Meh I'll figure out submodules later

.config/nvim/pack/tree/start/nui.nvim/tests/init.lua

@@ -0,0 +1,24 @@
+-- mimic startup option `--clean`
+local function clean_startup()
+  for _, path in ipairs(vim.split(vim.o.runtimepath, ",")) do
+    if
+      string.find(path, vim.fn.expand("~/.config/nvim"))
+      or string.find(path, vim.fn.expand("~/.local/share/nvim/site"))
+    then
+      vim.opt.packpath:remove(path)
+      vim.opt.runtimepath:remove(path)
+    end
+  end
+end
+
+clean_startup()
+
+local root_dir = vim.fn.fnamemodify(vim.trim(vim.fn.system("git rev-parse --show-toplevel")), ":p"):gsub("/$", "")
+
+package.path = string.format("%s;%s/?.lua;%s/?/init.lua", package.path, root_dir, root_dir)
+
+vim.opt.packpath:prepend(root_dir .. "/.tests/site")
+
+vim.cmd([[
+  packadd plenary.nvim
+]])