fix: do not generate a new id on update

source/d_webservice_example/dataaccess/in_memory_todo_repository.d

@@ -3,6 +3,11 @@ module d_webservice_example.dataaccess.in_memory_todo_repository;
 import aermicioi.aedi : component, qualifier;
 import d_webservice_example.business.todo_service : TodoRepository;
 
+version (unittest)
+{
+    import fluent.asserts;
+}
+
 @component @qualifier!TodoRepository() class InMemoryTodoRepository : TodoRepository
 {
     import d_webservice_example.model.todo : Todo;
@@ -15,11 +20,46 @@ private:
 public:
     override Todo save(Todo todo)
     {
-        todo.id = randomUUID.toString;
+        import std.range.primitives : empty;
+
+        if (todo.id.empty)
+            todo.id = randomUUID.toString;
         todos[todo.id] = todo;
         return todo;
     }
 
+    unittest
+    {
+        // given
+        auto underTest = new InMemoryTodoRepository;
+        auto todo = Todo("some title", "some content",
+                UUID("00000000-0000-0000-0000-000000000001"));
+
+        // when
+        auto savedTodo = underTest.save(todo);
+
+        // then
+        savedTodo.title.should.equal(todo.title);
+        savedTodo.content.should.equal(todo.content);
+        savedTodo.uuid.should.equal(todo.uuid);
+        savedTodo.id.length.should.equal(36);
+    }
+
+    unittest
+    {
+        // given
+        auto underTest = new InMemoryTodoRepository;
+        auto todo = Todo("some title", "some content",
+                UUID("00000000-0000-0000-0000-000000000001"),
+                "00000000-0000-0000-0000-000000000002");
+
+        // when
+        auto savedTodo = underTest.save(todo);
+
+        // then
+        savedTodo.should.equal(todo);
+    }
+
     override Todo[] findAll()
     {
         import std.array : array;

source/d_webservice_example/model/todo.d

@@ -18,6 +18,14 @@ struct Todo
         this.uuid = uuid;
     }
 
+    this(string title, string content, UUID uuid, string id) nothrow pure @safe @nogc
+    {
+        this.title = title;
+        this.content = content;
+        this.uuid = uuid;
+        this.id = id;
+    }
+
     string title;
     string content;