Test "cancels stale events on channel close" hangs on macOS when coreutils is installed via brew (or nix)

[mjlbach]

• nvim --version: nightly (commit e85c8df)
• vim -u DEFAULTS (version: ) behaves differently? No
• Operating system/version: macOS
• Terminal name/version: iterm
• $TERM: xterm-256color

Steps to reproduce using nvim -u NORC

brew install coreutils  # or nix-env -iA nixpkgs.coreutils
PATH="/usr/local/opt/coreutils/libexec/gnubin:$PATH"
TEST_FILE="test/functional/api/server_notifications_spec.lua" make test

Actual behaviour

Test hangs

Expected behaviour

Test doesn't hang

[bfredl]

your cat is too fast.

Seems like a hidden timing issue (ideally the test should not depend on timing at all)

[mjlbach]

I'm not sure I really understand this test

  it('cancels stale events on channel close', function()
    if helpers.pending_win32(pending) then return end
    local catchan = eval("jobstart(['cat'], {'rpc': v:true})")
    eq({id=catchan, stream='job', mode='rpc', client = {}}, exec_lua ([[
      vim.rpcnotify(..., "nvim_call_function", 'chanclose', {..., 'rpc'})
      vim.rpcnotify(..., "nvim_subscribe", "daily_rant")
      return vim.api.nvim_get_chan_info(...)
    ]], catchan))
    eq(2, eval('1+1'))  -- Still alive?
    eq({false, 'Invalid channel: '..catchan},
      exec_lua ([[ return {pcall(vim.rpcrequest, ..., 'nvim_eval', '1+1')}]], catchan))
    retry(nil, 3000, function() eq({}, meths.get_chan_info(catchan)) end) -- cat be dead :(
  end)

Seems like it's trying to send a message to a closed channel. If I run the following excerpt via luafile, it also hangs (including on linux).

local catchan = vim.fn.jobstart({'cat'}, {rpc = true})
vim.rpcnotify(catchan, "nvim_call_function", 'chanclose', {catchan, 'rpc'})
vim.rpcnotify(catchan, "nvim_subscribe", "daily_rant")
print(vim.inspect(vim.api.nvim_get_chan_info(catchan)))
print(1+1)
pcall(vim.rpcrequest, catchan, 'nvim_eval', '1+1')