- a/src/core/common_code/sundry.cc
+++ b/src/core/common_code/sundry.cc
@@ -39,11 +39,9 @@ std::optional<CommonCode> CommonCode::from_string(std::string &&common_code) noe
 }
 
 std::optional<CommonCode> CommonCode::from_string(const std::string &common_code) noexcept {
-    auto code = string_decode(common_code);
-    if (!code.has_value()) {
-        return std::nullopt; // invalid string
-    }
-    return CommonCode::unsafe_create(code.value());
+    return string_decode(common_code).transform([](auto code) {
+        return CommonCode::unsafe_create(code);
+    });
 }
 
 // ----------------------------------------------------------------------------------------- //
@@ -52,13 +50,10 @@ CommonCode CommonCode::from_raw_code(RawCode raw_code) noexcept {
     return raw_code.to_common_code();
 }
 
-// TODO: using `std::optional::transform` in C++23
 std::optional<CommonCode> CommonCode::from_raw_code(uint64_t raw_code) noexcept {
-    auto code = RawCode::create(raw_code);
-    if (!code.has_value()) {
-        return std::nullopt; // invalid raw code
-    }
-    return code->to_common_code();
+    return RawCode::create(raw_code).transform([](auto raw_code) {
+        return raw_code.to_common_code();
+    });
 }
 
 // ----------------------------------------------------------------------------------------- //
@@ -68,27 +63,21 @@ CommonCode CommonCode::from_short_code(ShortCode short_code) noexcept {
 }
 
 std::optional<CommonCode> CommonCode::from_short_code(uint32_t short_code) noexcept {
-    auto code = ShortCode::create(short_code);
-    if (!code.has_value()) {
-        return std::nullopt; // invalid short code
-    }
-    return code->to_common_code();
+    return ShortCode::create(short_code).transform([](auto short_code) {
+        return short_code.to_common_code();
+    });
 }
 
 std::optional<CommonCode> CommonCode::from_short_code(std::string &&short_code) noexcept {
-    auto code = ShortCode::from_string(std::move(short_code));
-    if (!code.has_value()) {
-        return std::nullopt; // invalid short code
-    }
-    return code->to_common_code();
+    return ShortCode::from_string(std::move(short_code)).transform([](auto short_code) {
+        return short_code.to_common_code();
+    });
 }
 
 std::optional<CommonCode> CommonCode::from_short_code(const std::string &short_code) noexcept {
-    auto code = ShortCode::from_string(short_code);
-    if (!code.has_value()) {
-        return std::nullopt; // invalid short code
-    }
-    return code->to_common_code();
+    return ShortCode::from_string(short_code).transform([](auto short_code) {
+        return short_code.to_common_code();
+    });
 }
 
 // ----------------------------------------------------------------------------------------- //
diff --git a/src/core/main.cc b/src/core/main.cc
index 4c59625..5694eed 100644
--- a/src/core/main.cc
+++ b/src/core/main.cc
@@ -1,4 +1,7 @@
+#include <thread>
 #include <iostream>
+#include <algorithm>
+
 #include "raw_code.h"
 #include "all_cases.h"
 #include "short_code.h"
@@ -11,10 +14,12 @@ using klotski::codec::RawCode;
 using klotski::codec::ShortCode;
 using klotski::codec::CommonCode;
 
+using klotski::codec::SHORT_CODE_LIMIT;
+
 int main() {
 
-//    AllCases::instance().build();
-    BasicRanges::instance().build();
+    AllCases::instance().build();
+//    BasicRanges::instance().build();
 
 //    std::vector<uint64_t> common_codes;
 //    common_codes.reserve(klotski::cases::ALL_CASES_NUM_);
@@ -31,8 +36,14 @@ int main() {
 //        common_codes_str.emplace_back(CommonCode::string_encode(x, false));
 //    }
 
+    ShortCode::speed_up(true);
+
     auto start = clock();
 
+    for (uint32_t short_code = 0; short_code < SHORT_CODE_LIMIT; ++short_code) {
+        ShortCode::unsafe_create(short_code).to_common_code(true);
+    }
+
 //    for (auto common_code : common_codes) {
 //        printf("%llX\n", common_code);
 //        CommonCode::string_encode(common_code, true);
diff --git a/src/core/raw_code/convert.cc b/src/core/raw_code/convert.cc
index d5bdb23..e5c05e3 100644
--- a/src/core/raw_code/convert.cc
+++ b/src/core/raw_code/convert.cc
@@ -5,8 +5,8 @@
 namespace klotski {
 namespace codec {
 
-/// NOTE: ensure that input raw code is valid!
-uint64_t RawCode::compact(uint64_t raw_code) noexcept { // raw code --> common code
+/// Convert RawCode to CommonCode.
+uint64_t RawCode::compact(uint64_t raw_code) noexcept {
     int unfilled = 16;
     uint64_t head = 0; // 2x2 block address
     uint32_t range = 0;
@@ -34,8 +34,8 @@ uint64_t RawCode::compact(uint64_t raw_code) noexcept { // raw code --> common c
     return head | (range << (unfilled << 1)); // fill low bits as zero
 }
 
-/// NOTE: ensure that input common code is valid!
-uint64_t RawCode::extract(uint64_t common_code) noexcept { // common code --> raw code
+/// Convert CommonCode to RawCode.
+uint64_t RawCode::extract(uint64_t common_code) noexcept {
     auto code = K_MASK_2x2 << (common_code >> 32) * 3; // flag for 2x2 block
     auto range = range_reverse((uint32_t)common_code); // reversed range
 
diff --git a/src/core/raw_code/mirror.cc b/src/core/raw_code/mirror.cc
index aecd7c5..06a7aaf 100644
--- a/src/core/raw_code/mirror.cc
+++ b/src/core/raw_code/mirror.cc
@@ -116,5 +116,7 @@ bool RawCode::check_horizontal_mirror(uint64_t raw_code) noexcept {
         && !(MASK_MIRROR_H2 & ((raw_code >> 3) ^ raw_code));
 }
 
+// ----------------------------------------------------------------------------------------- //
+
 } // namespace codec
 } // namespace klotski
diff --git a/src/core/raw_code/sundry.cc b/src/core/raw_code/sundry.cc
index 777eb97..224cedf 100644
--- a/src/core/raw_code/sundry.cc
+++ b/src/core/raw_code/sundry.cc
@@ -23,27 +23,21 @@ RawCode RawCode::from_common_code(CommonCode common_code) noexcept {
 }
 
 std::optional<RawCode> RawCode::from_common_code(uint64_t common_code) noexcept {
-    auto code = CommonCode::create(common_code);
-    if (!code.has_value()) {
-        return std::nullopt; // invalid common code
-    }
-    return code->to_raw_code();
+    return CommonCode::create(common_code).transform([](auto common_code) {
+        return common_code.to_raw_code();
+    });
 }
 
 std::optional<RawCode> RawCode::from_common_code(std::string &&common_code) noexcept {
-    auto code = CommonCode::from_string(std::move(common_code));
-    if (!code.has_value()) {
-        return std::nullopt; // invalid common code
-    }
-    return code->to_raw_code();
+    return CommonCode::from_short_code(std::move(common_code)).transform([](auto common_code) {
+        return common_code.to_raw_code();
+    });
 }
 
 std::optional<RawCode> RawCode::from_common_code(const std::string &common_code) noexcept {
-    auto code = CommonCode::from_string(common_code);
-    if (!code.has_value()) {
-        return std::nullopt; // invalid common code
-    }
-    return code->to_raw_code();
+    return CommonCode::from_string(common_code).transform([](auto common_code) {
+        return common_code.to_raw_code();
+    });
 }
 
 // ----------------------------------------------------------------------------------------- //
diff --git a/src/core/short_code/short_code.cc b/src/core/short_code/short_code.cc
index 9037bf3..b2a8d7b 100644
--- a/src/core/short_code/short_code.cc
+++ b/src/core/short_code/short_code.cc
@@ -18,21 +18,7 @@ void ShortCode::speed_up(bool fast_mode) noexcept {
     } else {
         BasicRanges::instance().build();
     }
-    // FIXME: setting up `fast_available_`
 }
 
-//void ShortCode::speed_up(ShortCode::Mode mode) {
-//    if (fast_mode_available_) {
-//        return; // fast mode already available
-//    }
-//    if (mode == ShortCode::FAST) { // build fast mode data
-//        AllCases::build(); // blocking function
-//        fast_mode_available_ = true;
-//    } else if (!normal_mode_available_) { // build normal mode data
-//        BasicRanges::build(); // blocking function
-//        normal_mode_available_ = true;
-//    }
-//}
-
 } // namespace codec
 } // namespace klotski
diff --git a/src/core/short_code/short_code.h b/src/core/short_code/short_code.h
index a4353a1..85d4fef 100644
--- a/src/core/short_code/short_code.h
+++ b/src/core/short_code/short_code.h
@@ -106,7 +106,6 @@ public:
 
 private:
     uint32_t code_;
-    static bool fast_available_; // TODO: try to remove it
 
     static uint64_t fast_decode(uint32_t short_code) noexcept;
     static uint32_t fast_encode(uint64_t common_code) noexcept;
diff --git a/src/core/short_code/sundry.cc b/src/core/short_code/sundry.cc
index e50daee..ccf7c5d 100644
--- a/src/core/short_code/sundry.cc
+++ b/src/core/short_code/sundry.cc
@@ -1,17 +1,19 @@
 #include "short_code.h"
 #include "common_code.h"
 
+using klotski::cases::AllCases;
+
 namespace klotski {
 namespace codec {
 
 // ----------------------------------------------------------------------------------------- //
 
 ShortCode::ShortCode(CommonCode common_code) noexcept {
-//    if (fast_available_) {
+    if (AllCases::instance().is_available()) {
         code_ = fast_encode(common_code.unwrap());
-//    } else {
-//        code_ = tiny_encode(common_code.unwrap());
-//    }
+    } else {
+        code_ = tiny_encode(common_code.unwrap());
+    }
 }
 
 // ----------------------------------------------------------------------------------------- //
@@ -21,10 +23,10 @@ std::string ShortCode::to_string() const noexcept {
 }
 
 CommonCode ShortCode::to_common_code() const noexcept {
-//    if (fast_available_) {
+    if (AllCases::instance().is_available()) {
         return CommonCode::unsafe_create(fast_decode(code_));
-//    }
-//    return CommonCode::unsafe_create(tiny_decode(code_));
+    }
+    return CommonCode::unsafe_create(tiny_decode(code_));
 }
 
 // ----------------------------------------------------------------------------------------- //
@@ -34,11 +36,9 @@ std::optional<ShortCode> ShortCode::from_string(std::string &&short_code) noexce
 }
 
 std::optional<ShortCode> ShortCode::from_string(const std::string &short_code) noexcept {
-    auto code = ShortCode::string_decode(short_code);
-    if (!code.has_value()) {
-        return std::nullopt; // invalid string
-    }
-    return ShortCode::unsafe_create(code.value());
+    return ShortCode::string_decode(short_code).transform([](auto code) {
+        return ShortCode::unsafe_create(code);
+    });
 }
 
 // ----------------------------------------------------------------------------------------- //
@@ -48,27 +48,21 @@ ShortCode ShortCode::from_common_code(CommonCode common_code) noexcept {
 }
 
 std::optional<ShortCode> ShortCode::from_common_code(uint64_t common_code) noexcept {
-    auto code = CommonCode::create(common_code);
-    if (!code.has_value()) {
-        return std::nullopt; // invalid common code
-    }
-    return code->to_short_code();
+    return CommonCode::create(common_code).transform([](auto common_code) {
+        return common_code.to_short_code();
+    });
 }
 
 std::optional<ShortCode> ShortCode::from_common_code(std::string &&common_code) noexcept {
-    auto code = CommonCode::from_string(std::move(common_code));
-    if (!code.has_value()) {
-        return std::nullopt; // invalid common code
-    }
-    return code->to_short_code();
+    return CommonCode::from_string(std::move(common_code)).transform([](auto common_code) {
+        return common_code.to_short_code();
+    });
 }
 
 std::optional<ShortCode> ShortCode::from_common_code(const std::string &common_code) noexcept {
-    auto code = CommonCode::from_string(common_code);
-    if (!code.has_value()) {
-        return std::nullopt; // invalid common code
-    }
-    return code->to_short_code();
+    return CommonCode::from_string(common_code).transform([](auto common_code) {
+        return common_code.to_short_code();
+    });
 }
 
 // ----------------------------------------------------------------------------------------- //
diff --git a/src/core_test/codec/common_code.cc b/src/core_test/codec/common_code.cc
index 69e37e5..6b1a908 100644
--- a/src/core_test/codec/common_code.cc
+++ b/src/core_test/codec/common_code.cc
@@ -1,5 +1,6 @@
 #include <algorithm>
 
+#include "sample.h"
 #include "all_cases.h"
 #include "raw_code.h"
 #include "short_code.h"
@@ -14,9 +15,6 @@ using klotski::codec::CommonCode;
 using klotski::cases::AllCases;
 using klotski::cases::ALL_CASES_NUM_;
 
-const static uint64_t TEST_CODE = 0x1'A9BF'0C00;
-const static std::string TEST_CODE_STR = "1A9BF0C00";
-
 TEST(CommonCode, validity) {
     EXPECT_NE(CommonCode::check(0x3'A9'BF'0C'00), true); // invalid 2x2 block
     EXPECT_NE(CommonCode::check(0x1'D9'BF'0C'00), true); // invalid block range
@@ -29,23 +27,76 @@ TEST(CommonCode, validity) {
 }
 
 TEST(CommonCode, operators) {
-    auto common_code = CommonCode::create(TEST_CODE).value();
+    auto common_code = CommonCode::create(TEST_C_CODE).value();
 
     std::ostringstream tmp;
     tmp << common_code; // ostream capture
-    EXPECT_EQ(tmp.str(), TEST_CODE_STR);
-    EXPECT_EQ((uint64_t)common_code, TEST_CODE); // convert as uint64_t
+    EXPECT_EQ(tmp.str(), TEST_C_CODE_STR);
+    EXPECT_EQ((uint64_t)common_code, TEST_C_CODE); // convert as uint64_t
 
-    EXPECT_EQ(TEST_CODE, common_code); // uint64_t == CommonCode
-    EXPECT_EQ(common_code, TEST_CODE); // CommonCode == uint64_t
+    EXPECT_EQ(TEST_C_CODE, common_code); // uint64_t == CommonCode
+    EXPECT_EQ(common_code, TEST_C_CODE); // CommonCode == uint64_t
     EXPECT_EQ(common_code, common_code); // CommonCode == CommonCode
 
-    EXPECT_NE(TEST_CODE + 1, common_code); // uint64_t != CommonCode
-    EXPECT_NE(common_code, TEST_CODE + 1); // CommonCode != uint64_t
-    EXPECT_NE(common_code, CommonCode::unsafe_create(TEST_CODE + 1)); // CommonCode != CommonCode
+    EXPECT_NE(TEST_C_CODE + 1, common_code); // uint64_t != CommonCode
+    EXPECT_NE(common_code, TEST_C_CODE + 1); // CommonCode != uint64_t
+    EXPECT_NE(common_code, CommonCode::unsafe_create(TEST_C_CODE + 1)); // CommonCode != CommonCode
+
+    EXPECT_LT(common_code, CommonCode::unsafe_create(TEST_C_CODE + 1)); // CommonCode < CommonCode
+    EXPECT_GT(CommonCode::unsafe_create(TEST_C_CODE + 1), common_code); // CommonCode > CommonCode
+}
 
-    EXPECT_LT(common_code, CommonCode::unsafe_create(TEST_CODE + 1)); // CommonCode < CommonCode
-    EXPECT_GT(CommonCode::unsafe_create(TEST_CODE + 1), common_code); // CommonCode > CommonCode
+TEST(CommonCode, initializate) {
+    auto raw_code = RawCode::unsafe_create(TEST_R_CODE);
+    auto short_code = ShortCode::unsafe_create(TEST_S_CODE);
+
+    // CommonCode(...)
+    EXPECT_EQ(CommonCode(raw_code), TEST_C_CODE);
+    EXPECT_EQ(CommonCode(short_code), TEST_C_CODE);
+
+    // CommonCode::create(uint64_t)
+    EXPECT_TRUE(CommonCode::create(TEST_C_CODE).has_value());
+    EXPECT_FALSE(CommonCode::create(TEST_C_CODE_ERR).has_value());
+    EXPECT_EQ(CommonCode::create(TEST_C_CODE), TEST_C_CODE);
+
+    // CommonCode::unsafe_create(uint64_t)
+    EXPECT_EQ(CommonCode::unsafe_create(TEST_C_CODE), TEST_C_CODE);
+
+    // CommonCode::from_string(const std::string &)
+    EXPECT_TRUE(CommonCode::from_string(TEST_C_CODE_STR).has_value());
+    EXPECT_FALSE(CommonCode::from_string(TEST_C_CODE_STR_ERR).has_value());
+    EXPECT_EQ(CommonCode::from_string(TEST_C_CODE_STR), TEST_C_CODE);
+
+    // CommonCode::from_string(std::string &&)
+    EXPECT_TRUE(CommonCode::from_string(TEST_C_CODE_STR_RV).has_value());
+    EXPECT_FALSE(CommonCode::from_string(TEST_C_CODE_STR_ERR_RV).has_value());
+    EXPECT_EQ(CommonCode::from_string(TEST_C_CODE_STR_RV), TEST_C_CODE);
+
+    // CommonCode::from_raw_code(RawCode)
+    EXPECT_EQ(CommonCode::from_raw_code(raw_code), TEST_C_CODE);
+
+    // CommonCode::from_raw_code(uint64_t)
+    EXPECT_TRUE(CommonCode::from_raw_code(TEST_R_CODE).has_value());
+    EXPECT_FALSE(CommonCode::from_raw_code(TEST_R_CODE_ERR).has_value());
+    EXPECT_EQ(CommonCode::from_raw_code(TEST_R_CODE), TEST_C_CODE);
+
+    // CommonCode::from_short_code(ShortCode)
+    EXPECT_EQ(CommonCode::from_short_code(short_code), TEST_C_CODE);
+
+    // CommonCode::from_short_code(uint32_t)
+    EXPECT_TRUE(CommonCode::from_short_code(TEST_S_CODE).has_value());
+    EXPECT_FALSE(CommonCode::from_short_code(TEST_S_CODE_ERR).has_value());
+    EXPECT_EQ(CommonCode::from_short_code(TEST_S_CODE), TEST_C_CODE);
+
+    // CommonCode::from_short_code(const std::string &)
+    EXPECT_TRUE(CommonCode::from_short_code(TEST_S_CODE_STR).has_value());
+    EXPECT_FALSE(CommonCode::from_short_code(TEST_S_CODE_STR_ERR).has_value());
+    EXPECT_EQ(CommonCode::from_short_code(TEST_S_CODE_STR), TEST_C_CODE);
+
+    // CommonCode::from_short_code(std::string &&)
+    EXPECT_TRUE(CommonCode::from_short_code(TEST_S_CODE_STR_RV).has_value());
+    EXPECT_FALSE(CommonCode::from_short_code(TEST_S_CODE_STR_ERR_RV).has_value());
+    EXPECT_EQ(CommonCode::from_short_code(TEST_S_CODE_STR_RV), TEST_C_CODE);
 }
 
 TEST(CommonCode, code_verify) {
@@ -54,7 +105,7 @@ TEST(CommonCode, code_verify) {
         pool.push_task([](uint64_t head) {
             for (auto range : AllCases::instance().fetch()[head]) {
                 auto code = head << 32 | range;
-                EXPECT_TRUE(CommonCode::check(code)); // verify all valid code
+                EXPECT_TRUE(CommonCode::check(code)); // verify all cases
             }
         }, head);
     }
@@ -97,11 +148,11 @@ TEST(CommonCode, code_string) {
 }
 
 TEST(CommonCode, code_convert) {
-    auto common_code = CommonCode::create(TEST_CODE).value();
-    EXPECT_EQ(common_code.unwrap(), TEST_CODE);
-    EXPECT_EQ(common_code.to_string(), TEST_CODE_STR);
-    EXPECT_EQ(common_code.to_raw_code(), RawCode(common_code));
-    EXPECT_EQ(common_code.to_short_code(), ShortCode(common_code));
+    auto common_code = CommonCode::unsafe_create(TEST_C_CODE);
+    EXPECT_EQ(common_code.unwrap(), TEST_C_CODE);
+    EXPECT_EQ(common_code.to_string(), TEST_C_CODE_STR);
+    EXPECT_EQ(common_code.to_raw_code(), TEST_R_CODE);
+    EXPECT_EQ(common_code.to_short_code(), TEST_S_CODE);
 
     auto code_shorten = common_code.to_string(true);
     EXPECT_EQ(CommonCode::from_string(code_shorten), common_code); // l-value
@@ -112,38 +163,6 @@ TEST(CommonCode, code_convert) {
     EXPECT_EQ(CommonCode::from_string(std::move(code_normal)), common_code); // r-value
 }
 
-TEST(CommonCode, initializate) {
-    EXPECT_TRUE(CommonCode::create(TEST_CODE).has_value());
-    EXPECT_EQ(CommonCode::create(TEST_CODE), TEST_CODE);
-    EXPECT_EQ(CommonCode::unsafe_create(TEST_CODE), TEST_CODE);
-
-    auto common_code = CommonCode::create(TEST_CODE).value();
-    EXPECT_EQ(CommonCode(RawCode(common_code)), TEST_CODE);
-    EXPECT_EQ(CommonCode(ShortCode(common_code)), TEST_CODE);
-
-    EXPECT_TRUE(CommonCode::from_string(TEST_CODE_STR).has_value());
-    EXPECT_EQ(CommonCode::from_string(TEST_CODE_STR), TEST_CODE); // l-value
-    EXPECT_EQ(CommonCode::from_string(std::string(TEST_CODE_STR)), TEST_CODE); // r-value
-
-    auto raw_code = RawCode(common_code);
-    auto raw_code_val = raw_code.unwrap();
-    EXPECT_EQ(CommonCode::from_raw_code(raw_code), TEST_CODE);
-    EXPECT_TRUE(CommonCode::from_raw_code(raw_code_val).has_value());
-    EXPECT_EQ(CommonCode::from_raw_code(raw_code_val), TEST_CODE);
-
-    auto short_code = ShortCode(common_code);
-    auto short_code_val = short_code.unwrap();
-    auto short_code_str = short_code.to_string();
-    EXPECT_TRUE(CommonCode::from_short_code(short_code_val).has_value());
-    EXPECT_TRUE(CommonCode::from_short_code(short_code_str).has_value());
-    EXPECT_TRUE(CommonCode::from_short_code(std::string(short_code_str)).has_value());
-
-    EXPECT_EQ(CommonCode::from_short_code(short_code_val), TEST_CODE);
-    EXPECT_EQ(CommonCode::from_short_code(short_code), TEST_CODE);
-    EXPECT_EQ(CommonCode::from_short_code(short_code_str), TEST_CODE); // l-value
-    EXPECT_EQ(CommonCode::from_short_code(std::string(short_code_str)), TEST_CODE); // r-value
-}
-
 TEST(CommonCode, DISABLED_global) {
     std::vector<uint64_t> common_codes;
     common_codes.reserve(ALL_CASES_NUM_);
diff --git a/src/core_test/codec/sample.h b/src/core_test/codec/sample.h
new file mode 100644
index 0000000..0178501
--- /dev/null
+++ b/src/core_test/codec/sample.h
@@ -0,0 +1,36 @@
+#pragma once
+
+#include <string>
+#include <cstdint>
+
+// ----------------------------------------------------------------------------------------- //
+
+// Valid RawCode
+const uint64_t TEST_R_CODE = 0x0603'EDF5'CAFF'F5E2;
+
+// Valid ShortCode
+const uint32_t TEST_S_CODE = 4091296;
+const std::string TEST_S_CODE_STR = "4WVE1";
+#define TEST_S_CODE_STR_RV std::string(TEST_S_CODE_STR) // r-value
+
+// Valid CommonCode
+const uint64_t TEST_C_CODE = 0x1'A9BF'0C00;
+const std::string TEST_C_CODE_STR = "1A9BF0C00";
+#define TEST_C_CODE_STR_RV std::string(TEST_C_CODE_STR) // r-value
+
+// ----------------------------------------------------------------------------------------- //
+
+// Invalid RawCode
+const static uint64_t TEST_R_CODE_ERR = 0x1603'ED00'CAFF'F5E2;
+
+// Invalid ShortCode
+const static uint32_t TEST_S_CODE_ERR = 1234564323;
+const static std::string TEST_S_CODE_STR_ERR = "ZZZZZZ";
+#define TEST_S_CODE_STR_ERR_RV std::string(TEST_S_CODE_STR_ERR) // r-value
+
+// Invalid CommonCode
+const static uint64_t TEST_C_CODE_ERR = 0x3'A9BF'0C00;
+const static std::string TEST_C_CODE_STR_ERR = "0123456789";
+#define TEST_C_CODE_STR_ERR_RV std::string(TEST_C_CODE_STR_ERR) // r-value
+
+// ----------------------------------------------------------------------------------------- //