numbat: Add initFile option

modules/programs/numbat.nix

@@ -38,11 +38,26 @@ in
         <https://numbat.dev/doc/cli-customization.html#configuration> for options.
       '';
     };
+
+    initFile = lib.mkOption {
+      type = lib.types.nullOr lib.types.lines;
+      default = null;
+      example = ''
+        unit kohm: ElectricResistance = kV/A
+      '';
+      description = ''
+        User initialization file ({file}`init.nbt`) contents.
+      '';
+    };
   };
 
   config = mkIf cfg.enable {
     home.packages = mkIf (cfg.package != null) [ cfg.package ];
 
+    home.file."${configDir}/init.nbt" = mkIf (cfg.initFile != null) {
+      text = cfg.initFile;
+    };
+
     home.file."${configDir}/config.toml" = mkIf (cfg.settings != { }) {
       source = tomlFormat.generate "numbat-config" cfg.settings;
     };

tests/modules/programs/numbat/empty-config.nix

@@ -14,5 +14,6 @@ in
 
   nmt.script = ''
     assertPathNotExists 'home-files/${configDir}/config.toml'
+    assertPathNotExists 'home-files/${configDir}/init.nbt'
   '';
 }

tests/modules/programs/numbat/example-config.nix

@@ -19,6 +19,9 @@ in
       prompt = "> ";
       exchange-rates.fetching-policy = "on-first-use";
     };
+    initFile = ''
+      unit kohm: ElectricResistance = kV/A
+    '';
   };
 
   nmt.script = ''
@@ -31,5 +34,10 @@ in
         [exchange-rates]
         fetching-policy = "on-first-use"
       ''}
+    assertFileExists 'home-files/${configDir}/init.nbt'
+    assertFileContent $(normalizeStorePaths 'home-files/${configDir}/init.nbt') \
+      ${builtins.toFile "expected-init.nbt" ''
+        unit kohm: ElectricResistance = kV/A
+      ''}
   '';
 }