Merge #9792

fixes #9791
closes #9792

runtime/doc/options.txt

@@ -5561,7 +5561,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 
 	After this option has been set successfully, Vim will source the files
 	"spell/LANG.vim" in 'runtimepath'.  "LANG" is the value of 'spelllang'
-	up to the first comma, dot or underscore.
+	up to the first character that is not an ASCII letter and not a dash.
 	Also see |set-spc-auto|.
 
 

src/nvim/testdir/test_modeline.vim

@@ -0,0 +1,84 @@
+func Test_modeline_invalid()
+   let modeline = &modeline
+   set modeline
+   call assert_fails('set Xmodeline', 'E518:')
+
+   let &modeline = modeline
+   bwipe!
+   call delete('Xmodeline')
+ endfunc
+
+func Test_modeline_filetype()
+  call writefile(['vim: set ft=c :', 'nothing'], 'Xmodeline_filetype')
+  let modeline = &modeline
+  set modeline
+  filetype plugin on
+  split Xmodeline_filetype
+  call assert_equal("c", &filetype)
+  call assert_equal(1, b:did_ftplugin)
+  call assert_equal("ccomplete#Complete", &ofu)
+
+  bwipe!
+  call delete('Xmodeline_filetype')
+  let &modeline = modeline
+  filetype plugin off
+endfunc
+
+func Test_modeline_syntax()
+  call writefile(['vim: set syn=c :', 'nothing'], 'Xmodeline_syntax')
+  let modeline = &modeline
+  set modeline
+  syntax enable
+  split Xmodeline_syntax
+  call assert_equal("c", &syntax)
+  call assert_equal("c", b:current_syntax)
+
+  bwipe!
+  call delete('Xmodeline_syntax')
+  let &modeline = modeline
+  syntax off
+endfunc
+
+func Test_modeline_keymap()
+  call writefile(['vim: set keymap=greek :', 'nothing'], 'Xmodeline_keymap')
+  let modeline = &modeline
+  set modeline
+  split Xmodeline_keymap
+  call assert_equal("greek", &keymap)
+  call assert_match('greek\|grk', b:keymap_name)
+
+  bwipe!
+  call delete('Xmodeline_keymap')
+  let &modeline = modeline
+  set keymap= iminsert=0 imsearch=-1
+endfunc
+
+func s:modeline_fails(what, text)
+  let fname = "Xmodeline_fails_" . a:what
+  call writefile(['vim: set ' . a:text . ' :', 'nothing'], fname)
+  let modeline = &modeline
+  set modeline
+  filetype plugin on
+  syntax enable
+  call assert_fails('split ' . fname, 'E474:')
+  call assert_equal("", &filetype)
+  call assert_equal("", &syntax)
+
+  bwipe!
+  call delete(fname)
+  let &modeline = modeline
+  filetype plugin off
+  syntax off
+endfunc
+
+func Test_modeline_filetype_fails()
+  call s:modeline_fails('filetype', 'ft=evil$CMD')
+endfunc
+
+func Test_modeline_syntax_fails()
+  call s:modeline_fails('syntax', 'syn=evil$CMD')
+endfunc
+
+func Test_modeline_keymap_fails()
+  call s:modeline_fails('keymap', 'keymap=evil$CMD')
+endfunc