neovim/test/functional/lua/ffi_spec.lua

local helpers = require('test.functional.helpers')(after_each)
local eq = helpers.eq
local exec_lua = helpers.exec_lua
local clear = helpers.clear

before_each(clear)

describe('ffi.cdef', function()
  it('can use Neovim core functions', function()
    if not exec_lua("return pcall(require, 'ffi')") then
      pending('missing LuaJIT FFI')
    end

    eq(12, exec_lua[[
      local ffi = require('ffi')

      ffi.cdef('int curwin_col_off(void);')

      vim.cmd('set number numberwidth=4 signcolumn=yes:4')

      return ffi.C.curwin_col_off()
    ]])

    eq(20, exec_lua[=[
      local ffi = require('ffi')

      ffi.cdef[[
        typedef unsigned char char_u;
        typedef struct window_S win_T;
        typedef struct {} stl_hlrec_t;
        typedef struct {} StlClickRecord;
        typedef struct {} Error;

        win_T *find_window_by_handle(int Window, Error *err);

        int build_stl_str_hl(
          win_T *wp,
          char_u *out,
          size_t outlen,
          char_u *fmt,
          int use_sandbox,
          char_u fillchar,
          int maxwidth,
          stl_hlrec_t **hltab,
          StlClickRecord **tabtab
        );
      ]]

      return ffi.C.build_stl_str_hl(
        ffi.C.find_window_by_handle(0, ffi.new('Error')),
        ffi.new('char_u[1024]'),
        1024,
        ffi.cast('char_u*', 'StatusLineOfLength20'),
        0,
        0,
        0,
        nil,
        nil
      )
    ]=])
  end)
end)