Background

I use Neovim (btw!) and Nix (btw btw!!!). I mean, half the reason to use these tools is to tell other people you use them, right? 😉 Otherwise, why would I go through the pain I experienced today? “What pain?” you ask. Good question!

A few weeks ago, I noticed that running tests in Neovim was failing with a no test found error. I’m using neotest and neotest-golang to run tests within Neovim.

Here’s a link to my config.

I’m also using the nightly build of Neovim, so getting the latest version isn’t great if you want stability. Things can break at any moment, like running tests. Anyway, today (November 1st), I had some free time and decided to spend most of the day fixing this issue. poświęcenie

Setup

I’m using NixOS (should I do another “btw” joke??? 🤔), so I want to manage all my dependencies with Nix. I’m also using NixCats, which allows me to configure Neovim with Lua but package it with Nix (it has a few other features I don’t really use, but others might).

One of the nice features of NixCats is that we can easily add Neovim plugins that aren’t in nixpkgs using our flake inputs:

plugins-neotest-golang = {
  url = "github:fredrikaverpil/neotest-golang";
  flake = false;
};

We just need to add plugins-x, and then we can reference it in our NixCats config like pkgs.neovimPlugins.neotest-golang. It’s tied to my flake, so I can just run nix flake update to update those Neovim plugins along with every other input. Then I upgrade my setup, as you might with apt upgrade, but with nh os switch or nh home switch.

Debugging 🐛

This setup means I can use the latest version of this plugin (v2.5.0 at the time of writing), but even upgrading to the latest version wasn’t enough. I probably shouldn’t have tied it to the main branch. 😅

I found this issue, which made me think I should try the latest version.

After a lot of (wasted) debugging, I finally read the migration guide. An amateur mistake, I know. 🤦

nvim-treesitter

It turns out I need to use nvim-treesitter, but the main branch, not the master branch, which is frozen and no longer under development. There’s an existing overlay we can use so we don’t have to change how we install our dependencies.

Like so:

nvim-treesitter-main = {
  url = "github:iofq/nvim-treesitter-main";
  inputs.nixpkgs.follows = "nixpkgs";
};

I’m also using snowfall-lib, so I can add a new overlay like so in my flake.nix:

overlays = with inputs; [
    # ...
    nvim-treesitter-main.overlays.default
];

I also created a new overlay file, overlays/nvim-treesitter-main/default.nix:

inputs: final: prev: {
  vimPlugins = prev.vimPlugins // {
    nvim-treesitter = prev.vimPlugins.nvim-treesitter.withAllGrammars;
    nvim-treesitter-textobjects = prev.vimPlugins.nvim-treesitter-textobjects.overrideAttrs (old: {
      dependencies = with prev.vimPlugins; [ nvim-treesitter ];
    });
  };
}

You can also add the cache to save some time rebuilding all the grammars on your own machine:

trusted-substituters = [
  "https://nvim-treesitter-main.cachix.org"
];

Then, in my Neovim config, I updated the setup to look like this:

require("nvim-treesitter").setup()

After this, when I opened a Markdown document, I noticed it was all white. But using InspectTree, the AST looked correct. It seemed like highlighting wasn’t working, which, again, if I had read the docs, I would’ve seen that I need to create an autocommand.

vim.api.nvim_create_autocmd("FileType", {
	pattern = "*",
	callback = function(args)
		-- Add error handling to prevent crashes during session restore
		local success, err = pcall(function()
			-- Check if parser is available before starting
			local lang = vim.bo[args.buf].filetype
			local ts_lang = vim.treesitter.language.get_lang(lang)
			if ts_lang then
				vim.treesitter.start(args.buf)
			end
		end)
		if not success then
			-- Silently fail if treesitter can't start for this buffer
			vim.notify("Treesitter failed to start for " .. vim.bo[args.buf].filetype .. ": " .. err, vim.log.levels.DEBUG)
		end
	end,
})

textobjects

To set up textobjects, we need to set up the plugin separately as well, also using the main branch. It now looks something like this:

require("nvim-treesitter-textobjects").setup({
    select = {
        lookahead = true,
        selection_modes = {
            ["@parameter.outer"] = "v",
            ["@function.outer"] = "V",
            ["@class.outer"] = "<c-v>",
        },
        include_surrounding_whitespace = false,
    },
    move = {
        set_jumps = true,
    },
})

-- Set up select keymaps using the new API
vim.keymap.set({ "x", "o" }, "af", function()
    require("nvim-treesitter-textobjects.select").select_textobject("@function.outer", "textobjects")
end)
vim.keymap.set({ "x", "o" }, "if", function()
    require("nvim-treesitter-textobjects.select").select_textobject("@function.inner", "textobjects")
end)
vim.keymap.set({ "x", "o" }, "ac", function()
    require("nvim-treesitter-textobjects.select").select_textobject("@class.outer", "textobjects")
end)

Notice how we now set up the textobjects as keybindings. Then, for swap and repeatable, assuming you were using those, it looks something like this:

vim.keymap.set("n", "<leader>a", function()
    require("nvim-treesitter-textobjects.swap").swap_next("@parameter.inner")
end)
vim.keymap.set("n", "<leader>A", function()
    require("nvim-treesitter-textobjects.swap").swap_previous("@parameter.outer")
end)

local ts_repeat_ok, ts_repeat_move = pcall(require, "nvim-treesitter-textobjects.repeatable_move")
if ts_repeat_ok then
    vim.keymap.set({ "n", "x", "o" }, ";", ts_repeat_move.repeat_last_move_next)
    vim.keymap.set({ "n", "x", "o" }, ",", ts_repeat_move.repeat_last_move_previous)
    vim.keymap.set({ "n", "x", "o" }, "f", ts_repeat_move.builtin_f_expr, { expr = true })
    vim.keymap.set({ "n", "x", "o" }, "F", ts_repeat_move.builtin_F_expr, { expr = true })
    vim.keymap.set({ "n", "x", "o" }, "t", ts_repeat_move.builtin_t_expr, { expr = true })
    vim.keymap.set({ "n", "x", "o" }, "T", ts_repeat_move.builtin_T_expr, { expr = true })
end

incremental selection

You can now do this via the LSP instead of the textobjects plugin, so I added the following plugins:

vim.keymap.set("x", "<c-space>", function()
    vim.lsp.buf.selection_range("outer")
end, { desc = "Expand selection (incremental)" })

vim.keymap.set("x", "<M-space>", function()
    vim.lsp.buf.selection_range("inner")
end, { desc = "Shrink selection (incremental)" })

vim.keymap.set("n", "<c-space>", function()
    vim.cmd("normal! v")
    vim.lsp.buf.selection_range("outer")
end, { desc = "Start incremental selection" })

vim.keymap.set("x", "<c-s>", function()
    vim.lsp.buf.selection_range("outer")
end, { desc = "Expand to scope" })

Neotest

I thought that would be enough, but I noticed in my ~/.local/state/nvim/neotest.log that I was getting the following error:

WARN | 2025-11-01T20:10:40Z+0000 | ...eovimPackages/opt/neotest/lua/neotest/lib/subprocess.lua:203 | CHILD | Error in remote call ...Packages/opt/neotest/lua/neotest/lib/treesitter/init.lua:130: attempt to index a nil value
stack traceback:
    ...Packages/opt/neotest/lua/neotest/lib/treesitter/init.lua:130: in function 'get__parse_root'
    ...Packages/opt/neotest/lua/neotest/lib/treesitter/init.lua:162: in function 'parse_positions_from_string'
    ...Packages/opt/neotest/lua/neotest/lib/treesitter/init.lua:209: in function 'func'
    ...eovimPackages/opt/neotest/lua/neotest/lib/subprocess.lua:195: in function <...eovimPackages/opt/neotest/lua/neotest/lib/subprocess.lua:194>
    [C]: in function 'xpcall'
    ...eovimPackages/opt/neotest/lua/neotest/lib/subprocess.lua:194: in function <...eovimPackages/opt/neotest/lua/neotest/lib/subprocess.lua:193>
WARN | 2025-11-01T20:10:40Z+0000 | ...eovimPackages/opt/neotest/lua/neotest/lib/subprocess.lua:203 | CHILD | Error in remote call ...Packages/opt/neotest/lua/neotest/lib/treesitter/init.lua:130: attempt to index a nil val

I found this issue and this fix. Then I updated Neotest to the latest version by again adding it as an input:

plugins-neotest = {
  url = "github:nvim-neotest/neotest";
  flake = false;
};

and

test = with pkgs.vimPlugins; [
  pkgs.neovimPlugins.neotest
];

Finally fixed? 🙏

Then I ran nh home switch (similar to home-manager switch --flake ~/nixicle#haseeb@workstation). I reloaded Neovim, and voila, it works now! That was my day of yak shaving and fixing random broken stuff. 🐐

I guess it goes without saying that if you’re running on the bleeding edge, things will break. The advantage is that usually only one thing breaks at a time, whereas with a major upgrade, multiple things might break, and you have to fix them all at once.

Also, this classic video is a must-watch!!!! 🤣