add fine tuning and unit testing

tests/minimal_init.lua

@@ -0,0 +1,15 @@
+vim.cmd("set rtp^=.")
+
+local data_path = vim.fn.stdpath("data")
+local plenary_paths = {
+  data_path .. "/site/pack/packer/start/plenary.nvim",
+  data_path .. "/lazy/plenary.nvim",
+}
+
+for _, path in ipairs(plenary_paths) do
+  if vim.fn.isdirectory(path) == 1 then
+    vim.cmd("set rtp^=" .. path)
+  end
+end
+
+vim.cmd("runtime! plugin/plenary.vim")