Getting underline attribute from syntax hl group returns empty string instead of '1'

[kristijanhusak]

Neovim version (nvim -v)

NVIM v0.7.0-dev+1194-g24d56116f

Vim (not Nvim) behaves the same?

no, vim 8.2.4464

Operating system/version

Linux

Terminal name/version

Kitty

$TERM environment variable

xterm-kitty

Installation

Built from source

How to reproduce the issue

nvim --clean
:hi UnderlineTest gui=underline
:echo synIDattr(synIDtrans(hlID('UnderlineTest')), 'underline')

Expected behavior

Expected to get 1 returned.

This also properly works in stable versions of Neovim since 0.5.0.

Figured this issue from the tests in nvim-orgmode: https://github.com/nvim-orgmode/orgmode/runs/5439299419?check_suite_focus=true#step:7:96

Link to line where the test fails: https://github.com/nvim-orgmode/orgmode/blob/master/tests/plenary/colors/colors_spec.lua#L79

Actual behavior

Getting the empty string.

[jamessan]

Fallout from @kchibisov's PR. We should be testing the properties individually, so this type of thing gets caught.

[kchibisov]

@jamessan I'd assume the tests should go into functional/terminal/highlight_spec.lua?

[jamessan]

That or functional/ex_cmds/highlight_spec.lua would work.