tests: [WIP] add unit tests for some of the instructions

Signed-off-by: Amneesh Singh <natto@weirdnatto.in>

nix/catch2.nix

@@ -0,0 +1,17 @@
+{ stdenv, fetchFromGitHub, meson, ninja }:
+
+stdenv.mkDerivation rec {
+  name = "catch2";
+  version = "3.4.0";
+
+  src = fetchFromGitHub {
+    owner = "catchorg";
+    repo = "Catch2";
+    rev = "v${version}";
+    sha256 = "sha256-DqGGfNjKPW9HFJrX9arFHyNYjB61uoL6NabZatTWrr0=";
+  };
+
+  nativeBuildInputs = [ meson ninja ];
+
+  outputs = [ "out" "dev" ];
+}