test: use spawn_wait() instead of system() #31852

Problem:
Tests that need to check `nvim` CLI behavior (no RPC session) create
their own ad-hoc `system()` wrappers.

Solution:
- Use `n.spawn_wait` instead of `system()`.
- Bonus: this also improves the tests by explicitly checking for
  `stdout` or `stderr`. And if a signal is raised, `ProcStream.status`
  will reflect it.

1 files changed, 38 insertions, 62 deletions

diff --git a/test/functional/core/main_spec.lua b/test/functional/core/main_spec.lua
index ce4ba1905f..6add49ceae 100644
--- a/test/functional/core/main_spec.lua
+++ b/test/functional/core/main_spec.lua
@@ -9,7 +9,6 @@ local feed = n.feed
 local eval = n.eval
 local clear = n.clear
 local fn = n.fn
-local nvim_prog_abs = n.nvim_prog_abs
 local write_file = t.write_file
 local is_os = t.is_os
 local skip = t.skip
@@ -35,7 +34,7 @@ describe('command-line option', function()
     it('treats - as stdin', function()
       eq(nil, uv.fs_stat(fname))
       fn.system({
-        nvim_prog_abs(),
+        n.nvim_prog,
         '-u',
         'NONE',
         '-i',
@@ -56,41 +55,29 @@ describe('command-line option', function()
       eq(nil, uv.fs_stat(fname))
       eq(true, not not dollar_fname:find('%$%w+'))
       write_file(dollar_fname, ':call setline(1, "100500")\n:wqall!\n')
-      fn.system({
-        nvim_prog_abs(),
-        '-u',
-        'NONE',
-        '-i',
-        'NONE',
-        '--headless',
+      local p = n.spawn_wait(
         '--cmd',
         'set noswapfile shortmess+=IFW fileformats=unix',
         '-s',
         dollar_fname,
-        fname,
-      })
-      eq(0, eval('v:shell_error'))
+        fname
+      )
+      eq(0, p.status)
       local attrs = uv.fs_stat(fname)
       eq(#'100500\n', attrs.size)
     end)
 
-    it('does not crash when run completion in ex mode', function()
-      fn.system({
-        nvim_prog_abs(),
-        '--clean',
-        '-e',
-        '-s',
-        '--cmd',
-        'exe "norm! i\\<C-X>\\<C-V>"',
-      })
-      eq(0, eval('v:shell_error'))
+    it('does not crash when run completion in Ex mode', function()
+      local p =
+        n.spawn_wait('--clean', '-e', '-s', '--cmd', 'exe "norm! i\\<C-X>\\<C-V>"', '--cmd', 'qa!')
+      eq(0, p.status)
     end)
 
     it('does not crash after reading from stdin in non-headless mode', function()
       skip(is_os('win'))
       local screen = Screen.new(40, 8)
       local args = {
-        nvim_prog_abs(),
+        n.nvim_prog,
         '-u',
         'NONE',
         '-i',
@@ -138,51 +125,40 @@ describe('command-line option', function()
       ]=]
     end)
 
-    it('errors out when trying to use nonexistent file with -s', function()
+    it('fails when trying to use nonexistent file with -s', function()
+      local p = n.spawn_wait(
+        '--cmd',
+        'set noswapfile shortmess+=IFW fileformats=unix',
+        '--cmd',
+        'language C',
+        '-s',
+        nonexistent_fname
+      )
       eq(
         'Cannot open for reading: "' .. nonexistent_fname .. '": no such file or directory\n',
-        fn.system({
-          nvim_prog_abs(),
-          '-u',
-          'NONE',
-          '-i',
-          'NONE',
-          '--headless',
-          '--cmd',
-          'set noswapfile shortmess+=IFW fileformats=unix',
-          '--cmd',
-          'language C',
-          '-s',
-          nonexistent_fname,
-        })
+        --- TODO(justinmk): using `p.output` because Nvim emits CRLF even on non-Win. Emit LF instead?
+        p:output()
       )
-      eq(2, eval('v:shell_error'))
+      eq(2, p.status)
     end)
 
     it('errors out when trying to use -s twice', function()
       write_file(fname, ':call setline(1, "1")\n:wqall!\n')
       write_file(dollar_fname, ':call setline(1, "2")\n:wqall!\n')
-      eq(
-        'Attempt to open script file again: "-s ' .. dollar_fname .. '"\n',
-        fn.system({
-          nvim_prog_abs(),
-          '-u',
-          'NONE',
-          '-i',
-          'NONE',
-          '--headless',
-          '--cmd',
-          'set noswapfile shortmess+=IFW fileformats=unix',
-          '--cmd',
-          'language C',
-          '-s',
-          fname,
-          '-s',
-          dollar_fname,
-          fname_2,
-        })
+      local p = n.spawn_wait(
+        '--cmd',
+        'set noswapfile shortmess+=IFW fileformats=unix',
+        '--cmd',
+        'language C',
+        '-s',
+        fname,
+        '-s',
+        dollar_fname,
+        fname_2
       )
-      eq(2, eval('v:shell_error'))
+      --- TODO(justinmk): using `p.output` because Nvim emits CRLF even on non-Win. Emit LF instead?
+      eq('Attempt to open script file again: "-s ' .. dollar_fname .. '"\n', p:output())
+      eq(2, p.status)
       eq(nil, uv.fs_stat(fname_2))
     end)
   end)
@@ -190,8 +166,8 @@ describe('command-line option', function()
   it('nvim -v, :version', function()
     matches('Run ":verbose version"', fn.execute(':version'))
     matches('fall%-back for %$VIM: .*Run :checkhealth', fn.execute(':verbose version'))
-    matches('Run "nvim %-V1 %-v"', fn.system({ nvim_prog_abs(), '-v' }))
-    matches('fall%-back for %$VIM: .*Run :checkhealth', fn.system({ nvim_prog_abs(), '-V1', '-v' }))
+    matches('Run "nvim %-V1 %-v"', n.spawn_wait('-v').stdout)
+    matches('fall%-back for %$VIM: .*Run :checkhealth', n.spawn_wait('-V1', '-v').stdout)
   end)
 
   if is_os('win') then
@@ -205,7 +181,7 @@ describe('command-line option', function()
         eq(
           'some text',
           fn.system({
-            nvim_prog_abs(),
+            n.nvim_prog,
             '-es',
             '+%print',
             '+q',