bat: allow setting themes/syntaxes without IFD

The way the `bat` module is currently written makes it essentially
impossible to use themes and syntaxes without IFD, since you must
provide the contents as string, instead of just giving a path to be
linked.

With this change, setting themes/syntaxes by-string will start issuing
warnings, and a new attribute model is added, lightly inspired by how
`programs.zsh.plugins` avoided this issue.

tests/modules/programs/bat/bat.nix

@@ -13,11 +13,11 @@ with lib;
         map-syntax = [ "*.jenkinsfile:Groovy" "*.props:Java Properties" ];
       };
 
-      themes.testtheme = ''
+      themes.testtheme.src = pkgs.writeText "testtheme.tmTheme" ''
         This is a test theme.
       '';
 
-      syntaxes.testsyntax = ''
+      syntaxes.testsyntax.src = pkgs.writeText "testsyntax.sublime-syntax" ''
         This is a test syntax.
       '';
     };

tests/modules/programs/bat/default.nix

@@ -1 +1,4 @@
-{ bat = ./bat.nix; }
+{
+  bat = ./bat.nix;
+  bat-deprecated-options = ./deprecated-options.nix;
+}

tests/modules/programs/bat/deprecated-options.nix

@@ -0,0 +1,67 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+{
+  config = {
+    programs.bat = {
+      enable = true;
+
+      config = {
+        theme = "TwoDark";
+        pager = "less -FR";
+        map-syntax = [ "*.jenkinsfile:Groovy" "*.props:Java Properties" ];
+      };
+
+      themes.testtheme = ''
+        This is a test theme.
+      '';
+
+      syntaxes.testsyntax = ''
+        This is a test syntax.
+      '';
+    };
+
+    test.stubs.bat = { };
+
+    test.asserts.warnings.enable = true;
+    test.asserts.warnings.expected = [
+      ''
+        Using programs.bat.themes as a string option is deprecated and will be
+        removed in the future. Please change to using it as an attribute set
+        instead.
+      ''
+      ''
+        Using programs.bat.syntaxes as a string option is deprecated and will be
+        removed in the future. Please change to using it as an attribute set
+        instead.
+      ''
+    ];
+
+    nmt.script = ''
+      assertFileExists home-files/.config/bat/config
+      assertFileContent home-files/.config/bat/config ${
+        pkgs.writeText "bat.expected" ''
+          --map-syntax='*.jenkinsfile:Groovy'
+          --map-syntax='*.props:Java Properties'
+          --pager='less -FR'
+          --theme='TwoDark'
+        ''
+      }
+
+      assertFileExists home-files/.config/bat/themes/testtheme.tmTheme
+      assertFileContent home-files/.config/bat/themes/testtheme.tmTheme ${
+        pkgs.writeText "bat.expected" ''
+          This is a test theme.
+        ''
+      }
+
+      assertFileExists home-files/.config/bat/syntaxes/testsyntax.sublime-syntax
+      assertFileContent home-files/.config/bat/syntaxes/testsyntax.sublime-syntax ${
+        pkgs.writeText "bat.expected" ''
+          This is a test syntax.
+        ''
+      }
+    '';
+  };
+}