[FEAT] Add all test intersections

tests/05_rays.cpp

@@ -150,7 +150,7 @@ TEST_CASE("[05][Rays] Aggregating intersections", "[Intersections]")
     Sphere s;
     Intersection i1(1, s);
     Intersection i2(2, s);
-    Intersections xs = Intersections(i1, i2);
+    Intersections xs = Intersections({i1, i2});
 
     REQUIRE(xs.count() == 2);
     REQUIRE(xs[0].distance_t() == 1);
@@ -169,3 +169,61 @@ TEST_CASE("[05][Rays] Intersect set the object on the intersection", "[Intersect
     REQUIRE(xs[0].object() == s);
     REQUIRE(xs[1].object() == s);
 }
+
+/* ------------------------------------------------------------------------- */
+
+TEST_CASE("[05][Rays] The hit, when all intersections have positive t", "[Intersections]")
+{
+    Sphere s;
+    Intersection i1(1, s);
+    Intersection i2(2, s);
+    Intersections xs = Intersections({i2, i1});
+
+    Intersection i = xs.hit();
+
+    REQUIRE(i == i1);
+}
+
+/* ------------------------------------------------------------------------- */
+
+TEST_CASE("[05][Rays] The hit, when some intersections have negative t", "[Intersections]")
+{
+    Sphere s;
+    Intersection i1(-1, s);
+    Intersection i2(1, s);
+    Intersections xs = Intersections({i2, i1});
+
+    Intersection i = xs.hit();
+
+    REQUIRE(i == i2);
+}
+
+/* ------------------------------------------------------------------------- */
+
+TEST_CASE("[05][Rays] The hit, when all intersections have negative t", "[Intersections]")
+{
+    Sphere s;
+    Intersection i1(-2, s);
+    Intersection i2(-1, s);
+    Intersections xs = Intersections({i1, i2});
+
+    Intersection i = xs.hit();
+
+    REQUIRE(i.object().is_nothing());
+}
+
+/* ------------------------------------------------------------------------- */
+
+TEST_CASE("[05][Rays] The hit is always the lowest nonnegative intersection", "[Intersections]")
+{
+    Sphere s;
+    Intersection i1(5, s);
+    Intersection i2(7, s);
+    Intersection i3(-3, s);
+    Intersection i4(2, s);
+    Intersections xs = Intersections({i1, i2, i3, i4});
+
+    Intersection i = xs.hit();
+
+    REQUIRE(i == i4);
+}