diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index f7a438a..dbd0804 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -794,18 +794,41 @@
   set complete&
 endfunc
 
+" Test for append()
 func Test_append()
   enew!
   split
   call append(0, ["foo"])
+  call append(1, [])
+  call append(1, test_null_list())
+  call assert_equal(['foo', ''], getline(1, '$'))
   split
   only
   undo
+  undo
 
   " Using $ instead of '$' must give an error
   call assert_fails("call append($, 'foobar')", 'E116:')
 endfunc
 
+" Test for setline()
+func Test_setline()
+  new
+  call setline(0, ["foo"])
+  call setline(0, [])
+  call setline(0, test_null_list())
+  call setline(1, ["bar"])
+  call setline(1, [])
+  call setline(1, test_null_list())
+  call setline(2, [])
+  call setline(2, test_null_list())
+  call setline(3, [])
+  call setline(3, test_null_list())
+  call setline(2, ["baz"])
+  call assert_equal(['bar', 'baz'], getline(1, '$'))
+  close!
+endfunc
+
 func Test_getbufvar()
   let bnr = bufnr('%')
   let b:var_num = '1234'
@@ -913,6 +936,7 @@
   call assert_equal(-1, match(['a', 'b', 'c', 'a'], 'a', 5))
   call assert_equal(4,  match('testing', 'ing', -1))
   call assert_fails("let x=match('testing', 'ing', 0, [])", 'E745:')
+  call assert_equal(-1, match(test_null_list(), 2))
 endfunc
 
 func Test_matchend()
@@ -1796,6 +1820,7 @@
   call assert_equal(3, 'len'->call([123]))
   call assert_fails("call call('len', 123)", 'E714:')
   call assert_equal(0, call('', []))
+  call assert_equal(0, call('len', test_null_list()))
 
   function Mylen() dict
      return len(self.data)
@@ -1962,7 +1987,6 @@
   execute "normal! a\<C-r>=[complete(col('.'), range(10)), ''][1]\<CR>"
   " complete_info()
   execute "normal! a\<C-r>=[complete(col('.'), range(10)), ''][1]\<CR>\<C-r>=[complete_info(range(5)), ''][1]\<CR>"
-  call assert_fails('call complete(1, ["a"])', 'E785:')
 
   " copy()
   call assert_equal([1, 2, 3], copy(range(1, 3)))