plugins/lsp-format: add plugin + test

plugins/default.nix

@@ -48,6 +48,7 @@
     ./lsp
     ./lsp/inc-rename.nix
     ./lsp/lspsaga.nix
+    ./lsp/lsp-format.nix
     ./lsp/lsp-lines.nix
     ./lsp/nvim-lightbulb.nix
     ./lsp/trouble.nix

plugins/lsp/helpers.nix

@@ -68,7 +68,7 @@
                 };
 
                 function = mkOption {
-                  type = types.str;
+                  type = types.lines;
                   description = ''
                     Body of the on_attach function.
                     The argument `client` and `bufnr` is provided.

plugins/lsp/lsp-format.nix

@@ -0,0 +1,117 @@
+{
+  pkgs,
+  lib,
+  config,
+  ...
+}:
+with lib; let
+  cfg = config.plugins.lsp-format;
+  helpers = import ../helpers.nix {inherit lib;};
+in {
+  options.plugins.lsp-format =
+    helpers.extraOptionsOptions
+    // {
+      enable = mkEnableOption "lsp-format.nvim";
+
+      package = helpers.mkPackageOption "lsp-format.nvim" pkgs.vimPlugins.lsp-format-nvim;
+
+      setup = mkOption {
+        type = with types;
+          attrsOf
+          (submodule {
+            # Allow the user to provide other options
+            freeformType = types.attrs;
+
+            options = {
+              exclude =
+                helpers.mkNullOrOption (listOf str)
+                "List of client names to exclude from formatting.";
+
+              order =
+                helpers.mkNullOrOption (listOf str)
+                ''
+                  List of client names. Formatting is requested from clients in the following
+                  order: first all clients that are not in the `order` table, then the remaining
+                  clients in the order as they occur in the `order` table.
+                  (same logic as |vim.lsp.buf.formatting_seq_sync()|).
+                '';
+
+              sync = helpers.defaultNullOpts.mkBool false ''
+                Whether to turn on synchronous formatting.
+                The editor will block until formatting is done.
+              '';
+
+              force = helpers.defaultNullOpts.mkBool false ''
+                If true, the format result will always be written to the buffer, even if the
+                buffer changed.
+              '';
+            };
+          });
+        description = "The setup option maps |filetypes| to format options.";
+        example = {
+          gopls = {
+            exclude = ["gopls"];
+            order = ["gopls" "efm"];
+            sync = true;
+            force = true;
+          };
+        };
+        default = {};
+      };
+
+      lspServersToEnable = mkOption {
+        type = with types; either (enum ["none" "all"]) (listOf str);
+        default = "all";
+        description = ''
+          Choose the LSP servers for which lsp-format should be enabled.
+
+          Possible values:
+          - "all" (default): Enable formatting for all language servers
+          - "none": Do not enable formatting on any language server.
+            You might choose this if for some reason you want to manually call
+            `require("lsp-format").on_attach(client)` in the `onAttach` function of your language
+            servers.
+          - list of LS names: Manually choose the servers by name
+        '';
+        example = [
+          "efm"
+          "gopls"
+        ];
+      };
+    };
+
+  config = let
+    setupOptions = cfg.setup // cfg.extraOptions;
+  in
+    mkIf cfg.enable {
+      warnings = mkIf (!config.plugins.lsp.enable) [
+        "You have enabled `plugins.lsp-format` but have `plugins.lsp` disabled."
+      ];
+
+      extraPlugins = [cfg.package];
+
+      plugins.lsp = {
+        onAttach = mkIf (cfg.lspServersToEnable == "all") ''
+          require("lsp-format").on_attach(client)
+        '';
+
+        servers =
+          if (isList cfg.lspServersToEnable)
+          then
+            genAttrs
+            cfg.lspServersToEnable
+            (
+              serverName: {
+                onAttach.function = ''
+                  require("lsp-format").on_attach(client)
+                '';
+              }
+            )
+          else {};
+      };
+
+      extraConfigLua = ''
+        require("lsp-format").setup(${helpers.toLuaObject setupOptions})
+      '';
+    };
+}

tests/test-sources/plugins/lsp/lsp-format.nix

@@ -0,0 +1,37 @@
+{
+  empty = {
+    plugins.lsp.enable = true;
+    plugins.lsp-format.enable = true;
+  };
+
+  example = {
+    plugins = {
+      lsp = {
+        enable = true;
+
+        servers.gopls = {
+          enable = true;
+          onAttach.function = ''
+            x = 12
+          '';
+        };
+      };
+
+      lsp-format = {
+        enable = true;
+
+        setup = {
+          gopls = {
+            exclude = ["gopls"];
+            order = ["gopls" "efm"];
+            sync = true;
+            force = true;
+
+            # Test the ability to provide extra options for each filetype
+            someRandomOption = 42;
+          };
+        };
+      };
+    };
+  };
+}