legacy tests: migrate test103

src/nvim/testdir/test103.in

@@ -1,37 +0,0 @@
-Test for visual mode not being reset causing E315 error.
-STARTTEST
-:so small.vim
-:enew
-:let g:msg="Everything's fine."
-:function! TriggerTheProblem()
-:	" At this point there is no visual selection because :call reset it.
-:	" Let's restore the selection:
-:	normal gv
-:	'<,'>del _
-:	try
-:		exe "normal \<Esc>"
-:	catch /^Vim\%((\a\+)\)\=:E315/
-:		echom 'Snap! E315 error!'
-:		let g:msg='Snap! E315 error!'
-:	endtry
-:endfunction
-:enew
-:setl buftype=nofile
-:call append(line('$'), 'Delete this line.')
-:"
-:"
-:" NOTE: this has to be done by a call to a function because executing :del the
-:"       ex-way will require the colon operator which resets the visual mode thus
-:"       preventing the problem:
-:"
-GV:call TriggerTheProblem()
-:%del _
-:call append(line('$'), g:msg)
-:w! test.out
-:brewind
-ENDTEST
-
-STARTTEST
-:qa!
-ENDTEST
-

src/nvim/testdir/test103.ok

@@ -1,2 +0,0 @@
-
-Everything's fine.

test/functional/legacy/103_visual_mode_reset.lua

@@ -0,0 +1,47 @@
+-- Test for visual mode not being reset causing E315 error.
+
+local helpers = require('test.functional.helpers')
+local feed, insert, source = helpers.feed, helpers.insert, helpers.source
+local clear, execute, expect = helpers.clear, helpers.execute, helpers.expect
+
+describe('E315 error', function()
+  setup(clear)
+
+  it('is working', function()
+    -- At this point there is no visual selection because :call reset it.
+    -- Let's restore the selection:
+    source([[
+      let g:msg="Everything's fine."
+      function! TriggerTheProblem()
+          normal gv
+          '<,'>del _
+          try
+              exe "normal \<Esc>"
+          catch /^Vim\%((\a\+)\)\=:E315/
+              echom 'Snap! E315 error!'
+              let g:msg='Snap! E315 error!'
+          endtry
+      endfunction
+      enew
+      enew
+      setl buftype=nofile
+      call append(line('$'), 'Delete this line.')
+    ]])
+
+    -- NOTE: this has to be done by a call to a function because executing
+    -- :del the ex-way will require the colon operator which resets the
+    -- visual mode thus preventing the problem:
+    feed('GV:call TriggerTheProblem()<cr>')
+  
+    source([[
+      %del _
+      call append(line('$'), g:msg)
+      brewind
+    ]])
+
+    -- Assert buffer contents.
+    expect([[
+      
+      Everything's fine.]])
+  end)
+end)