Add NeoVim test runner

For the queries that can't be tested with `tree-sitter` itself.

Makefile

@@ -5,10 +5,12 @@ all:
 .PHONY: test
 test: all
 	tree-sitter test --apply-all-captures
+	nvim-test-runner
 
 .PHONY: update-tests
 update-tests: all
 	tree-sitter test -u --apply-all-captures
+	nvim-test-runner
 
 .PHONY: playground
 playground:

flake.nix

@@ -37,6 +37,7 @@
     }:
     let
       inherit (flake-utils.lib) eachDefaultSystem;
+      inherit (nixpkgs) lib;
     in
     eachDefaultSystem
       (system:
@@ -46,6 +47,25 @@
           overlays = [ self.overlays.default ];
         };
 
+        nvim-test-runner = pkgs.writeShellApplication {
+          name = "nvim-test-runner";
+
+          runtimeInputs = with pkgs; [
+            highlight-assertions
+            neovim
+          ];
+
+          text = ''
+            export NVIM_PLENARY='${pkgs.vimPlugins.plenary-nvim}'
+            export NVIM_TREESITTER='${pkgs.vimPlugins.nvim-treesitter}'
+            export NVIM_TREESITTER_TEXTOBJECTS='${pkgs.vimPlugins.nvim-treesitter-textobjects}'
+            export NVIM_TREESITTER_PARSER='${pkgs.vimPlugins.nvim-treesitter.grammarToPlugin self.packages.${system}.tree-sitter-bp}'
+
+            nvim --headless --noplugin -u ${scripts/minimal_init.lua} \
+                -c "PlenaryBustedDirectory test/ { minimal_init = '${./scripts/minimal_init.lua}' }"
+          '';
+        };
+
         bump-version = pkgs.writeShellScriptBin "bump-version" ''
           set -eu
 
@@ -90,6 +110,13 @@
                 enable = true;
               };
 
+              nvim-test-runner = {
+                enable = true;
+                name = "nvim tests";
+                entry = "${lib.getExe nvim-test-runner}";
+                pass_filenames = false;
+              };
+
               tree-sitter = {
                 enable = true;
                 name = "tree-sitter tests";
@@ -112,6 +139,7 @@
             nativeBuildInputs = with pkgs; [
               bump-version
               nodejs
+              nvim-test-runner
               # FIXME: waiting on #301336
               # (tree-sitter.override { webUISupport = true; })
               tree-sitter

scripts/dummy_plugin/queries/bp

@@ -0,0 +1 @@
+../../../queries

scripts/minimal_init.lua

@@ -0,0 +1,40 @@
+vim.opt.runtimepath:append(vim.env.NVIM_PLENARY)
+vim.opt.runtimepath:append(vim.env.NVIM_TREESITTER)
+vim.opt.runtimepath:append(vim.env.NVIM_TREESITTER_TEXTOBJECTS)
+vim.opt.runtimepath:append(vim.env.NVIM_TREESITTER_PARSER)
+
+vim.cmd.runtime({ "plugin/plenary.vim", bang = true })
+vim.cmd.runtime({ "plugin/nvim-treesitter.lua", bang = true })
+vim.cmd.runtime({ "plugin/nvim-treesitter-textobjects.lua", bang = true })
+
+local Path = require("plenary.path")
+
+local project_root =  Path:new(".") -- FIXME: relies on current working directory
+
+vim.filetype.add({
+  extension = {
+    bp = "bp",
+  },
+})
+
+vim.o.swapfile = false
+vim.bo.swapfile = false
+
+local parser_config = require("nvim-treesitter.parsers").get_parser_configs()
+parser_config.bp = {
+  install_info = {
+    url = project_root.filename,
+    files = {"src/parser.c"},
+  },
+}
+
+require("nvim-treesitter.configs").setup({
+  indent = { enable = true },
+  highlight = { enable = true },
+})
+
+-- We need a hierarchy of `queries/bp/*.scm` in the runtimepath, otherwise
+-- `nvim-treesitter` doesn't enable some of its features (e.g: folding).
+-- The dummy plugin has a symlink following that format for our queries.
+local dummy_plugin_path = project_root / "scripts" / "dummy_plugin"
+vim.opt.runtimepath:append(dummy_plugin_path.filename)