patch 8.2.0270: some code not covered by tests

Problem:    Some code not covered by tests.
Solution:   Add test cases. (Yegappan Lakshmanan, closes #5649)
diff --git a/src/testdir/test_vimscript.vim b/src/testdir/test_vimscript.vim
index a422a6d..a75e5f6 100644
--- a/src/testdir/test_vimscript.vim
+++ b/src/testdir/test_vimscript.vim
@@ -2061,6 +2061,16 @@
   call delete('Xscript')
 endfunc
 
+" Test for <sfile>, <slnum> in a function                           {{{1
+func Test_sfile_in_function()
+  func Xfunc()
+    call assert_match('..Test_sfile_in_function\[5]..Xfunc', expand('<sfile>'))
+    call assert_equal('2', expand('<slnum>'))
+  endfunc
+  call Xfunc()
+  delfunc Xfunc
+endfunc
+
 "-------------------------------------------------------------------------------
 " Modelines								    {{{1
 " vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker