#TIL 39 - How to fix "Not a test file" error with vim-test

What

Fix the vim-test "Not a test file" error when running tests from nested directories in a monorepo.

Why

vim-test looks for a project root marker (like package.json) starting from the current file's directory. In monorepos the nearest package.json may be several levels up — walking the path and setting g:test#project_root before running tells vim-test where Jest lives.

How

Create user command that finds project root by locating package.json:

local function setProjectRoot()
  local path = vim.fn.expand("%:p:h")
  for _ = 1, 5 do
    if vim.fn.filereadable(path .. "/package.json") == 1 then
      vim.g["test#project_root"] = path
      return
    end
    path = vim.fn.fnamemodify(path, ":h")
  end
end

vim.api.nvim_create_user_command("TestWithJest", function()
  setProjectRoot()
  vim.g["test#javascript#runner"] = "jest"
  vim.g["test#javascript#jest#executable"] = "npx jest"
  vim.cmd("TestNearest")
end, {})

Use :TestWithJest when in test files.