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

tests/10_patterns.cpp

@@ -29,23 +29,12 @@
 
 #include "raytracing.h"
 
+#include "common_data.h"
+
 using namespace Raytracer;
 
 /* ------------------------------------------------------------------------- */
 
-class TestPattern : public Pattern
-{
-public:
-    TestPattern(void) = default;
-
-    const Color pattern_at(const Tuple &a_point) const override
-    {
-        return Color(a_point.x(), a_point.y(), a_point.z());
-    }
-};
-
-/* ------------------------------------------------------------------------- */
-
 SCENARIO("Creating a stripe pattern", "[features/patterns.feature]")
 {
     GIVEN("pattern <- stripe_pattern(white, black)")