add issue_id class with generation algorithm

- the cass is needed to create issues
- the algorithm belongs at least close to the issue_id class
- the algorithm does _not_ belong to the application service

src/domain/CMakeLists.txt

@@ -2,6 +2,7 @@ set(DOMAIN_SOURCES
     application_service.cpp
     description.cpp
     domain_error.cpp
+    issue_id.cpp
     title.cpp
     )
 

src/domain/application_service.cpp

@@ -1,28 +1,22 @@
 #include "application_service.hpp"
 
-#include <range/v3/view.hpp>
-#include <range/v3/range/conversion.hpp>
 #include <string>
 
+#include "description.hpp"
+#include "issue_id.hpp"
+#include "title.hpp"
+
 using namespace fix::domain;
 using namespace std::literals;
-namespace rv = ranges::views;
 
 std::string application_service::create(std::string_view title, std::string_view description) { // NOLINT
-  (void) description;
-
-  // clang-format off
-  const auto id_prefix = title
-      | rv::split(' ')
-      | rv::take(4)
-      | rv::transform([](auto&& word) {
-        return word | rv::take(3) | rv::transform([](char c){ return std::tolower(c); });
-      })
-      | rv::join('-')
-      | ranges::to<std::string>;
-  // clang-format on
+  auto const the_title = title::create(title);
+  if (!the_title) {
+    return ""; // TODO: proper error handling
+  }
 
-  return id_prefix + "-0000000"s;
+  const auto issue_id = issue_id::generate(*the_title, fix::domain::description(description));
+  return issue_id.to_string();
 }
 
 size_t application_service::list() const { // NOLINT

src/domain/issue_id.cpp

@@ -0,0 +1,29 @@
+#include "issue_id.hpp"
+
+#include <range/v3/range/conversion.hpp>
+#include <range/v3/view.hpp>
+
+using namespace fix::domain;
+using namespace std::literals;
+namespace rv = ranges::views;
+
+issue_id::issue_id(std::string text) : text{std::move(text)} {}
+
+issue_id issue_id::generate(title const& title, description const& description) {
+  (void)description;
+  // clang-format off
+  const auto id_prefix = title.to_string()
+      | rv::split(' ')
+      | rv::take(4)
+      | rv::transform([](auto&& word) {
+        return word | rv::take(3) | rv::transform([](char c){ return std::tolower(c); });
+      })
+      | rv::join('-')
+      | ranges::to<std::string>;
+  // clang-format on
+  return issue_id{id_prefix + "-0000000"s};
+}
+
+std::string const& issue_id::to_string() const {
+  return text;
+}

src/domain/issue_id.hpp

@@ -0,0 +1,30 @@
+#ifndef FIX_SRC_DOMAIN_ISSUE_ID_HPP
+#define FIX_SRC_DOMAIN_ISSUE_ID_HPP
+
+#include "description.hpp"
+#include "title.hpp"
+
+namespace fix::domain {
+
+class issue_id {
+  std::string text;
+
+  explicit issue_id(std::string text);
+
+public:
+  //  move-only; rule of 5
+  issue_id(issue_id const&) = delete;
+  issue_id(issue_id&&) = default;
+  issue_id& operator=(issue_id const&) = delete;
+  issue_id& operator=(issue_id&&) = default;
+  ~issue_id() = default;
+
+  static issue_id generate(title const& title, description const& description);
+
+  // cppcheck-suppress functionStatic
+  std::string const& to_string() const;
+};
+
+} // namespace fix::domain
+
+#endif // FIX_SRC_DOMAIN_ISSUE_ID_HPP

src/domain/title.cpp

@@ -28,7 +28,7 @@ expected<title> title::create(std::string_view text) {
   // clang-format on
 }
 
-std::string title::to_string() const {
+std::string const& title::to_string() const {
   return text;
 }
 

src/domain/title.hpp

@@ -17,7 +17,7 @@ class title {
 public:
   static expected<title> create(std::string_view text);
 
-  std::string to_string() const;
+  std::string const& to_string() const;
 };
 
 } // namespace fix::domain

test/domain/CMakeLists.txt

@@ -2,6 +2,7 @@ set(DOMAIN_TEST_SOURCES
     application_service_test.cpp
     description_test.cpp
     domain_error_test.cpp
+    issue_id_test.cpp
     title_test.cpp
     )
 

test/domain/issue_id_test.cpp

@@ -0,0 +1,30 @@
+#include <catch2/catch.hpp>
+
+#include "issue_id.hpp"
+
+#include <string>
+
+#include "description.hpp"
+#include "title.hpp"
+
+using namespace fix::domain;
+using namespace std::literals;
+
+TEST_CASE("Issue IDs can be moved, but not default-constructed or copied") {
+  STATIC_REQUIRE(std::is_move_constructible_v<issue_id>);
+
+  STATIC_REQUIRE_FALSE(std::is_copy_assignable_v<issue_id>);
+  STATIC_REQUIRE_FALSE(std::is_copy_constructible_v<issue_id>);
+  STATIC_REQUIRE_FALSE(std::is_default_constructible_v<issue_id>);
+}
+
+TEST_CASE("Issue ID is contains abbreviated first words of the title") {
+  auto const& [the_title, the_description, id_prefix] = GENERATE(
+      std::tuple(title::create("this is a new issue"), description{"some text"}, "thi-is-a-new"),
+      std::tuple(title::create("My first issue in Fix"), description{"Dorem Fixum dolor sit amet"}, "my-fir-iss-in"));
+
+  REQUIRE(the_title);
+
+  auto const id_pattern = id_prefix + "-[0-9a-f]{7}"s;
+  CHECK_THAT(issue_id::generate(the_title.value(), the_description).to_string(), Catch::Matches(id_pattern));
+}