eval: executable(), exepath() accept strings only

Cherry-pick f_executable(), f_exepath(), check_for_string() from patch 8.2.2117.
Rename check_for_string() to tv_check_for_string().
https://github.com/vim/vim/commit/7bb4e74c38642682cfdd0cb4052adfa5efdd7dd1

Close https://github.com/neovim/neovim/issues/13485

1 files changed, 11 insertions, 0 deletions

diff --git a/test/functional/eval/executable_spec.lua b/test/functional/eval/executable_spec.lua
index a1cf056907..f8e579a8ff 100644
--- a/test/functional/eval/executable_spec.lua
+++ b/test/functional/eval/executable_spec.lua
@@ -2,6 +2,7 @@ local helpers = require('test.functional.helpers')(after_each)
 local eq, clear, call, iswin, write_file, command =
   helpers.eq, helpers.clear, helpers.call, helpers.iswin, helpers.write_file,
   helpers.command
+local exc_exec = helpers.exc_exec
 local eval = helpers.eval
 
 describe('executable()', function()
@@ -12,6 +13,16 @@ describe('executable()', function()
     eq(1, call('executable', exe))
   end)
 
+  it('fails for invalid values', function()
+    for _, input in ipairs({'""', 'v:null', 'v:true', 'v:false', '{}', '[]'}) do
+      eq('Vim(call):E928: String required', exc_exec('call executable('..input..')'))
+    end
+    command('let $PATH = fnamemodify("./test/functional/fixtures/bin", ":p")')
+    for _, input in ipairs({'v:null', 'v:true', 'v:false'}) do
+      eq('Vim(call):E928: String required', exc_exec('call executable('..input..')'))
+    end
+  end)
+
   it('returns 0 for non-existent files', function()
     eq(0, call('executable', 'no_such_file_exists_209ufq23f'))
   end)