neovim/test/functional/vimscript/exepath_spec.lua

local helpers = require('test.functional.helpers')(after_each)
local eq, clear, call =
  helpers.eq, helpers.clear, helpers.call
local command = helpers.command
local exc_exec = helpers.exc_exec
local matches = helpers.matches
local is_os = helpers.is_os
local set_shell_powershell = helpers.set_shell_powershell
local eval = helpers.eval

local find_dummies = function(ext_pat)
  local tmp_path = eval('$PATH')
  command('let $PATH = fnamemodify("./test/functional/fixtures/bin", ":p")')
  matches('null' .. ext_pat, call('exepath', 'null'))
  matches('true' .. ext_pat, call('exepath', 'true'))
  matches('false' .. ext_pat, call('exepath', 'false'))
  command("let $PATH = '"..tmp_path.."'")
end

describe('exepath()', function()
  before_each(clear)

  it('fails for invalid values', function()
    for _, input in ipairs({'v:null', 'v:true', 'v:false', '{}', '[]'}) do
      eq('Vim(call):E1174: String required for argument 1', exc_exec('call exepath('..input..')'))
    end
    eq('Vim(call):E1175: Non-empty string required for argument 1', exc_exec('call exepath("")'))
    command('let $PATH = fnamemodify("./test/functional/fixtures/bin", ":p")')
    for _, input in ipairs({'v:null', 'v:true', 'v:false'}) do
      eq('Vim(call):E1174: String required for argument 1', exc_exec('call exepath('..input..')'))
    end
  end)

  if is_os('win') then
    it('returns 1 for commands in $PATH (Windows)', function()
      local exe = 'ping'
      matches(exe .. '%.EXE$', call('exepath', exe))
    end)

    it('append extension if omitted', function()
      local filename = 'cmd'
      local pathext = '.exe'
      clear({env={PATHEXT=pathext}})
      eq(call('exepath', filename..pathext), call('exepath', filename))
    end)

    it('returns file WITH extension if files both with and without extension exist in $PATH', function()
      local ext_pat = '%.CMD$'
      find_dummies(ext_pat)
      set_shell_powershell()
      find_dummies(ext_pat)
    end)
  else
    it('returns 1 for commands in $PATH (not Windows)', function()
      local exe = 'ls'
      matches(exe .. '$', call('exepath', exe))
    end)

    it('returns file WITHOUT extension if files both with and without extension exist in $PATH', function()
      find_dummies('$')
    end)
  end
end)