patch 8.0.0485: not all windows commands are tested

Problem:    Not all windows commands are tested.
Solution:   Add more tests for windows commands. (Dominique Pelle,
            closes #1575) Run test_autocmd separately, it interferes with
            other tests.  Fix tests that depended on side effects.
diff --git a/src/testdir/test_delete.vim b/src/testdir/test_delete.vim
index 3cf2623..4686a0d 100644
--- a/src/testdir/test_delete.vim
+++ b/src/testdir/test_delete.vim
@@ -8,6 +8,7 @@
   call assert_equal(0, delete('Xfile'))
   call assert_fails('call readfile("Xfile")', 'E484:')
   call assert_equal(-1, delete('Xfile'))
+  bwipe Xfile
 endfunc
 
 func Test_dir_delete()
@@ -35,6 +36,8 @@
   call assert_equal(0, delete('Xdir1', 'rf'))
   call assert_false(isdirectory('Xdir1'))
   call assert_equal(-1, delete('Xdir1', 'd'))
+  bwipe Xdir1/Xfile
+  bwipe Xdir1/subdir/Xfile
 endfunc
 
 func Test_symlink_delete()
@@ -49,6 +52,7 @@
   call assert_equal(0, delete('Xlink'))
   call assert_equal(-1, delete('Xlink'))
   call assert_equal(0, delete('Xfile'))
+  bwipe Xfile
 endfunc
 
 func Test_symlink_dir_delete()
@@ -96,4 +100,8 @@
   call assert_equal(['a', 'b'], readfile('Xdir4/Xfile'))
   call assert_equal(0, delete('Xdir4/Xfile'))
   call assert_equal(0, delete('Xdir4', 'd'))
+
+  bwipe Xdir3/Xfile
+  bwipe Xdir3/subdir/Xfile
+  bwipe Xdir4/Xfile
 endfunc