Now have more test for the base functionality but need to push render tests and find a way to test the GUI. I've also brought in sol2 for lua integration but not sure what to do with it.

tests/render.cpp

@@ -0,0 +1,38 @@
+#include <catch2/catch_test_macros.hpp>
+#include <fmt/core.h>
+#include "render.hpp"
+#include "panel.hpp"
+
+using namespace ftxui;
+using namespace fmt;
+using std::string;
+
+void run_renderer(SFMLRender &renderer, Panel &panel) {
+  panel.render();
+  renderer.display();
+  REQUIRE(renderer.is_open() == true);
+  renderer.clear();
+  renderer.draw(panel);
+}
+
+TEST_CASE("can render a text or grid panel", "[render]") {
+  SFMLRender renderer;
+
+  Panel panel(0, 0, 20, 5);
+  Panel grid(200, 200, 20, 5, true);
+
+  auto text_box = Renderer([]{
+      return hbox({
+        hflow(
+            vbox(text("I AM TEXT"))
+        )});
+    });
+
+  panel.set_renderer(text_box);
+  grid.set_renderer(text_box);
+
+  run_renderer(renderer, panel);
+  run_renderer(renderer, grid);
+
+  renderer.close();
+}