patch 8.2.1022: various parts of code not covered by tests

Problem:    Various parts of code not covered by tests.
Solution:   Add more tests. (Yegappan Lakshmanan, closes #6300)
diff --git a/src/testdir/test_digraph.vim b/src/testdir/test_digraph.vim
index 2a59994..f73ed7c 100644
--- a/src/testdir/test_digraph.vim
+++ b/src/testdir/test_digraph.vim
@@ -2,6 +2,7 @@
 
 source check.vim
 CheckFeature digraphs
+source term_util.vim
 
 func Put_Dig(chars)
   exe "norm! o\<c-k>".a:chars
@@ -502,4 +503,20 @@
   call delete('Xkeymap')
 endfunc
 
+" Test for the characters displayed one the screen when entering a digraph
+func Test_entering_digraph()
+  CheckRunVimInTerminal
+  let buf = RunVimInTerminal('', {'rows': 6})
+  call term_sendkeys(buf, "i\<C-K>")
+  call term_wait(buf)
+  call assert_equal('?', term_getline(buf, 1))
+  call term_sendkeys(buf, "1")
+  call term_wait(buf)
+  call assert_equal('1', term_getline(buf, 1))
+  call term_sendkeys(buf, "2")
+  call term_wait(buf)
+  call assert_equal('½', term_getline(buf, 1))
+  call StopVimInTerminal(buf)
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab