patch 8.0.1816: no test for setcmdpos()

Problem:    No test for setcmdpos().
Solution:   Add a test. (Dominique Pelle, closes #2901)

src/testdir/test_cmdline.vim

@@ -470,4 +470,25 @@ func Test_verbosefile()
  call delete('Xlog')
endfunc

func Test_setcmdpos()
  func InsertTextAtPos(text, pos)
    call assert_equal(0, setcmdpos(a:pos))
    return a:text
  endfunc

  " setcmdpos() with position in the middle of the command line.
  call feedkeys(":\"12\<C-R>=InsertTextAtPos('a', 3)\<CR>b\<CR>", 'xt')
  call assert_equal('"1ab2', @:)

  call feedkeys(":\"12\<C-R>\<C-R>=InsertTextAtPos('a', 3)\<CR>b\<CR>", 'xt')
  call assert_equal('"1b2a', @:)

  " setcmdpos() with position beyond the end of the command line.
  call feedkeys(":\"12\<C-B>\<C-R>=InsertTextAtPos('a', 10)\<CR>b\<CR>", 'xt')
  call assert_equal('"12ab', @:)

  " setcmdpos() returns 1 when not editing the command line.
  call assert_equal(1, setcmdpos(3))
endfunc

set cpo&

src/version.c

@@ -761,6 +761,8 @@ static char *(features[]) =

static int included_patches[] =
{   /* Add new patch number below this line */
/**/
    1816,
/**/
    1815,
/**/