patch 8.1.0832: confirm() is not tested

Problem:    confirm() is not tested.
Solution:   Add a test. (Dominique Pelle, closes #3868)

src/testdir/test_functions.vim

@@ -1153,3 +1153,58 @@ func Test_func_exists_on_reload()
   call delete('Xfuncexists')
   delfunc ExistingFunction
 endfunc
+
+" Test confirm({msg} [, {choices} [, {default} [, {type}]]])
+func Test_confirm()
+  if !has('unix') || has('gui_running')
+    return
+  endif
+
+  call feedkeys('o', 'L')
+  let a = confirm('Press O to proceed')
+  call assert_equal(1, a)
+
+  call feedkeys('y', 'L')
+  let a = confirm('Are you sure?', "&Yes\n&No")
+  call assert_equal(1, a)
+
+  call feedkeys('n', 'L')
+  let a = confirm('Are you sure?', "&Yes\n&No")
+  call assert_equal(2, a)
+
+  " confirm() should return 0 when pressing CTRL-C.
+  call feedkeys("\<C-c>", 'L')
+  let a = confirm('Are you sure?', "&Yes\n&No")
+  call assert_equal(0, a)
+
+  " <Esc> requires another character to avoid it being seen as the start of an
+  " escape sequence.  Zero should be harmless.
+  call feedkeys("\<Esc>0", 'L')
+  let a = confirm('Are you sure?', "&Yes\n&No")
+  call assert_equal(0, a)
+
+  " Default choice is returned when pressing <CR>.
+  call feedkeys("\<CR>", 'L')
+  let a = confirm('Are you sure?', "&Yes\n&No")
+  call assert_equal(1, a)
+
+  call feedkeys("\<CR>", 'L')
+  let a = confirm('Are you sure?', "&Yes\n&No", 2)
+  call assert_equal(2, a)
+
+  call feedkeys("\<CR>", 'L')
+  let a = confirm('Are you sure?', "&Yes\n&No", 0)
+  call assert_equal(0, a)
+
+  " Test with the {type} 4th argument
+  for type in ['Error', 'Question', 'Info', 'Warning', 'Generic']
+    call feedkeys('y', 'L')
+    let a = confirm('Are you sure?', "&Yes\n&No\n", 1, type)
+    call assert_equal(1, a)
+  endfor
+
+  call assert_fails('call confirm([])', 'E730:')
+  call assert_fails('call confirm("Are you sure?", [])', 'E730:')
+  call assert_fails('call confirm("Are you sure?", "&Yes\n&No\n", [])', 'E745:')
+  call assert_fails('call confirm("Are you sure?", "&Yes\n&No\n", 0, [])', 'E730:')
+endfunc

src/version.c

@@ -783,6 +783,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    832,
 /**/
     831,
 /**/