feat(error): add Error creation support with custom message

error/include/error/error.hpp

@@ -5,9 +5,19 @@
 namespace error {
 
 /**
- * @brief A struct that represents error information.
+ * @brief A class that represents error information.
  */
-struct Error : public std::exception {
+class Error : public std::exception {
+ private:
+  const char* message; /**< The error message. */
+
+ public:
+  /**
+   * @brief Constructs a new error with the given message.
+   * @param message An error message.
+   */
+  Error(const char* message);
+
   /**
    * @brief Returns the explanatory string.
    * @return Pointer to a null-terminated string with explanatory information.

error/src/error.cpp

@@ -2,6 +2,8 @@
 
 namespace error {
 
-const char* Error::what() const noexcept { return "unknown error"; }
+Error::Error(const char* message) : message(message) {}
+
+const char* Error::what() const noexcept { return message; }
 
 }  // namespace error

error/test/error_test.cpp

@@ -1,8 +1,9 @@
 #include <catch2/catch_test_macros.hpp>
 #include <error/error.hpp>
+#include <string>
 
-TEST_CASE("test Error::what") {
-  const error::Error err;
+TEST_CASE("Constructs an error") {
+  const error::Error err("unknown error");
   const std::string expected("unknown error");
   REQUIRE(expected.compare(err.what()) == 0);
 }