neovim/test/functional/preload.lua

-- Modules loaded here will NOT be cleared and reloaded by Busted.
-- Busted started doing this to help provide more isolation.  See issue #62
-- for more information about this.
local helpers = require('test.functional.helpers')(nil)
require('test.functional.ui.screen')
local busted = require("busted")
local is_os = helpers.is_os

if is_os('win') then
  local ffi = require('ffi')
  ffi.cdef[[
  typedef int errno_t;
  errno_t _set_fmode(int mode);
  ]]
  ffi.C._set_fmode(0x8000)
end

local testid = (function()
  local id = 0
  return (function()
    id = id + 1
    return id
  end)
end)()

-- Global before_each. https://github.com/Olivine-Labs/busted/issues/613
local function before_each(_element, _parent)
  local id = ('T%d'):format(testid())
  _G._nvim_test_id = id
  return nil, true
end
busted.subscribe({ 'test', 'start' },
  before_each,
  {
    -- Ensure our --helper is handled before --output (see busted/runner.lua).
    priority = 1,
    -- Don't generate a test-id for skipped tests. /shrug
    predicate = function (element, _, status)
      return not ((element.descriptor == 'pending' or status == 'pending'))
    end
  })