[ADD] add a skeleton of the group and refactor some test datas.

tests/14_groups.cpp

@@ -0,0 +1,66 @@
+/*!
+ * 14_groups.cpp
+ *
+ * Copyright (c) 2015-2024, NADAL Jean-Baptiste. All rights reserved.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301 USA
+ *
+ * @Author:  NADAL Jean-Baptiste
+ * @Date: 21/03/2024
+ *
+ */
+
+/*---------------------------------------------------------------------------*/
+
+#include <catch2/catch_test_macros.hpp>
+
+#include "raytracing.h"
+
+#include "common_data.h"
+
+using namespace Raytracer;
+
+/* ------------------------------------------------------------------------- */
+
+SCENARIO("Creating a new group", "[features/groups.feature]")
+{
+    GIVEN("g <- group()")
+    {
+        Group g;
+        THEN("g.transform = identity_matrix")
+        {
+            REQUIRE(g.transform() == Matrix::identity());
+        }
+        AND_THEN("g is empty")
+        {
+            REQUIRE(g.is_empty() == true);
+        }
+    }
+}
+
+/* ------------------------------------------------------------------------- */
+
+SCENARIO("A shape has a parent attribute", "[features/shapes.feature]")
+{
+    GIVEN("s <- test_shape()")
+    {
+        TestShape s;
+        THEN("s.parent is nothing")
+        {
+            REQUIRE(s.parent() == nullptr);
+        }
+    }
+}