Fix the nixproc-generate-config tool, create a basic testcase for it

nixproc/create-managed-process/agnostic/create-managed-process-from-config.nix

@@ -12,7 +12,7 @@ let
   createManagedProcessFromConfig = configFile:
     let
       createManagedProcess = import ./create-managed-process-universal.nix {
-        inherit pkgs runtimeDir tmpDir forceDisableUserChange processManager;
+        inherit pkgs stateDir runtimeDir tmpDir forceDisableUserChange processManager;
       };
 
       properties = builtins.fromJSON (builtins.readFile configFile);

tests/webapps-agnostic-config.nix

@@ -0,0 +1,70 @@
+{nixpkgs ? <nixpkgs>}:
+
+with import "${nixpkgs}/nixos/lib/testing-python.nix" { system = builtins.currentSystem; };
+
+let
+  webappUnprivilegedAutoModeConfig = (import ../examples/webapps-agnostic/processes.nix {
+    forceDisableUserChange = true;
+    processManager = null;
+    webappMode = null;
+  }).webapp.pkg;
+
+  webappUnprivilegedAutoModeSysvinit = (import ../examples/webapps-agnostic/processes.nix {
+    forceDisableUserChange = true;
+    processManager = "sysvinit";
+    webappMode = null;
+  }).webapp.pkg;
+
+  tools = import ../tools {};
+
+  nix-processmgmt = ./..;
+
+  env = "NIX_PATH=nixpkgs=${nixpkgs}";
+in
+makeTest {
+  machine =
+    {pkgs, ...}:
+
+    {
+      virtualisation.pathsInNixDB = [ pkgs.stdenv ] ++ pkgs.coreutils.all ++ [
+        webappUnprivilegedAutoModeConfig
+        webappUnprivilegedAutoModeSysvinit
+      ];
+
+      virtualisation.writableStore = true;
+
+      # We can't download any substitutes in a test environment. To make tests
+      # faster, we disable substitutes so that Nix does not waste any time by
+      # attempting to download them.
+      nix.extraOptions = ''
+        substitute = false
+      '';
+
+      environment.systemPackages = [
+        pkgs.stdenv
+        pkgs.dysnomia
+        tools.build
+        tools.generate-config
+        tools.sysvinit
+      ];
+    };
+
+  testScript = ''
+    start_all()
+
+    # Make sure the unprivileged user can deploy
+    machine.succeed("mkdir -p var/run var/tmp")
+
+    result = machine.succeed(
+        "cat ${webappUnprivilegedAutoModeConfig}/webapp.json >&2"
+    )
+
+    result = machine.succeed(
+        "${env} nixproc-generate-config --process-manager sysvinit --force-disable-user-change ${webappUnprivilegedAutoModeConfig}/webapp.json"
+    )
+
+    machine.succeed("{}/etc/rc.d/init.d/webapp start".format(result[:-1]))
+    machine.succeed("pgrep -f '/bin/webapp -D$'")
+    machine.succeed("curl --fail http://localhost:5000 | grep 'Simple test webapp'")
+  '';
+}

tools/generate-config/nixproc-generate-config.in

@@ -70,7 +70,7 @@ do
             tmpDirArg="--tmp-dir $2"
             ;;
         --force-disable-user-change)
-            forceDisableUserChangeArg="--force-disable-user-change"
+            forceDisableUserChangeArg="--arg forceDisableUserChange true"
             ;;
         --no-out-link)
             noOutLinkArg="--no-out-link"