diff --git a/src/yycc/carton/binstore/storage.hpp b/src/yycc/carton/binstore/storage.hpp
index abf71bd..9c81efc 100644
--- a/src/yycc/carton/binstore/storage.hpp
+++ b/src/yycc/carton/binstore/storage.hpp
@@ -90,7 +90,7 @@ namespace yycc::carton::binstore::storage {
     public:
         template<NS_YYCC_BINSTORE_SERDES::SerDes T>
         NS_YYCC_BINSTORE_TYPES::BinstoreResult<std::pair<GetValueState, NS_YYCC_BINSTORE_SERDES::SerDesValueType<T>>> get_value(
-            NS_YYCC_BINSTORE_TYPES::Token token, const T& serdes = T()) {
+            NS_YYCC_BINSTORE_TYPES::Token token, const T& serdes = T{}) {
             // If we have value, we fetch it first
             if (this->has_value(token)) {
                 // Get raw value.
@@ -129,7 +129,7 @@ namespace yycc::carton::binstore::storage {
         template<NS_YYCC_BINSTORE_SERDES::SerDes T>
         NS_YYCC_BINSTORE_TYPES::BinstoreResult<SetValueState> set_value(NS_YYCC_BINSTORE_TYPES::Token token,
                                                                         const NS_YYCC_BINSTORE_SERDES::SerDesValueType<T>& value,
-                                                                        const T& serdes = T()) {
+                                                                        const T& serdes = T{}) {
             // First we try assign it.
             {
                 // Convert it into raw format.
diff --git a/src/yycc/carton/clap/manual.cpp b/src/yycc/carton/clap/manual.cpp
index dda3b85..37acc56 100644
--- a/src/yycc/carton/clap/manual.cpp
+++ b/src/yycc/carton/clap/manual.cpp
@@ -20,7 +20,7 @@ namespace yycc::carton::clap::manual {
 #pragma region Manual Translation
 
     ManualTr::ManualTr() :
-        author_and_version(u8"Invented by {0}. Version {1}."), usage_title(u8"Usage:"), usage_body(u8"{0} <options> ..."),
+        author_and_version(u8"Built by {0} with version {1}."), usage_title(u8"Usage:"), usage_body(u8"{0} <options> ..."),
         avail_opt(u8"Available options:"), avail_var(u8"Available environment variables:") {}
 
     ManualTr::~ManualTr() {}
@@ -100,14 +100,13 @@ namespace yycc::carton::clap::manual {
         const auto &summary = this->app.get_summary();
 
         TERMCOLOR::cprintln(summary.get_name(), TERMCOLOR::Color::Yellow, TERMCOLOR::Color::Default, TERMCOLOR::Attribute::Default, dst);
-        dst << summary.get_name() << std::endl;
         dst << FORMAT::format(trctx.author_and_version, summary.get_author(), summary.get_version()) << std::endl;
         dst << summary.get_description() << std::endl;
         dst << std::endl;
     }
 
     void Manual::print_help(std::ostream &dst) const {
-        this->print_version();
+        this->print_version(dst);
 
         // only print usage if we can fetch the name of executable
         auto executable = ENV::current_exe();
diff --git a/src/yycc/carton/clap/parser.cpp b/src/yycc/carton/clap/parser.cpp
index 58be3b1..8202c79 100644
--- a/src/yycc/carton/clap/parser.cpp
+++ b/src/yycc/carton/clap/parser.cpp
@@ -185,7 +185,7 @@ namespace yycc::carton::clap::parser {
         else return std::unexpected(rv.error());
     }
 
-    Parser::Parser(decltype(Parser::values)&& value) : values(std::move(values)) {}
+    Parser::Parser(decltype(Parser::values)&& values) : values(std::move(values)) {}
 
     Parser::~Parser() {}
 
@@ -200,7 +200,7 @@ namespace yycc::carton::clap::parser {
             return false;
         } else {
             // Found.
-            auto val = finder->second;
+            const auto& val = finder->second;
             if (val.has_value()) throw std::logic_error("get flag option as value option.");
             else return true;
         }
@@ -213,7 +213,7 @@ namespace yycc::carton::clap::parser {
             return std::unexpected(TYPES::ClapError::NotCaptured);
         } else {
             // Found.
-            auto val = finder->second;
+            const auto& val = finder->second;
             if (val.has_value()) return std::u8string_view(val.value());
             else throw std::logic_error("get value option as flag option.");
         }
diff --git a/src/yycc/carton/clap/parser.hpp b/src/yycc/carton/clap/parser.hpp
index f3480b4..67c72f6 100644
--- a/src/yycc/carton/clap/parser.hpp
+++ b/src/yycc/carton/clap/parser.hpp
@@ -32,7 +32,7 @@ namespace yycc::carton::clap::parser {
         static NS_YYCC_CLAP_TYPES::ClapResult<Parser> from_system(const NS_YYCC_CLAP_APPLICATION::Application& app);
 
     private:
-        Parser(decltype(Parser::values)&& value);
+        Parser(decltype(Parser::values)&& values);
 
     public:
         ~Parser();
@@ -46,7 +46,7 @@ namespace yycc::carton::clap::parser {
         NS_YYCC_CLAP_TYPES::ClapResult<bool> get_flag_option(NS_YYCC_CLAP_TYPES::Token token) const;
         template<NS_YYCC_CLAP_VALIDATOR::Validator T>
         NS_YYCC_CLAP_TYPES::ClapResult<NS_YYCC_CLAP_VALIDATOR::ValidatorReturnType<T>> get_value_option(NS_YYCC_CLAP_TYPES::Token token,
-                                                                                                        const T& validator = T()) const {
+                                                                                                        const T& validator = T{}) const {
             auto raw_value = this->get_raw_value_option(token);
             if (raw_value.has_value()) {
                 auto value = validator.validate(raw_value.value());
diff --git a/src/yycc/carton/clap/resolver.cpp b/src/yycc/carton/clap/resolver.cpp
index 777d6f9..38e9dc9 100644
--- a/src/yycc/carton/clap/resolver.cpp
+++ b/src/yycc/carton/clap/resolver.cpp
@@ -77,7 +77,7 @@ namespace yycc::carton::clap::resolver {
             return false;
         } else {
             // Found.
-            auto val = finder->second;
+            const auto& val = finder->second;
             if (val.has_value()) throw std::logic_error("get flag variable as value variable.");
             else return true;
         }
@@ -90,7 +90,7 @@ namespace yycc::carton::clap::resolver {
             return std::unexpected(TYPES::ClapError::NotCaptured);
         } else {
             // Found.
-            auto val = finder->second;
+            const auto& val = finder->second;
             if (val.has_value()) return std::u8string_view(val.value());
             else throw std::logic_error("get value variable as flag variable.");
         }
diff --git a/src/yycc/carton/clap/validator.hpp b/src/yycc/carton/clap/validator.hpp
index 19f72fa..da68685 100644
--- a/src/yycc/carton/clap/validator.hpp
+++ b/src/yycc/carton/clap/validator.hpp
@@ -42,6 +42,7 @@ namespace yycc::carton::clap::validator {
 
     template<std::integral T, auto TMin = std::numeric_limits<T>::min(), auto TMax = std::numeric_limits<T>::max()>
     struct IntegralValidator {
+        IntegralValidator() = default;
         YYCC_DEFAULT_COPY_MOVE(IntegralValidator)
 
         static_assert(TMin <= TMax);
@@ -59,9 +60,14 @@ namespace yycc::carton::clap::validator {
 
     template<std::floating_point T, auto TMin = std::numeric_limits<T>::lowest(), auto TMax = std::numeric_limits<T>::max()>
     struct FloatingPointValidator {
+        FloatingPointValidator() {
+            // TODO: Remove this and make it "= default" when 3 common STL make std::isfinite become constexpr.
+            if (!std::isfinite(TMin)) throw std::logic_error("invalid float minimum value.");
+            if (!std::isfinite(TMax)) throw std::logic_error("invalid float maximum value.");
+        }
         YYCC_DEFAULT_COPY_MOVE(FloatingPointValidator)
 
-        // TODO: Use static_assert once 3 common STL make this become constexpr.
+        // TODO: Use static_assert once 3 common STL make std::isfinite become constexpr.
         //static_assert(std::isfinite<T>(TMin));
         //static_assert(std::isfinite<T>(TMax));
         static_assert(TMin <= TMax);
@@ -78,6 +84,7 @@ namespace yycc::carton::clap::validator {
     };
 
     struct BoolValidator {
+        BoolValidator() = default;
         YYCC_DEFAULT_COPY_MOVE(BoolValidator)
 
         using ReturnType = bool;
@@ -89,6 +96,7 @@ namespace yycc::carton::clap::validator {
     };
 
     struct StringValidator {
+        StringValidator() = default;
         YYCC_DEFAULT_COPY_MOVE(StringValidator)
 
         using ReturnType = std::u8string;
diff --git a/src/yycc/carton/termcolor.cpp b/src/yycc/carton/termcolor.cpp
index d39430b..0d54b8c 100644
--- a/src/yycc/carton/termcolor.cpp
+++ b/src/yycc/carton/termcolor.cpp
@@ -216,7 +216,7 @@ namespace yycc::carton::termcolor {
         dst << colored(words, foreground, background, styles);
     }
 
-    void ecprint(const std::u8string_view& words, Color foreground, Color background, Attribute styles) {
+    void ceprint(const std::u8string_view& words, Color foreground, Color background, Attribute styles) {
         cprint(words, foreground, background, styles, std::cerr);
     }
 
@@ -225,7 +225,7 @@ namespace yycc::carton::termcolor {
         dst << std::endl;
     }
 
-    void ecprintln(const std::u8string_view& words, Color foreground, Color background, Attribute styles) {
+    void ceprintln(const std::u8string_view& words, Color foreground, Color background, Attribute styles) {
         cprintln(words, foreground, background, styles, std::cerr);
     }
 
diff --git a/test/yycc/carton/clap.cpp b/test/yycc/carton/clap.cpp
index 578c6b2..9f060e3 100644
--- a/test/yycc/carton/clap.cpp
+++ b/test/yycc/carton/clap.cpp
@@ -10,18 +10,21 @@ namespace yycctest::carton::clap {
     using Token = CLAP::types::Token;
     namespace validator = CLAP::validator;
 
-    TEST(CartonClap, BadOption) {
+    // YYC MARK:
+    // GoogleTest do not allow use TEST and TEST_F in the same test suite
+    // So I was forcely split following builder checker into independent test suit.
+
+    TEST(CartonClapOption, BadOption) {
         // No short name and long name.
         EXPECT_ANY_THROW(auto opt = CLAP::option::Option(std::nullopt, std::nullopt, std::nullopt, u8""));
         // Empty short name or long name.
         EXPECT_ANY_THROW(auto opt = CLAP::option::Option(u8"", std::nullopt, std::nullopt, u8""));
         EXPECT_ANY_THROW(auto opt = CLAP::option::Option(std::nullopt, u8"", std::nullopt, u8""));
         // Bad short name
-        EXPECT_ANY_THROW(auto opt = CLAP::option::Option(u8"fuck", std::nullopt, std::nullopt, u8""));
         EXPECT_ANY_THROW(auto opt = CLAP::option::Option(u8"-", std::nullopt, std::nullopt, u8""));
     }
 
-    TEST(CartonClap, BadOptions) {
+    TEST(CartonClapOption, BadOptions) {
         // Duplicated.
         {
             auto options = CLAP::option::OptionCollection();
@@ -36,12 +39,12 @@ namespace yycctest::carton::clap {
         }
     }
 
-    TEST(CartonClap, BadVariable) {
+    TEST(CartonClapVariable, BadVariable) {
         // Empty name
         EXPECT_ANY_THROW(auto var = CLAP::variable::Variable(u8"", u8"", true));
     }
 
-    TEST(CartonClap, BadVariables) {
+    TEST(CartonClapVariable, BadVariables) {
         // Duplicated.
         {
             auto variables = CLAP::variable::VariableCollection();