vim-patch:9.1.0721: tests: test_mksession does not consider XDG_CONFIG_HOME

Problem:  tests: test_mksession does not consider XDG_CONFIG_HOME
Solution: allow to match $HOME/.vim/ and $HOME/.config/vim for &viewdir
          (John M Devin)

closes: vim/vim#15639

5b9237c2e7

Co-authored-by: John M Devin <john.m.devin@gmail.com>
(cherry picked from commit 0eb708aa8a)

test/old/testdir/setup.vim

@@ -113,6 +113,10 @@ endif
 " defaults before we get here, and test_mksession checks that.
 let $ORIGHOME = $HOME
 
+if !exists('$XDG_CONFIG_HOME')
+  let $XDG_CONFIG_HOME = $HOME .. '/.config'
+endif
+
 " Make sure $HOME does not get read or written.
 let $HOME = expand(getcwd() . '/XfakeHOME')
 if !isdirectory($HOME)

test/old/testdir/test_mksession.vim

@@ -1205,7 +1205,10 @@ func Test_mkview_default_home()
     " use escape() to handle backslash path separators
     call assert_match('^' .. escape($ORIGHOME, '\') .. '/vimfiles', &viewdir)
   elseif has('unix')
-    call assert_match('^' .. $ORIGHOME .. '/.vim', &viewdir)
+    call assert_match(
+          \ '^' .. $ORIGHOME .. '/.vim\|' ..
+          \ '^' .. $XDG_CONFIG_HOME .. '/vim'
+          \ , &viewdir)
   elseif has('amiga')
     call assert_match('^home:vimfiles', &viewdir)
   elseif has('mac')