patch 8.2.1432: various inconsistencies in test files

Problem:    Various inconsistencies in test files.
Solution:   Add modelines where they were missing.  Use Check commands instead
            of silently skipping over tests.  Adjust indents and comments.
            (Ken Takata, closes #6695)
diff --git a/src/testdir/test_cd.vim b/src/testdir/test_cd.vim
index 8a0fbb2..0899bcd 100644
--- a/src/testdir/test_cd.vim
+++ b/src/testdir/test_cd.vim
@@ -191,3 +191,5 @@
   call delete('XComplDir2', 'd')
   call delete('XComplFile')
 endfunc
+
+" vim: shiftwidth=2 sts=2 expandtab