Add test for using range to concat const collections

This commit is added in order to test the fix from the previous commit,
because it is good to test things.

Author: thomasspriggs

unit/util/range.cpp

@@ -76,6 +76,18 @@ SCENARIO("range tests", "[core][util][range]")
       REQUIRE(odds == expected_odds);
     }
   }
+  GIVEN("Two const vectors of ints")
+  {
+    const std::vector<int> input1{1, 2};
+    const std::vector<int> input2{3, 4};
+    THEN("Concat the vectors using range.")
+    {
+      auto range = make_range(input1).concat(make_range(input2));
+      const std::vector<int> output{range.begin(), range.end()};
+      const std::vector<int> expected{1, 2, 3, 4};
+      REQUIRE(output == expected);
+    };
+  }
 }
 
 class move_onlyt