patch 9.1.0415: Some functions are not tested

Problem:  Some functions are not tested
Solution: Add a few more tests, fix a few minor problems
          (Yegappan Lakshmanan)

closes: #14789

Signed-off-by: Yegappan Lakshmanan <yegappan@yahoo.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_edit.vim b/src/testdir/test_edit.vim
index 789e44c..1665330 100644
--- a/src/testdir/test_edit.vim
+++ b/src/testdir/test_edit.vim
@@ -1952,6 +1952,11 @@
   let @r = 'sample'
   call feedkeys("a\<C-R>=SaveFirstLine()\<CR>", "xt")
   call assert_equal('"', g:Line)
+
+  " Test for inserting an null and an empty list
+  call feedkeys("a\<C-R>=test_null_list()\<CR>", "xt")
+  call feedkeys("a\<C-R>=[]\<CR>", "xt")
+  call assert_equal(['r'], getbufline('', 1, '$'))
   call test_override('ALL', 0)
   close!
 endfunc