prismlauncher: add module

tests/modules/programs/prismlauncher/default.nix

@@ -0,0 +1,3 @@
+{
+  prismlauncher-settings = ./settings.nix;
+}

tests/modules/programs/prismlauncher/settings.nix

@@ -0,0 +1,65 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+let
+  configPath = ".local/share/PrismLauncher/prismlauncher.cfg";
+
+  preexistingConfig = pkgs.writeText "preexisting.cfg" ''
+    [General]
+    ApplicationTheme=system
+    MaxMemAlloc=8192
+    MinMemAlloc=512
+  '';
+
+  expectedConfig = pkgs.writeText "expected.cfg" ''
+    [General]
+    ApplicationTheme=dark
+    MaxMemAlloc=8192
+    MinMemAlloc=512
+    ConsoleMaxLines=100000
+    ShowConsole=true
+  '';
+
+  activationScript = pkgs.writeScript "activation" config.home.activation.prismlauncherConfigActivation.data;
+in
+
+{
+  programs.prismlauncher = {
+    enable = true;
+    package = config.lib.test.mkStubPackage { };
+
+    settings = {
+      ApplicationTheme = "dark";
+      ShowConsole = true;
+      ConsoleMaxLines = 100000;
+    };
+  };
+
+  home.homeDirectory = lib.mkForce "/@TMPDIR@/hm-user";
+
+  nmt.script = ''
+    export HOME=$TMPDIR/hm-user
+
+    # write preexisting config
+    mkdir -p $HOME/.local/share/PrismLauncher
+    cat ${preexistingConfig} > $HOME/${configPath}
+
+    # run the activation script
+    substitute ${activationScript} $TMPDIR/activate --subst-var TMPDIR
+    chmod +x $TMPDIR/activate
+    $TMPDIR/activate
+
+    # validate the merged config
+    assertFileExists "$HOME/${configPath}"
+    assertFileContent "$HOME/${configPath}" "${expectedConfig}"
+
+    # test idempotence
+    $TMPDIR/activate
+    assertFileExists "$HOME/${configPath}"
+    assertFileContent "$HOME/${configPath}" "${expectedConfig}"
+  '';
+}