feat(lua)!: execute Lua with "nvim -l"

[justinmk]

Examples

nvim  bar.txt -l foo.lua
echo 'print(vim.inspect(vim.api.nvim_buf_get_text(1,0,0,-1,-1,{})))' | nvim +"put ='text'" -l -
echo "print(vim.inspect(_G.arg))" | nvim -l - --arg1 --arg2

closes #15749

Todo

• tests for shada/swap/userconfig
• exit 1 on lua error
• exit without +q
• update docs-gen CI job
• support -l - (stdin)
• need some sort of vim.is_main() magic function that detects whether the current module is the thing executed by nvim -l.
  • somewhat mitigated by _G.arg[0] lua: "nvim -l" scriptname in _G.arg[0], eliminate bump-deps.sh #21663
• adjust places that test verbose==1
• ensure final \n in output?
• fix: os_msg, os_errmsg should not truncate based on screen width!

Future

To run tests with nvim instead of lua or luajit, change .deps/usr/bin/busted script as follows:

#!/bin/sh

LUAROCKS_SYSCONFDIR='/…/.deps/usr/etc/luarocks' exec '/…/build/bin/nvim' -c 'lua package.path="/…/.deps/usr/share/lua/5.1/?.lua;/…/.deps/usr/share/lua/5.1/?/init.lua;"..package.path;package.cpath="/…/.deps/usr/lib/lua/5.1/?.so;"..package.cpath;local k,l,_=pcall(require,"luarocks.loader") _=k and l.add_context("busted","2.0.0-1")' -l '/…/.deps/usr/lib/luarocks/rocks-5.1/busted/2.0.0-1/bin/busted' "$@"

With this PR, plus this patch:

diff --git a/test/functional/helpers.lua b/test/functional/helpers.lua
index ca59eb31828b..a01d62af98e9 100644
--- a/test/functional/helpers.lua
+++ b/test/functional/helpers.lua
@@ -957,7 +957,7 @@ function module.mkdir_p(path)
     or 'mkdir -p '..path))
 end
 
-module = global_helpers.tbl_extend('error', module, global_helpers)
+module = global_helpers.tbl_extend('keep', module, global_helpers)
 
 return function(after_each)
   if after_each then
diff --git a/test/helpers.lua b/test/helpers.lua
index 3fe4322501a3..320b826b6da5 100644
--- a/test/helpers.lua
+++ b/test/helpers.lua
@@ -811,6 +811,6 @@ function module.read_nvim_log(logfile, ci_rename)
   return log
 end
 
-module = shared.tbl_extend('error', module, Paths, shared, require('test.deprecated'))
+module = shared.tbl_extend('keep', module, Paths, shared, require('test.deprecated'))
 
 return module

tests run successfully using nvim as the test runner:

|| -------- Running tests from test/functional/core/startup_spec.lua
|| RUN      T1 startup -l Lua failure modes: 23.30 ms OK
|| RUN      T2 startup -l Lua os.exit() sets Nvim exitcode: 39.30 ms OK
|| RUN      T3 startup -l Lua sets _G.arg: 189.28 ms OK
|| -------- 3 tests from test/functional/core/startup_spec.lua (262.84 ms total)
|| 
|| -------- Global test environment teardown.
|| ======== 3 tests from 1 test file ran. (263.25 ms total)
|| PASSED   3 tests.

and fail correctly:

|| ERROR    test/functional/core/startup_spec.lua @ 99: startup -l Lua failure modes
|| test/helpers.lua:85: Pattern does not match.
|| Pattern:
|| nvim: XArgument missing after: "%-l"
|| Actual:
|| nvim: Argument missing after: "-l"
|| More info with "nvim -h"

[justinmk]

test failing on windows... is there a problem with getting output from system(['nvim', '-es', ...]) there?

[zeertzjq]

Maybe some Vim patches are missing for os_msg() and os_errmsg() on Windows?

• vim/vim@9b5c1fc
• vim/vim@97c2c05
• vim/vim@a97c363

[justinmk]

Maybe some Vim patches are missing for os_msg() and os_errmsg() on Windows?

thank you for the help! actually Nvim was crashing (bug in nlua_set_argv) in the nested system() call, which returned empty output. probably can make this better by checking v:shell_error in assert_l_out before checking the output.

[justinmk]

after merging this,

• regen-api-docs job will fail until nightly has this feature
• we can use nvim as the test-runner instead of lua
  • eliminates most of the test util functions in helpers.lua.
  • see the "Future" note above.

[justinmk]

Leaving this here and documented in CONTRIBUTING.md to help others.

[dundargoc]

Just put one set of environment variables at the top level instead?

[justinmk]

That didn't seem to work when I tried it...

[justinmk]

ci failure looks unrelated:

FAILED   test/functional/terminal/tui_spec.lua @ 2372: TUI as a client throws error when no server exists
test/functional/terminal/tui_spec.lua:2380: Row 2 did not match.
Expected:
  |Remote ui failed to start: {MATCH:.*}|
  |*                                                            |
  |*[Process exited 1]{1: }                                         |
  |*                                                            |
  |                                                            |
  |                                                            |
  |{3:-- TERMINAL --}                                              |
Actual:
  |Remote ui failed to start: failed to lookup host o          |
  |*r port                                                      |
  |*                                                            |
  |*[Process exited 1]{1: }                                         |
  |                                                            |
  |                                                            |
  |{3:-- TERMINAL --}                                              |