Add expansion.nix

Author: Damon Chen

integration_tests/shell.nix

@@ -19,5 +19,6 @@ pkgs.mkShell {
     (import ../nix/testenv.nix { inherit pkgs; })
     (import ../nix/chainmain.nix { inherit pkgs; })
     (import ../nix/hermes.nix { inherit pkgs; })
+    (import ../nix/expansion.nix { inherit pkgs; })
   ];
 }

nix/expansion.nix

@@ -0,0 +1,18 @@
+{ pkgs }:
+let
+  project_root = builtins.toString ../integration_tests;
+  dotenv = builtins.path { name = "dotenv"; path = ../scripts/.env; };
+  expansion = builtins.toString ../integration_tests/expansion.py;
+in with pkgs;
+stdenv.mkDerivation {
+  name = "expansion";
+  buildInputs = [
+    (import ../nix/testenv.nix { inherit pkgs; })
+  ];
+  buildCommand = ''
+    mkdir -p $out
+    cp ${dotenv} $out
+    cd ${project_root}
+    python ${expansion}
+  '';
+}