feat: add hex

tests/test_hex.cpp

@@ -0,0 +1,81 @@
+#include "catch.hpp"
+
+#include <cpputils/hex.h>
+#include <string>
+
+using namespace cpputils::hex;
+
+TEST_CASE("Hex conversion round-trip works", "[hex]") {
+  std::string original = "Hello, World!";
+  std::string hex = toHex(original);
+  std::string result = fromHex(hex);
+
+  REQUIRE(result == original);
+}
+
+TEST_CASE("Empty string conversion", "[hex]") {
+  std::string empty = "";
+  std::string hex = toHex(empty);
+  std::string result = fromHex(hex);
+
+  REQUIRE(hex.empty());
+  REQUIRE(result.empty());
+}
+
+TEST_CASE("Single character conversion", "[hex]") {
+  std::string single = "A";
+  std::string hex = toHex(single);
+  std::string result = fromHex(hex);
+
+  REQUIRE(result == single);
+}
+
+TEST_CASE("Non-printable ASCII characters", "[hex]") {
+  std::string nonPrintable;
+  for (char c = 0; c < 32; ++c) {
+    nonPrintable += c;
+  }
+
+  std::string hex = toHex(nonPrintable);
+  std::string result = fromHex(hex);
+
+  REQUIRE(result == nonPrintable);
+}
+
+TEST_CASE("Extended ASCII characters", "[hex]") {
+  std::string extended;
+  for (unsigned char c = 128; c < 255; ++c) {
+    extended += static_cast<char>(c);
+  }
+
+  std::string hex = toHex(extended);
+  std::string result = fromHex(hex);
+
+  REQUIRE(result == extended);
+}
+
+TEST_CASE("Hex string with lowercase and uppercase letters", "[hex]") {
+  std::string original = "abcABC123";
+  std::string hex = toHex(original);
+  std::string result = fromHex(hex);
+
+  REQUIRE(result == original);
+}
+
+TEST_CASE("Odd-length hex string should fail", "[hex]") {
+  std::string invalidHex = "A";
+  REQUIRE(fromHex(invalidHex).empty());
+}
+
+TEST_CASE("Hex string with invalid characters should fail", "[hex]") {
+  std::string invalidHex = "ZZ";
+  REQUIRE(fromHex(invalidHex).empty());
+}
+
+TEST_CASE("Large string conversion", "[hex]") {
+  std::string large(10000, 'x');
+  std::string hex = toHex(large);
+  std::string result = fromHex(hex);
+
+  REQUIRE(result == large);
+}