patch 8.2.2608: character input not fully tested

Problem:    Character input not fully tested.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #7963)
diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 64afe54..ca57c30 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -1430,6 +1430,14 @@
   delfunc Tcomplete
   call assert_equal('item1 item2 item3', c)
 
+  " Test for using special characters as default input
+  call feedkeys(":let c = input('name? ', \"x\<BS>y\")\<CR>\<CR>", 'xt')
+  call assert_equal('y', c)
+
+  " Test for using <CR> as default input
+  call feedkeys(":let c = input('name? ', \"\\<CR>\")\<CR>x\<CR>", 'xt')
+  call assert_equal(' x', c)
+
   call assert_fails("call input('F:', '', 'invalid')", 'E180:')
   call assert_fails("call input('F:', '', [])", 'E730:')
 endfunc