Add substituter install test

nix/tests/vm-test/default.nix

@@ -132,6 +132,33 @@ let
         fi
       '';
     };
+    install-substituter = pkgs: let
+      rootPaths = binaryTarball.${pkgs.system}.passthru.rootPaths;
+      binaryCache = pkgs.mkBinaryCache { inherit rootPaths; };
+      targetArg = pkg: "--substitution-targets ${pkg.outPath}";
+      targetArgs = lib.concatMapStringsSep " " targetArg rootPaths;
+    in {
+      copyTarball = ''
+        scp -P 20022 $ssh_opts -r ${binaryCache} vagrant@localhost:binaryCache
+      '';
+      install = ''
+        python3 -m http.server -d binaryCache 8000 &
+        server_pid=$!
+        trap "kill $server_pid" EXIT
+        sleep 1
+        RUST_BACKTRACE="full" ./nix-installer install \
+            --use-substituters \
+            --substituters http://127.0.0.1:8000 \
+            --no-require-sigs \
+            ${targetArgs} \
+            --no-confirm \
+            --logger pretty \
+            --log-directive lix_installer=info
+      '';
+      check = installCases.install-default.check;
+      uninstall = installCases.install-default.uninstall;
+      uninstallCheck = installCases.install-default.uninstallCheck;
+    };
     install-no-start-daemon = {
       install = ''
         NIX_PATH=$(readlink -f nix.tar.xz)
@@ -500,9 +527,13 @@ let
 
   };
 
-  makeTest = imageName: testName: test:
-    let image = images.${imageName}; in
-    with (forSystem image.system ({ system, pkgs, ... }: pkgs));
+  makeTest = imageName: testName: testFunc:
+    let 
+      image = images.${imageName};
+      pkgs = (forSystem image.system ({ system, pkgs, ... }: pkgs));
+      test = if builtins.isFunction testFunc then (testFunc pkgs) else testFunc;
+    in
+    with pkgs;
     runCommand
       "installer-test-${imageName}-${testName}"
       {
@@ -517,6 +548,8 @@ let
         uninstallCheckScript = test.uninstallCheck;
         installer = lix-installer-static;
         binaryTarball = binaryTarball.${system};
+        copyTarball = test.copyTarball
+          or "scp -P 20022 $ssh_opts $binaryTarball/lix-*.tar.xz vagrant@localhost:nix.tar.xz";
       }
       ''
         shopt -s nullglob
@@ -575,8 +608,9 @@ let
         echo "Copying installer..."
         scp -P 20022 $ssh_opts $installer/bin/lix-installer vagrant@localhost:nix-installer
 
+        ls $binaryTarball
         echo "Copying nix tarball..."
-        scp -P 20022 $ssh_opts $binaryTarball/lix-*.tar.xz vagrant@localhost:nix.tar.xz
+        eval "$copyTarball"
 
         echo "Running preinstall..."
         $ssh "set -eux; $preinstallScript"