Boundingboxes should be ready.

Next step (later) would be to properly use them other than group to lower the number of intersection calculation per ray.

tests/sphere_test.cpp

@@ -218,4 +218,11 @@ TEST(SphereTest, The_bounding_box_of_a_sphere)
 
     ASSERT_EQ(res.min, b.min);
     ASSERT_EQ(res.max, b.max);
+}
+
+TEST(SphereTest, A_sphere_have_finite_bounds)
+{
+    Sphere t = Sphere();
+
+    ASSERT_TRUE(t.haveFiniteBounds());
 }